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NetLogo 3.1.4 User Manual

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1. 188 How does NetLogo decide when to switch from agent to agent when running code 188 How GO stop foreach id da coo dai ad na va ada di a 189 How do make an empty ageniset e eeeeeerarereeeaeanaaeaaaeereaaaaana 189 Primitives Diction A y a aae e aea a seio a aape aa r aeaa aaeeea aaea aena odio nda riada rasta astro 191 Categories A O AY 191 TUE la NS 191 Patch related priMitiVeS coccccccconnconncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnenenineness 191 Agentsel primitive Ss e e id a dar ca 191 ASOLO RIEL OS a SAS A ci E SR Rad 192 Control flow and logic primitivos 0 aid 192 W Onl primitives it A A Ai 192 Perspective priMitiVeS cocccoccccccconcccnnnnncnnnnnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninenoss 192 HubNet priMitiVeS ooocccccccoccconcconcnoncnoncnoncnnnnnnnnnnnnnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnineninnnnss 192 Input output pPriMitiVES ccocccccncnnncnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnineninnnnss 192 Flep S cai Ac 192 List PRIMITIVOS aliada aaa 192 SINO PARIS St a n e iaa 193 Mathematical priMitiVeS oooooocononnnonnnoccoconoonnnonnonnnonnnnnnnnnnnnnnnn nono nnnnnnnnnnnnnnnnnnnnnnnnnnnnonnnnnnos 193 PILOTING DIMINUTIVE cc tia a 193 LINK PIIMIIVES eeen ae e EI aio Ra RxE a saeantendetueaseatecesueasnsaiaa eS ida Rana 193 Wee ce 193 System PriMIVOS has carstscoaeteectaadadeteanstatvals o 193 Built
2. We are using the if command for the first time Look at the code carefully Each turtle when it runs these commands compares the value of the patch color it is on pcolor to the value for green A turtle has direct access to the variables of the patch it is standing on If the patch color is green the comparison reports t rue and only then will the turtle runs the commands inside the brackets otherwise it skips them The commands make the turtle change the patch color to black and increase its own energy by 10 The patch turns black to signify that the grass at that spot has been eaten and the turtle is given more energy from having just eaten the grass Next let s make the movement of turtles use up some of the turtle s energy e Rewrite move turtles as follows to move turtles ask turtles right random 360 forward 1 set energy energy As each turtle wanders it will lose one unit of energy at each step 54 Tutorial 3 Procedures NetLogo 3 1 4 User Manual e Switch to the Interface tab now and press the setup button and the go button You ll see the patches turn black as turtles travel over them Monitors Next you will create two monitors in the Interface tab with the Toolbar You make them just like buttons and sliders using the monitor icon on the Toolbar Let s make the first monitor now e Create a monitor using the monitor icon on the Toolbar and click on an open spot in the
3. create link to turtle 1 create link from turtle 1 show __in link with turtle 1 prints turtle 3 show __out link with turtle 1 prints turtle 2 show __link with turtle 1 prints turtle 2 end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details with max agentset with max reporter Takes two inputs on the left an agentset usually turtles or patches On the right a reporter Reports a new agentset containing all agents reporting the maximum value of the given reporter 292 Primitives Dictionary NetLogo 3 1 4 User Manual show count patches with max pxcor 7 prints the number of patches on the right edge See also max one of with min agentset with min reporter Takes two inputs on the left an agentset usually turtles or patches On the right a reporter Reports a new agentset containing only those agents that have the minimum value of the given reporter show count patches with min pycor 7 prints the number of patches on the bottom edge See also min one of without interruption without interruption commands The agent runs all the commands in the block without allowing other agents to interrupt That is other agents are put on hold and do not run any commands until the commands in the block are finished crt 5 ask turtles without interruption type 1 fd 1 type 2
4. 21 22 These are special local variables They hold the current inputs to a reporter or command block for certain primitives for example the current item of a list being visited by foreach or_map Primitives Dictionary 295 NetLogo 3 1 4 User Manual is always equivalent to 1 You may not set these variables and you may not use them except with certain primitives currently foreach map reduce filter sort by and n values See those entries for example usage 296 Primitives Dictionary
5. gt 1212121212 77 because each turtle will output 1 and move then output 2 however ask turtles type 1 fd 1 type 2 gt 1111122222 77 because each turtle will output 1 and move 7 then output 2 word word value value2 word value valuen Concatenates the inputs together and reports the result as a string show word tur tle gt turtle word a 6 gt a6 set directory c foo fish show word directory bar txt gt c foo fish bar txt show word 1 54 8 fishy Primitives Dictionary 293 NetLogo 3 1 4 User Manual gt 1 54 8 fishy show word a b c 1 23 gt abcl23 world width world height world width world height These reporters give the total width and height of the NetLogo world The width and height of the world is the same as max p x y cor min p x y cor 1 See also max pxcor max pycor min pxcor and min pycor wrap color wrap color number wrap color checks whether number is in the NetLogo color range of O to 140 not including 140 itself If it is not wrap color wraps the numeric input to the O to 140 range The wrapping is done by repeatedly adding or subtracting 140 from the given number until it is in the 0 to 140 range This is the same wrapping that is done automatically if you assign an out of range number to the color turtle variable or pcolor patch variable show wrap color 150 gt 10 show wrap color 10 gt 13
6. set default shape wolves wolf create custom wolves initial number wolves create the wolves then initialize their set color balck set size 1 5 easier to see set energy random 2 wolf gain from food setxy random float screen size x random float screen size y display labels do plot end To find a fragment of code in the procedures click on the Find button in the Procedures Toolbar and the Find dialog will appear 000 Find Find sheep Replace with wolves M ignore case M Wrap around Replace All Replace Replace Find Previous Next You may enter either a word or phrase to find or a word or phrase to find and one to replace it with The Ignore case checkbox controls whether the capitalization must be the same to indicate a match If the Wrap around checkbox is checked the entire Procedures tab will be checked for the phrase starting at the cursor position when it reaches the end it will return to the top otherwise only the area from the cursor position to the end of the Procedures tab will be searched The Next and Previous buttons will move down and up to find another occurrence of the search phrase Replace changes the currently selected phrase with the replace phrase and Replace amp Find changes the selected phrase and moves to the next occurrence Replace all will change all instances of the the find phrase in the search area with the repla
7. The reading primitives include ile read file read line file read characters and file at end Note that the file must exist already before you can open it for reading Code Examples File Input Example The primitives for writing are similar to the primitives that print things in the Command Center except that the output gets saved to a file They include i1le print file show file type 110 Programming Guide NetLogo 3 1 4 User Manual and file write Note that you can never overwrite data In other words if you attempt to write to a file with existing data all new data will be appended to the end of the file If you want to overwrite a file use ile delete to delete it then open it for writing Code Examples File Output Example When you are finished using a file you can use the command file close to end your session with the file If you wish to remove the file afterwards use the primitive i le delete to delete it To close multiple opened files one needs to first select the file by using i1e open before closing it Open 3 files file open myfilel txt file open myfile2 txt file open myfile3 txt Now close the 3 files file close file open myfile2 txt file close file open myfilel txt file close Or if you know you just want to close every file you can use file close all Two primitives worth noting are ile write and file read These primitives are designed to easily save
8. Let s look at what you typed in and see what each line of your procedure does eto setup begins defining a procedure named setup e clear al1 resets the world to an initial empty state All the patches turn black and any turtles you might have created disappear Basically it wipes the slate clean for a new model 48 Tutorial 3 Procedures NetLogo 3 1 4 User Manual run ecreate turtles 100 creates 100 turtles They start out standing at the origin that is the center of patch 0 0 e ask turtles tells each turtle to run independently the commands inside the brackets Every command in NetLogo is run by some agent ask is a command too Here the observer is running the ask command itself in turn causing the turtles to run commands e setxy random xcor random ycor is a command using reporters A reporter as opposed to a command reports a result First each turtle runs the reporter random xcor which will report a random number from the allowable range of turtle coordinates along the X axis Then each turtle runs the reporter random ycor same for the Y axis Finally each turtle runs the set xy command with those two numbers as inputs That makes the turtle move to the point with those coordinates e end completes the definition of the setup procedure When you re done typing switch to the Interface tab and press the setup button you made before You will see the turtles scattered around the world Press setup a
9. NetLogo 3 1 4 User Manual show extract hsb red gt 0 0090 0 809 0 843 show extract hsb cyan gt 0 5 0 571 0 769 See also hsb rgb extract rgb extract rgb extract rgb color Reports a list of three values in the range 0 0 to 1 0 representing the levels of red green and blue respectively of the given NetLogo color in the range 0 to 140 show extract rgb red gt 0 843 0 196 0 161 show extract rgb cyan gt 0 329 0 769 0 769 See also rgb hsb extract hsb F face face agent Set the caller s heading towards agent If wrapping is allowed by the topology and the wrapped distance around the edges of the view is shorter than the on screen distance face will use the heading of the wrapped path If the caller and the agent are at the exact same position the caller s heading won t change facexy facexy number number Set the caller s heading towards the point x y If wrapping is allowed by the topology and the wrapped distance around the edges of the view is shorter than the on screen distance and wrapping is allowed facexy will use the heading of the wrapped path If the caller is on the point x y the caller s heading won t change Primitives Dictionary 213 NetLogo 3 1 4 User Manual file at end file at end Reports true when there are no more characters left to read in from the current file that was opened previously with _file open Otherwise reports false file open m
10. inspect clear while most reporters are nouns or noun phrases Commands and reporters built into NetLogo are called primitives The Primitives Dictionary has a complete list of built in commands and reporters Commands and reporters you define yourself are called procedures Each procedure has a name preceded by the keyword to The keyword end marks the end of the commands in the procedure Once you define a procedure you can use it elsewhere in your program Many commands and reporters take inputs values that the command or reporter uses in carrying out its actions Examples Here are two command procedures to setup ca clear the world ert 10 make 10 new turtles end to go ask turtles fd 1 7 all turtles move forward one step rt random 10 Fi and turn a random amount lt random 10 end 86 Programming Guide NetLogo 3 1 4 User Manual Note the use of semicolons to add comments to the program Comments make your program easier to read and understand In this program e setup and go are user defined commands e ca Clear all crt create turtles ask 1t left turn and rt right turn are all primitive commands e random and turtles are primitive reporters random takes a single number as an input and reports a random integer that is less than the input in this case between 0 and 9 turtles reports the agentset consisting of all the turtles We ll explain about agentsets later
11. screen edge x tomin pxcor and all cases of screen edge x to max pxcor and similarly for y Though this is not directly related to the topology changes you may also want to think about whether moving the origin off center makes sense in your model at this time Before 116 Programming Guide NetLogo 3 1 4 User Manual NetLogo 3 1 the world had to be symmetrical around the origin thus the world had to have an odd width and height This is no longer true since you may use any min and max combinations you wish given that the point 0 0 still exists in the world If you are logically only modeling in one or two quadrants or if it makes your code simpler to only use positive numbers you might want to consider changing your model If you ve modeled something that requires and even grid you ll certainly want to remove the programming hacks required to make that possible in the past Code Examples Lattice Gas Automaton Binomial Rabbits Rugby For NetLogo 3 1 we added new primitives which are essential if you change the topology and quite convenient even if you don t random pxcor random pycor random xcor and_random ycor report random values within the range between maximum and minimum x and y In older versions of NetLogo we often relied on wrapping to place turtles randomly across the world by writing set xy random float screen size x random float screen size y However if wrapping is not allowed in one direction or the other this no
12. BehaviorSpace How do measure runs every n ticks Use repeat in your experiment s go commands e g repeat 100 go to measure the run after every 100 model steps Essentially you are making one experiment step equal 100 model steps I m varying a global variable declared in the Procedures tab but it doesn t work Why It s probably because your setup commands or setup procedure are using ca Or clear all causing the values set by BehaviorSpace to be cleared Try using the more specific clearing commands to clear only what you want cleared Programming How is the NetLogo language different from the StarLogoT language How do convert my StarLogoT model to NetLogo We don t have a document that specifically summarizes the differences between these two programs If you have built models in StarLogoT before then we suggest reading the_Programming Guide section of this manual to learn about NetLogo particularly the sections on Ask and Agentsets Looking at some of the sample models and code examples in the Models Library may help as well NetLogo 1 3 1 includes a StarLogoT model converter you just open the model from the File menu and NetLogo will attempt to convert it The converter doesn t do all that great a job though so the result will very likely require additional changes before it will work Note also that the model converter is no longer included in current versions of NetLogo so if you have models you want to
13. NetLogo 3 1 4 User Manual NetLogo 3 1 4 User Manual Table of Contents What 1S od Ro o o sia dis 1 ESTOS ir A A DA AA sd 1 COPyEON LIMA ION A Galea a hee 3 Third party licenses aiii ia ana 3 What s NeW iii ias a arios 7 Version 3 1 4 February 16 2007 h cocccccccccccnoconononnnonnnonnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnniss 7 Version 3 1 3 September 20 200 000 a ies 7 Versi n 3 1 2 August 9 2006 iie tarada a coil ai 7 Version 3 11 June 10 200 iii va ccs wats eresaeae dual a A E aa e aeaa 7 Version 3 1 April 14 2006 ooccccccccccncccnocononenonononononnnnnnnnnnnnnnnnnnnnnnnnnnnonnnnnnnnnnnnnnnnnnnnennnninenis 8 Version 3 0 September 200 aa a AA 10 Version 2 1 December 2004 ooccccocooconccccoconcnccoocononnoncncnnnononcnnnonnnrnnnononrononnonrnnennoncnnenneninnnnes 10 Version 2 0 2 August 2004 coocccccccccccnnccnncnoncnononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnoss 11 Version 2 0 December 2003 oooccccoconcnnccococoncnccncononnoncncnnnononrnnnonnnrnnnononrnnonnonrnnennonrnninnenennonns 11 Version June 200 aaa 11 Version 1 2 March 2003 occccoconcnncccococoncnccoconcnnoncononnononcnnnononnnnnononrnnnononrononnoncnnennoncnnenninanennns 12 Version 1 1 July 2002 seris a E E a e O i aa ES st EEEa 12 Version 1 0 April 2002 ooococcccccconcconcconocononononnnnnnnnnnnnononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnineniness 12 System Requirements 13 System Requir
14. When running headless there are some restrictions e Plotting primitives are non functional However calling them will not produce any ill effects e The movie primitives are not available trying to use them will cause a Java exception e user primitives which query the user for input such as user yes or no will cause a Java exception e Sliders switches and choosers do not enforce constraints on the values they accept For example in the full NetLogo application if you try to set a switch to a value other than true or false the switch will not accept the new value Similarly a chooser enforces that its value is a valid choice and a slider enforces that its value is permitted by its minimum maximum and increment When running headless none of these checks occur We plan to lift these restrictions in a future version of NetLogo The NetLogo API Specification contains further details BehaviorSpace The Controlling API supports running BehaviorSpace experiments headless It does not support running them in BehaviorSpace s GUI although you can write your own BehaviorSpace like Java code to run your own BehaviorSpace like experiments if you want Note that it is definitely not necessary to use the API to do headless BehaviorSpace runs Headless BehaviorSpace is supported directly from the command line with no Java programming at all required See the BehaviorSpace Guide for instructions In most cases the command line su
15. e Then add a go procedure to the Procedures tab ES do move turtles end But what is move turt les ls it a primitive in other words built in to NetLogo like clear a11 is No it s another procedure that you re about to add So far you have introduced two procedures that you added yourself setup and go 50 Tutorial 43 Procedures NetLogo 3 1 4 User Manual e Add the move turtles procedure after the goprocedure to Jo move turtles end to move turtles ask turtles right random 360 forward 1 end Note there are no spaces around the dash in move turtles In Tutorial 2 we used red 2 with spaces in order to subtract two numbers but here we want move turt1les without spaces The combines move and turtles into a single name Here is what each command in the move turtles procedure does e ask turtles says that each turtle should run the commands in the brackets e right random 360 is another command that uses a reporter First each turtle picks a random whole number between 0 and 359 random doesn t include the number you give it as a possible result Then the turtle turns right this number of degrees e forward 1 makes the turtle move forward one step Why couldn t we have just written all of these commands in go instead of in a separate procedure We could have but during the course of building your project it s likely that you ll add many other parts We d like to keep go as sim
16. gt created 4 turtles gt created 6 turtles In the block the variable 2 holds the current value from the input list Here are some more examples of foreach foreach 1 2 3 ask turtles fd 7 turtles move forward 6 patches foreach true false true true ask turtles if fd 1 1 7 turtles move forward 3 patches map is similar to foreach but it is a reporter lt takes an input list and another reporter Note that unlike foreach the reporter comes first like this show map round 1 2 2 2 2 7 7 prints 1 2 3 map reports a list containing the results of applying the reporter to each item in the input list Again use to refer to the current item in the list Here is another example of map show map lt 0 1 1 3 4 2 10 5 prints false true false false true true foreach and map won t necessarily be useful in every situation in which you want to operate on an entire list In some situations you may need to use some other technique such as a loop using repeat Or while or a recursive procedure The_sort by primitive uses a similar syntax to map and foreach except that since the reporter needs to compare two objects the two special variables 1 and 2 are used in place of Here is an example of sort by show sort by 1 lt 2 4 1 3 2 q prints 1124354 100 Programming Guide NetLogo 3 1 4 User Manual Varying Numbers of Inputs Some commands and reporters involving
17. setup and go can be called by other procedures or by buttons Many NetLogo models have a once button that calls a procedure called setup and a forever button that calls a procedure called go In NetLogo you must specify which agents turtles patches or the observer are to run each command If you don t specify the code is run by the observer In the code above the observer uses ask to make the set of all turtles run the commands between the square brackets ca and crt can only be run by the observer fd on the other hand can only be run by turtles Some other commands and reporters such as set can be run by different agent types Here are some more advanced features you can take advantage of when defining your own procedures Procedures with inputs Your own procedures can take inputs just like primitives do To create a procedure that accepts inputs include a list of input names in square brackets after the procedure name For example to draw polygon num sides len pd repeat num sides fd len rt 360 num sides end Elsewhere in the program you could ask turtles to each draw an octagon with a side length equal to its ID number ask turtles draw polygon 8 who Reporter procedures Just like you can define your own commands you can define your own reporters You must do two special things First use to report instead of to to begin your procedure Then in the body of the procedure use report to
18. use redistribution etc 2 resetar tata reta ear estares aaa 173 Is the source code to NetLogo available ii iieeeeeaeeaarereasanananaa 173 Do you offer any workshops or other training opportunities for NetLogo 174 What s the difference between StarLogo MacStarLogo StarLogoT and NetLogo 174 Has anyone built a Modo Tata tials uasthantuamduanebedieG wationeds evades 174 Are NetLogo models runs scientifically reproducible nn nen ennenen 174 Are there any NetLogo textbO0kS ccccccccesssssssececeeeessseeneneeeeeeeeessseseeeeeeeeeeeeessesnaaeess 175 Is NetLogo available in a Spanish version German version your language here VERSION COC A O NR DR at 175 Is NetLogo compiled or interpreted occcconnnnoncnnnccccnnnanononnnncnnnnnnnnnnnncncnnnnccnnnnnnnnnnnos 175 Will NetLogo and NetLogo 3D remain separate erre 175 DOWNIO AGING oasis iio 176 The download form doesn t work for me Can have a direct link to the software 176 Downloading NetLogo takes too long Is it available any other way such as ona AAA fee SF eds oN PP A ee aR A aia PORRA 176 downloaded and installed NetLogo but the Models Library has few or no models init HOW can fix thiS a na a E e a A aa nano nnnininns 176 Can have multiple versions of NetLogo installed at the same time 176 I m on a UNIX system and can t untar the download Why2
19. 1 2 3 1 2 3 2 4 6 3 5 9 gt true false true See also foreach 240 Primitives Dictionary NetLogo 3 1 4 User Manual max max list Reports the maximum number value in the list It ignores other types of items show max values from turtles xcor 7 prints the x coordinate of the turtle which is 5 farthest right in the view max one of max one of agentset reporter Reports the agent in the agentset that has the highest value for the given reporter If there is a tie this command reports one random agent with the highest value If you want all such agents use with max instead show max one of patches count turtles here 7 prints the first patch with the most turtles on it See also_with max max pxcor max pycor max pxcor max pycor These reporters give the maximum x coordinate and maximum y coordinate respectively for patches which determines the size of the world Unlike in older versions of NetLogo the origin does not have to be at the center of the world However the maximum x and y coordinates must be greater than or equal to zero Note You can set the size of the world only by editing the view these are reporters which cannot be set cct 100 setxy random float max pxcor random float max pycor 7 distributes 100 turtles randomly in the 5 first quadrant See also min pxcor min pycor world width and_world height mean Primitives Dictionary 241 NetLog
20. If there are multiple patches that have the same smallest value a random one of those patches will be selected If the patch is located directly to the north south east or west of the patch that the turtle is currently on a multiple of 90 degrees is reported However if the patch is located to the northeast northwest southeast or southwest of the patch that the turtle is currently on the direction the turtle would need to reach the nearest corner of that patch is reported See also_downhill4 uphill uphill4 208 Primitives Dictionary NetLogo 3 1 4 User Manual downhill4 downhill4 patch variable Reports the turtle heading between 0 and 359 degrees as a multiple of 90 degrees in the direction of the minimum value of the variable patch variable of the four patches to the north south east and west of the turtle If there are multiple patches that have the same least value a random patch from those patches will be selected See also_downhill uphill uphill4 dx dy dx dy k Reports the x increment or y increment the amount by which the turtle s xcor or ycor would change if the turtle were to take one step forward in its current heading Note dx is simply the sine of the turtle s heading and dy is simply the cosine If this is the reverse of what you expected it s because in NetLogo a heading of 0 is north and 90 is east which is the reverse of how angles are usually defined in geometry Note In earlier v
21. Reports a list of length size containing values computed by repeatedly running reporter In reporter use to refer to the number of the item currently being computed starting from zero show n values 5 1 gt 1 1 1 1 1 show n values 5 gt 0 1 2 3 4 show n values 3 turtle gt turtle 0 turtle 1 turtle 2 show n values 5 gt 0 1 4 9 16 See also_reduce filter neighbors neighbors4 neighbors neighbors4 Reports an agentset containing the 8 surrounding patches neighbors or 4 surrounding patches neighbors4 show sum values from neighbors count turtles here 7 prints the total number of turtles on the eight 248 Primitives Dictionary NetLogo 3 1 4 User Manual 77 patches around the calling turtle or patch ask neighbors4 set pcolor red turns the four neighboring patches red __ lt breed gt neighbors __ lt breed gt neighbors k Reports the agentset of all the node turtles that have links coming from them to the caller or coming from the caller to them breed links link breed for network links to become friendly node procedure create links to friends show _ link neighbors prints the agentset of agents who are 77 friends with or whom it is friends with end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details __ lt breed gt neighbo
22. Selecting To select an interface element drag a rectangle around it with your mouse A gray border will appear around the element to indicate that it is selected Selecting Multiple Items You can select multiple interface elements at the same time by including them in the rectangle you drag If multiple elements are selected one of them is the key item which means that if you use the Edit or Delete buttons on the Interface Toolbar only the key item is affected The key item is indicated by a darker gray border than the other items Unselecting To unselect all interface elements click the mouse on the white background of the Interface tab To unselect an individual element control click Macintosh or right click other systems the element and choose Unselect from the popup menu Editing To change the characteristics of an interface element select the element then press the Edit button on the Interface Toolbar You may also double click the element once it is selected A third way to edit an element is to control click Macintosh or right click other systems it and choose Edit from the popup menu If you use this last method it is not necessary to select the element first Moving Select the interface element then drag it with your mouse to its new location If you hold down the shift key while dragging the element will move only straight up and down or straight left and right Resizing Select the interface element
23. Some activities don t have a view on the client can t quit a HubNet client You will have to force the client to quit On OS X force quit the application by selecting Force Quit in the Apple menu On Windows press Ctrl Alt Delete to open the Task Manager select HubNet Client and press End Task My computer went to sleep while running a HubNet activity When woke the computer up got an error and HubNet wouldn t work anymore The HubNet server may stop working if the computer goes to sleep If this happens quit the NetLogo application and start over Change the settings on your computer so it won t sleep again My problem is not addressed on this page Please send us an email at_feedback ccl northwestern edu Known Limitations If HubNet malfunctions please send us an email at bugs ccl northwestern edu Please note that e HubNet has not yet been extensively tested with large numbers of clients i e more than about 25 Unexpected results may occur with more clients e Out of memory conditions are not handled gracefully e Sending large amounts of plotting messages to the clients can take a long time e NetLogo does not handle malicious clients in a robust manner in other words it is likely vulnerable to denial of service type attacks e Performance does not degrade gracefully over slow or unreliable network connections 138 HubNet Guide NetLogo 3 1 4 User Manual e If you are on a wireless network or sub LAN the IP addre
24. There are a number of settings associated with the Views There are a few ways of changing the settings by using the control strip along the top edge of the View or by editing the 2D View as described in the Working With Interface Elements section above or pressing the Edit button in the control strip The 3D View has a similar control strip but it looks slightly different and as you may notice a few of the controls are missing However the controls that are present work exactly the same as the 2D View Control Strip Speed 0 Edit The controls in the control strip work as follows e The three sets of black arrows let you change the size of the world When the origin is centered the world will grow in increments of two adding one to the maximum and subtracting one from the minimum If one of the edges is set to 0 the world will grow by one in the other direction to keep the origin along the edge If the origin is at a custom location the black arrows will be disabled e The slider lets you control how fast the model runs this is valuable since some models run so fast that it s hard to see what s going on Interface Guide 73 NetLogo 3 1 4 User Manual e The button with the arrowhead lets you turn turtle shapes on and off If shapes are off turtles appear as colored squares instead of having special shapes The squares are less work for the computer to draw so turning shapes off makes models run faster
25. e Type the text shown here Command Center WA Clear observer gt ask patches i set pcolor yellow J v e Press the return key What happened to the View You may have noticed the background of the View has turned all yellow and the street has disappeared Why didn t the cars turn yellow too Looking back at the command that was written we asked only the patches to change their color In this model the cars are represented by a different kind of agent called turtles Therefore the cars did not received these instructions and thus did not change What happened in the Command Center You may have noticed that the command you just typed is now displayed in the white box in the middle of the Command Center as shown below Command Center y observer gt ask patches set pcolor yellow observer gt v e Type in the white box at the bottom of the Command Center the text shown below 38 Tutorial 2 Commands NetLogo 3 1 4 User Manual Command Center Clear observer gt ask patches set pcolor yellow observer gt ask turtles a set color brown J ba Was the result what you expected Your View should have a yellow background with a line of brown cars in the middle The NetLogo world is a two dimensional world that is made up of turtles patches and an observer The patches create the ground in which the turtles can move around on and the observer is a being that oversee everythin
26. gt 91 vl vw Ia la 264 Primitives Dictionary NetLogo 3 1 4 User Manual random xcor random ycor random xcor random ycor Reports a random floating point number from the allowable range of turtle coordinates along the given axis x or y Turtle coordinates range from min pxcor 0 5 inclusive to max pxcor 0 5 exclusive horizontally vertically substitute y for x ask turtles 77 move each turtle to a random point setxy random xcor random ycor See also_random pxcor random pycor read from string read from string string Interprets the given string as if it had been typed in the Command Center and reports the resulting value The result may be a number list string or boolean value or the special value nobody Useful in conjunction with the_user input primitive for converting the user s input into usable form show read from string 3 read from string 5 gt 8 show length read from string 1 2 3 gt 3 crt read from string user input Make how many turtles 7 the number of turtles input by the user are created reduce reduce reporter list Reduces a list from left to right using reporter resulting in a single value This means for example that reduce 1 22 1 2 3 4 is equivalent to 1 2 3 4 If listhas a single item that item is reported It is an error to reduce an empty list In reporter use 1 and 2 to refer to the two objects b
27. on machines when a graphical display is not available Note the user of the server flag to tell Java to optimize performance for server type applications we recommend this flag for best performance in most situations Note the use of Xmx to specify a maximum heap size of 512 megabytes If you don t specify a maximum heap size you will get your VM s default size which may be unusably small 512 megabytes is an arbitrary size which should be more than large enough for most models you can specify a different limit if you want Note also that Xms is used to specify a larger than default initial heap size This helps some models run faster by making garbage collection more efficient The mode1 argument is used to specify the model file you want to open The experiment argument is used to specify the name of the experiment you want to run At the time you create an experiment setup in the GUI you assign it a name Here s another example that shows some additional optional arguments java server Xmsl16M Xmx512M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo N xperiment experiment2 max pxcor 100 N min pxcor 100 max pycor 100 N min pycor 100 no results Note the use of the optional max pxcor max pycor etc arguments to specify a different world size than that saved in the model It s also possible for the experiment setup to specify values for the world dimensions if
28. part of the shape will appear on the other edge of the view Turtles themselves are points that take up no space so they cannot be on both sides of the world at once but in the view 114 Programming Guide NetLogo 3 1 4 User Manual they appear to take up space because they have a shape Wrapping also affects how the view looks when you are following a turtle On a torus wherever the turtle goes you will always see the whole world around it Ea 1 2 A0 2 a ye 2 2 1 2 2 2 2 2 31 1 0 1 1 1 2 1 72 1 1 0 0 0 1 0 2 0 o 1 1 0 1 1 1 2 1 2 1 Whereas in a box or cylinder the world has edges so the areas past those edges show up in the view as gray 1 1 0 1 1 0 0 0 1 1 MQ 1 1 1 Code Example Termites Perspective Demo torus Ants Perspective Demo box Instead of 3 0 s settings that only control the appearance of wrapping in the view NetLogo 3 1 has settings that control whether the world actually wraps or not that is whether opposite edges are in fact connected These new wrapping settings determine the world topology that is whether the world is a torus box or cylinder This affects the behavior and not just the visual appearance of the Programming Guide 115 NetLogo 3 1 4 User Manual model In the past model authors were required to write extra code to simulate a box world with the aid of special no wrap primitives No wrap
29. replace item index string1 string2 On a list replaces an item in that list index is the index of the item to be replaced starting with 0 The 6th item in a list would have an index of 5 Note that replace item is used in conjunction with set to change a list Likewise for a string but the given character of string1 removed and the contents of string2 spliced in instead 268 Primitives Dictionary NetLogo 3 1 4 User Manual show replace item 2 2 7 4 5 15 gt 2 7 15 5 show replace item 1 sat lo gt slot report report value Immediately exits from the current to report procedure and reports value as the result of that procedure report and to report are always used in conjunction with each other See to report for a discussion of how to use them reset perspective rp reset perspective The observer stops watching following or riding any turtles or patches If it wasn t watching following or riding anybody nothing happens In the 3D view the observer also returns to its default position above the origin looking straight down See also_follow ride watch reset timer reset timer Resets the global clock to zero See also timer reverse reverse list reverse string Reports a reversed copy of the given list or string show mylist 5 mylist is 2 7 4 Bob set mylist reverse mylist 5 mylist now is Bob 4 7 2 show reverse string gt gnirts rgb rgb red
30. set the pen size turtle variable to a different number before drawing or erasing In new turtles the variable is set to 1 0 Here s some turtles which have made a drawing over a grid of randomly shaded patches Notice how the turtles cover the lines and the lines cover the patch colors The pen size used here was 2 0 The stamp command lets a turtle leave an image of itself behind in the drawing and stamp erase lets it remove the pixels below it in the drawing To erase the whole drawing use the observer commmand clear drawing You can also use clear al1 which clears everything else too Importing an image Programming Guide 113 NetLogo 3 1 4 User Manual The observer command import drawing command allows you to import an image file from disk into the drawing import drawing is useful only for providing a backdrop for people to look at If you want turtles and patches to react to the image you should use import pcolors instead Comparison to other Logos Drawing works somewhat differently in NetLogo than some other Logos Notable differences include e New turtles pens are up not down e Instead of using a fence command to confine the turtle inside boundaries in NetLogo you edit the world and turn wrapping off e There is no screen color bgcolor or setbg You can make a solid background by coloring the patches e g ask patches set pcolor blue Drawing features not supported by NetLogo e There is no windo
31. to setup ca create mice 50 ask mice set color white create frogs 50 ask frogs set color green show breed of one of mic 77 prints mice show breed of one of frogs 7 prints frogs end show mouse 1 7 prints mouse 1 Primitives Dictionary 199 NetLogo 3 1 4 User Manual show frog 51 7 prints frog 51 show turtle 51 7 prints frog 51 See also_globals patches own turtles own lt breeds gt own create lt breeds gt create custom lt breeds gt lt breeds gt at lt breeds gt here but first bf but last bl but first list but first string but last list but last string When used on a list but first reports all of the list items of list except the first and but last reports all of the list items of list except the last On strings but first and but last report a shorter string omitting the first or last character of the original string 7 mylist is 2 4 6 5 8 12 set mylist but first mylist 7 mylist is now 4 6 5 8 12 set mylist but last mylist 7 mylist is now 4 6 8 show but first string 77 prints trang show but last string 7 prints strin C can move can move distance Reports true if the calling turtle can move distance in the direction it is facing without violating the topology reports false otherwise It is equivalent to patch ahead distance nobody 200 Primitives Dictionary NetLogo 3 1 4 User Manual carefully carefully commands1 command
32. try App app open models Sample Models Earth Science Fire nlogo catch java io IOException ex ex printStackTrace 13 App app command set density 62 APp app command random seed 0 App app command setup App app command repeat 50 go System out println App app report burned trees catch Exception ex ex printStackTrace In order to compile and run this Net Logo jar from the NetLogo distribution must be in the classpath Note the use of Event Queue invokeAndWait to ensure that a method is called from the right thread This is because most of the methods on the App class may only be called some certain threads Most of the methods may only be called from the AWT event queue thread but a few methods such as commmand may only be called from threads other than the AWT event queue thread such as in this example the main thread Rather than continuing to discuss this example in full detail we refer you to the NetLogo API Specification which documents all of the ins and outs of the classes and methods used above Additional methods are available as well Example headless The example code in this case is very similar to the previous example but with methods on an instance of the HeadlessWorkspace Class substituted for static methods on App import org nlogo headless HeadlessWorkspace public class Example2 public static void main
33. value If reporter reports true runs commands If reporter reports false runs commands2 The reporter may report a different value for different agents so some agents may run commands1 while others run commands2 ask patches ifelse pxcor gt 0 set pcolor blue set pcolor red 7 the left half of the view turns red and the right half turns blue See also if ifelse value ifelse value ifelse value reporter reporter reporter2 Reporter must report a boolean true or false value If reporter reports true the result is the value of reporter If reporter reports false the result is the value of reporter2 This can be used when a conditional is needed in the context of a reporter where commands such as ifelse are not allowed ask patches set pcolor Primitives Dictionary 227 NetLogo 3 1 4 User Manual ifelse value pxcor gt 0 blue red 1 1 7 the left half of the view turns red and 7 the right half turns blue show n values 10 ifelse value lt 5 0 1 gt 000001111 1 show reduc ifelse valu 71 gt 22 21 7221 1 32 53 8 3 2 1 gt 8 See also if ifelse import drawing import drawing filename Reads an image file into the drawing scaling it to the size of the world while retaining the original aspect ratio of the image The image is centered in the drawing The old drawing is not cleared first Agents cannot sense the drawing so the
34. you can control when the user sees view updates You might want to change lots of things on the view behind the user s back so to speak then make them visible to the user all at once Two your model will run faster when view updating is off so if you re in a hurry this command will let you get results faster Note that normally you don t need to use no display for this since you can also use the on off switch in view control strip to freeze the view Note that display and no display operate independently of the switch in the view control strip that freezes the view See also display nobody nobody This is a special value which some primitives such as turtle one of max one of etc report to indicate that no agent was found Also when a turtle dies it becomes equal to nobody 250 Primitives Dictionary NetLogo 3 1 4 User Manual Note Empty agentsets are not equal to nobody If you want to test for an empty agentset use_any You only get nobody back in situations where you were expecting a single agent not a whole agentset set other one of other turtles her if other nobody set color of other red not not boolean Reports true if boolean is false otherwise reports false if not color blue fd 10 7 all non blue turtles move forward 10 steps nsum nsum4 nsum patch variable nsum4 patch variable SS A For each patch reports the sum of the values of patch variable in the 8 surround
35. 1 s new topology feature Making this change may require other changes to your model though See the_Topology section of the Programming Guide for a thorough discussion of how to convert your model to take advantage of this new feature If your model is behaving strangely or incorrectly perhaps it s because in NetLogo 3 1 agentsets are now always in random order In prior versions of NetLogo agentsets were always in a fixed order If your code depended on that fixed order then it won t work anymore in 3 1 How to fix your model to work with randomized agentsets depends on the details of what your code is doing In some situations it is helpful to use the sort or sort by primitives to convert an agentset random order into a list of agents fixed order See Lists of agents in the Lists section of the Programming Guide Why do get a runtime error when use setxy random world width random world height It worked before Many models made in NetLogo 3 0 or earlier use this code to scatter turtles randomly using either random Or random float It only works if world wrapping is on Why Because when wrapping is on you can set coordinates of turtles to numbers beyond the edge of the world and NetLogo will wrap the turtle to the other side But in worlds that don t wrap setting the x or y coordinates of a turtle to a point outside the bounds of the world causes a runtime error The world wrap settings are new in NetLogo 3 1 See the Topology s
36. 122 123 128 129 129 9 pink 135 130 131 132 133 20136 137 138 139 139 9 To get a color that doesn t have its own name you just refer to it by a number instead or by adding or subtracting a number from a name For example when you type set color red this does the same thing as if you had typed set color 15 And you can get a lighter or darker version of the same color by using a number that is a little larger or a little smaller as follows e Choose patches from the popup menu in the Command Center or use the tab key e Type set pcolor red 2 The spacing around the is important By subtracting from red you make it darker e Type set pcolor red 2 By adding to red you make it lighter You can use this technique on any of the colors listed in the chart Agent Monitors and Agent Commanders In the previous activity we used the set command to change the colors of all the cars But if you recall the original model contained one red car amongst a group of blue cars Let s look at how to change only one car s color 42 Tutorial 2 Commands NetLogo 3 1 4 User Manual e Press setup to get the red car to reappear e If you are on a Macintosh hold down the Control key and click on the red car On other operating systems click on the red car with the right mouse button e From the popup menu that appears choose inspect turtle 0 A turtle monitor for that car will appear Taking a closer look
37. 272 Primitives Dictionary NetLogo 3 1 4 User Manual gt 1 2 3 show sentence 1 2 3 gt 1 2 3 show sentence 1 2 3 4 gt 1 2 3 4 show sentence 1 21 3 4 gt 1 2 3 4 show sentence 1 2 3 4 51 3 3 7 gt 1234567 set set variable value Sets variable to the given value Variable can be any of the following e An global variable declared using globals e The global variable associated with a slider switch or chooser e A variable belonging to the calling agent e If the calling agent is a turtle a variable belonging to the patch under the turtle e An expression of the form VARIABLE of agent e A local variable created by the let command set current directory set current directory string Sets the current directory that is used by the primitives file delete file exists and file open The current directory is not used if the above commands are given an absolute file path This is defaulted to the user s home directory for new models and is changed to the model s directory when a model is opened Note that in Windows file paths the backslash needs to be escaped within a string by using another backslash CN The change is temporary and is not saved with the model Note in applets this command has no effect since applets are only allowed to read files from the same directory on the server where the model is stored set current directory C NetLogo Assume it is a
38. 43 Procedures NetLogo 3 1 4 User Manual e Switch back to the Interface tab e Press the setup button Voila A lush NetLogo landscape complete with turtles and green patches appears After seeing the new setup procedure work a few times you may find it helpful to read through the procedure definitions again Turtle variables So we have some turtles running around on a landscape but they aren t doing anything with it Let s add some interaction between the turtles and the patches We ll make the turtles eat grass the green patches reproduce and die The grass will gradually grow back after it is eaten We ll need a way of controlling when a turtle reproduces and dies We ll determine that by keeping track of how much energy each turtle has To do that we need to add a new turtle variable You ve already seen built in turtle variables like color To make a new turtle variable we add a turtles own declaration at the top of the Procedures tab before all the procedures Call it energy turtles own energy Tutorial 3 Procedures 53 NetLogo 3 1 4 User Manual to go move turtles eat grass end Let s use this newly defined variable energy to allow the turtles to eat e Switch to the Procedures tab e Rewrite the go procedure as follows to go move turtles Sat grass end e Add a new eat grass procedure CO sst grass ask turtles if pcolor green set pcolor black set energy energy 10
39. 5 create dogs 1 ask dogs show count cats here gt See also_other turtles here turtles on lt breeds gt on turtles on agent turtles on agentset lt breeds gt on agent lt breeds gt on agentset Reports an agentset containing all the turtles that are on the given patch or patches or standing on the same patch as the given turtle or turtles ask turtles if not any turtles on patch ahead 1 fd 1 ask turtles if not any turtles on neighbors die of loneliness If the name of a breed is substituted for turtles then only turtles of that breed are included See also_turtles from turtles own lt breeds gt own turtles own var1 var2 lt breeds gt own var1 var2 The turtles own keyword like the globals breed lt breeds gt own and patches own keywords can only be used at the beginning of a program before any function definitions It defines the variables belonging to each turtle If you specify a breed instead of turtles only turtles of that breed have the listed variables More than one breed may list the same variable breed cats cat breed dogs dog breed hamsters hamster turtles own eyes legs 7 applies to all breeds 286 Primitives Dictionary NetLogo 3 1 4 User Manual cats own fur kittens hamsters own fur cage dogs own hair puppies See also_globals patches own breed lt breeds gt own type type value Prints value in
40. For example NetLogo 2 0 has a different generator than NetLogo 1 3 did 2 0 s generator which is known as the Mersenne Twister is faster and generates numbers that are statistically more random than 1 3 s Java s built in linear congruential generator To create a number suitable for seeding the random number generator use the new seed reporter new seed creates a seed evenly distributed over the space of possible seeds based on the current date and time And it never reports the same number twice in a row Code Example Random Seed Example If you don t set the random seed yourself NetLogo sets it to a value based on the current date and time There is no way to find out what random seed it chose so if you want your model run to be reproducible you must set the random seed yourself ahead of time The NetLogo primitives with random in their names random random float and so on aren t the only ones that use pseudo random numbers Many other operations also make random choices For example agentsets are always in random order one of and n of choose agents randomly the sprout command creates turtles with random colors and headings and the downhill reporter chooses a random patch when there s a tie All of these random choices are governed by the random seed as well so model runs can be reproducible 104 Programming Guide NetLogo 3 1 4 User Manual Turtle shapes In NetLogo turtle shapes are vector shapes They are built u
41. JVM Note that the 3D view is not available in applets System Requirements 3D View NetLogo s 3D view is a new feature and hasn t been tested on every configuration Below is information about configurations that we have tested so far Operating Systems We ve tested the 3D view on e Linux 2 6 8 Debian i386 e Linux 2 6 8 Debian amd64 e Mac OS X 10 3 9 10 4 3 note Java 1 4 2 is required e Windows 2000 e Windows XP If you use the 3D view on an operating system that we haven t tested we d like to hear about it Please let us know at feedback Occl northwestern edu Please include the information in the System section of About NetLogo Graphics Cards We ve tested the 3D view on many different graphics cards and controllers including e ATI Radeon 7500 e ATI Radeon 9200 e ATI Radeon 9600 e ATI Radeon 9800 XT e ATI Radeon IGP 345 e ATI Radeon Mobility e ATI FireGL V3100 e Intel 82830M e nVidia GeForce MX e nVidia GeForce FX 5200 e nVidia GeForce FX Go5650 e nVidia Quadro NVS 14 System Requirements NetLogo 3 1 4 User Manual If you use the 3D view with a graphics card that we haven t tested we d like to hear about it Please let us know at feedback ccl northwestern edu Please include the information in the System section of About NetLogo Fullscreen mode Fullscreen mode does not work with some graphics cards and controllers including the ATI Radeon IGP 345 and the Intel 82845 Some users with
42. Manual e interface fixes double clicking outside a bracket or parenthesis in the editor now selects all of the text between the matching brackets or parentheses when shapes are off shapes consisting of a single line now still draw as lines not squares fixed some incorrectly worded compiler error messages involving primitives that can take a variable number of inputs such as list and sentence 4 fixed Windows only bug where the Procedures menu had trouble showing very large number of procedure names 4 fixed Mac only bug where pasting text from another application could cause a compiler error e BehaviorSpace changes you can now use the st op command in an experiment s go commands or in the procedure called by your experiment s go commands to stop a model run the same way it works to stop a forever button you can now choose to save no results at all the Abort button is now more often able to halt a stuck model the Procedures tab is now always recompiled before an experiment begins e HubNet changes new activities Bug Hunters Camouflage Walking Disease Doctors Function Guppy Spots improved activities Predator Prey Game formerly Herbivore Carnivore Root Beer Game formerly Beer Game e API changes documentation now recommends using the server VM for best performance Version 3 0 September 2005 e 3D view for 2D models e System Dynamics Modeler e follow ride and watch commands for tracking par
43. Manual HubNet Control Center e OS HubNet Control Center i Name everreau Clients Activity Disease Seth Matthew Server address 129 105 107 236 Josh Port number 9173 Craig Esther Andrei Settings Y Mirror 2D view on clients Mirror plots on clients experimental Y Broadcast serv dress Debug Kick Local 11 35 27 Craig joined from 129 105 107 236 51949 11 35 38 Esther joined from 129 105 107 236 51952 0 11 35 49 Andrei joined from 129 105 107 236 51955 a v The HubNet Control Center lets you interact with the HubNet server It displays the name activity address and port number of your server The Mirror 2D View checkbox controls whether the HubNet participants can see the view on their clients assuming there is a view in the client setup The Mirror plots checkbox controls whether participants will receive plot information The client list on the right displays the names of clients that are currently connected to you activity To remove a participant from the activity select their name in the list and press the Kick button To launch your own HubNet client press the Local button this is particularly useful when you are debugging an activity The lower part of the Control Center displays messages when a participant joins or leaves the activity To broadcast a message to all the participants click on the field at the bottom type your message and press Broadcast Message Troubleshooting
44. National Science Foundation REPP and ROLE Programs grant numbers REC 9814682 and REC 0126227 Third party licenses For random number generation NetLogo uses the MersenneTwisterFast class by Sean Luke The copyright for that code is as follows Copyright c 2003 by Sean Luke Portions copyright c 1993 by Michael Lecuyer All rights reserved Redistribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met e Redistributions of source code must retain the above copyright notice this list of conditions and the following disclaimer e Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution e Neither the name of the copyright owners their employers nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE COPYRIGHT OWNERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO
45. NetLogo 1 3 1 Mac OS X e OS X version 10 2 6 or later 10 3 or later is recommended e 128 MB RAM 256 MB RAM strongly recommended On OS X the Java Virtual Machine is supplied by Apple as part of the operating system OS X 10 3 includes an appropriate JVM OS X 10 2 users must install Java 1 4 1 Update 1 which is available from Apple through Software Update For OS X 10 3 users installing Java 1 4 2 Update 1 is recommended for improved application reliability The update is available from Apple through Software Update Mac OS 8 and 9 These operating systems are no longer supported by the current version of NetLogo MacOS 8 and 9 users should download NetLogo 1 3 1 instead We will continue to support NetLogo 1 3 1 Other platforms NetLogo should work on any platform on which a Java Virtual Machine version 1 4 1 or later is available and installed Version 1 5 0_05 or later is preferred If you have trouble please contact us see above System Requirements 13 NetLogo 3 1 4 User Manual System Requirements Saved Applets NetLogo models saved as Java applets should work on any web browser and platform on which a Java Virtual Machine version 1 4 1 or later is available If you have trouble please contact us see above On Mac OS X the Internet Explorer browser does not make use of the 1 4 1 JVM so it cannot run saved applets We suggest using Apple s Safari browser instead or another web browser which uses the newer
46. OK in the Plot dialog box y E AAA Plot Name Totals X axis label time Xmin 0 Xmax 10 Y axis label totals Ymin 0 Y max 10 Y Autoplot Plot Pens Choose Pen to Edit turtles 2 _ Delete Color black 38000 A egend Enter a name for the pen 62 Tutorial 43 Procedures NetLogo 3 1 4 User Manual Note that when you create the plot you can also set the minimum and maximum values on the X and Y axes You ll want to leave the Autoplot checkbox checked so that if anything you plot exceeds the minimum and maximum values for the axes the axes will automatically grow so you can see all the data e Setup and run the model again You can now watch the plot being drawn as the model is running Your plot should have the general shape of the one below though your plot might not look exactly the same Remember that we left Autoplot on This allows the plot to readjust itself when it runs out of room If you forget which pen is which click on the Pens label on the top right corner of the plot You might try running the model several times to see what aspects of the plot are the same and which are different Global variables To make comparisons between plots from one model run and another it is often useful to do the comparison for the same length of model run Learning how to stop or start an action at a specific time can help make this happen by stopping the model at the same point each mode
47. Windows Machine file open myfile txt Opens file C NetLogo myfile txt Primitives Dictionary 273 NetLogo 3 1 4 User Manual set current plot set current plot plotname Sets the current plot to the plot with the given name a string Subsequent plotting commands will affect the current plot set current plot pen set current plot pen penname The current plot s current pen is set to the pen named penname a string If no such pen exists in the current plot a runtime error occurs set default shape set default shape turtles string set default shape breed string ig Specifies a default initial shape for all turtles or for a particular breed When a turtle is created or it changes breeds it shape is set to the given shape This command doesn t affect existing turtles only turtles you create afterwards The specified breed must be either turtles or a breed defined by the breed keyword and the specified string must be the name of a currently defined shape In new models the default shape for all turtles is default Note that specifying a default shape does not prevent you from changing an individual turtle s shape later turtles don t have to be stuck with their breed s default shape create turtles 1 new turtle s shape is default create cats 1 7 new turtle s shape is default set default shape turtles circle create turtles 1 new turtle s shape is circle create cats 1 7 new turtle s shape
48. a monitor called Location the tags for these interface elements will be as follows interface elemen tag t Move Left Move Left p size step size in one step ste all in one ste all in one step Location Location Be aware that this causes the restriction that you can only have one interface element with a specific name Having more than one interface element with the same Display Name in the client interface will cause unpredictable behavior For instance if we had a monitor called Milk Supply and a plot named Milk Supply when we send data to the client using the tag Milk Supply the client will just pick either the plot or the monitor to give the data to If you wish to have a View in the client for a model the view in the client and the one in the NetLogo model must have the same number of patches and the same patch size If they do not the view on the client will not display information sent by the server If you wish to make a client without a view in the client you will have to hand edit the file after you have finished adding all the other interface elements in NetLogo To do this open the client file in a text editor such as Notepad on Windows or TextEdit on Macs You should see a file that starts with something similar to this add model procedures her CHSHCHS HE GRAPHICS WINDOW 321 10 636 325 17 E7 9 0 ih 10 0 0 HubNet Authoring Guide 145 NetLogo 3 1 4 User Manual CC W
49. and other information You may want to read the Information tab before running a model or you might want to just start experimenting then look at the Information tab later What would happen to the sheep population if there was more initial sheep and less initial wolves at the beginning of the simulation e Turn the grass switch off e Set the initial number sheep slider to 100 e Set the initial number wolves slider to 20 e Press setup and then go e Let the model run for about 100 time ticks Try running the model several times with these settings What happened to the sheep population Did this outcome surprise you What other sliders or switches can be adjusted to help out the sheep population e Set initial number sheep to 80 and initial number wolves to 50 This is close to how they were when you first opened the model e Set sheep reproduce to 10 0 e Press setup and then go e Let the model run for about 100 time ticks What happened to the wolves in this run When you open a model all the sliders and switches are on a default setting If you open a new model or exit the program your changed settings will not be saved unless you choose to save them 30 Tutorial 1 Models NetLogo 3 1 4 User Manual Note in addition to sliders and switches some models have a third kind of setting called a chooser The Wolf Sheep Predation doesn t have any of these though Gathering
50. autoplot Reports true if auto plotting is on for the current plot false otherwise auto plot off auto plot on auto plot off auto plot on This pair of commands is used to control the NetLogo feature of auto plotting in the current plot Primitives Dictionary 197 NetLogo 3 1 4 User Manual Auto plotting will automatically update the x and y axes of the plot whenever the current pen exceeds these boundaries It is useful when wanting to display all plotted values in the current plot regardless of the current plot ranges B back bk back number The turtle moves backward by number steps If number is negative the turtle moves forward Turtles using this primitive can move a maximum of one unit per time increment So bk 0 5 and bk 1 both take one unit of time but bk 3 takes three If the turtle cannot move backward number steps because it is not permitted by the current topology the turtle will complete as many steps of 1 as it can and stop See also forward jump can move beep beep Emits a beep Note that the beep is emitted immediately so several beep commands in succession will only produce a single audible sound Example beep 7 emits one beep repeat 3 beep 77 emits 3 beeps at the exact same time 7 so you only hear one sound repeat 3 beep wait 0 1 produces 3 beeps in succession separated by 1 10th of a second both ends _ both ends Reports the agentset of the 2 nodes connect
51. be lost or cut off The pitch of a melodic instrument is specified by a key number The keys on the keyboard are numbered consecutively from 0 to 127 where 0 is the left most key Middle C is key number 60 The loudness of an instrument is specified by a velocity which represents the force with which the keyboard key is depressed Velocity ranges from 0 to 127 where 64 is the standard velocity A higher velocity results in a louder sound Using the Sound Extension The sound extension comes preinstalled To use the extension in your model add a line to the top of your procedures tab extensions sound jar For more information on NetLogo extensions see the Extensions Guide Please note that the NetLogo extensions facility is under development and is still considered experimental so the syntax is likely to change in a future version of NetLogo Models saved as applets using Save as Applet on NetLogo s File menu cannot make use of extensions that require additional external jars We plan to fix this in a future release For examples that use the sound extension see the Sound section under Code Examples in the NetLogo Models Library Primitives drums instruments play drum play note play note later start note stop note stop instrument stop music drums drums Reports a list of the names of the 47 drums for use with play drum instruments Sound Extension 165 NetLogo 3 1 4 User Manual instru
52. button can be pressed at a time If this happens the buttons take turns which means that only one button runs at a time Each button runs its code all the way through once while the other buttons wait then the next button gets its turn In the following examples setup is a once button and go is a forever button Example 1 The user presses setup then presses go immediately before the setup has popped back up Result setup finishes before go starts Example 2 While the go button is down the user presses setup Result the go button finishes its current iteration Then the setup button runs Then go starts running again Example 3 The user has two forever buttons down at the same time Result first one button runs its code all the way through then the other runs its code all the way through and so on alternating Note that if one button gets stuck in an infinite loop then no other buttons will run Buttons and view updates When you edit a button there is a checkbox called Force view update after each run Below the checkbox is a note that reads Checking this box produces smoother animation but may make the button run more slowly Most of the time it s enough to know that if you prefer smooth animation check the box and if you prefer speed uncheck it In some models the difference is dramatic in others it s hardly noticeable It depends on the model What follows is a more detailed explanati
53. can be saved as applets to be embedded in web pages note some features are not available from applets such as some extensions and the 3D view What is NetLogo Copyright Information Copyright 1999 2007 by Uri Wilensky All rights reserved The NetLogo software models and documentation are distributed free of charge for use by the public to explore and construct models Permission to copy or modify the NetLogo software models and documentation for educational and research purposes only and without fee is hereby granted provided that this copyright notice and the original author s name appears on all copies and supporting documentation For any other uses of this software in original or modified form including but not limited to distribution in whole or in part specific prior permission must be obtained from Uri Wilensky The software models and documentation shall not be used rewritten or adapted as the basis of a commercial software or hardware product without first obtaining appropriate licenses from Uri Wilensky We make no representations about the suitability of this software for any purpose It is provided as is without express or implied warranty To reference this software in academic publications please use Wilensky U 1999 NetLogo http ccl northwestern edu netlogo Center for Connected Learning and Computer Based Modeling Northwestern University Evanston IL The project gratefully acknowledges the support of the
54. ce eveanens acucbecncgcadahsedusaideas ana a O needs 253 out lt breed gt neighbors rn nr rn rre 254 QUI lt DreCAS LO iii tadas 254 output print output show output type OutoUt Write ooooooococococonooncnoncnonononcnnnnnnnononononons 255 DN dedo dear SENSE ce TR q A Do RN OR OPE OT RO AAA A E E 255 Dat ee cece ccieachitaselinnetdtactioenceeesteacascleapecatealvtveteteaseltalsl tans Otucnevusdeouadrapeacdousstites Ietaetehalenees 255 patch ahead NA 255 palch al cette aaa tudes A A wean tala eae 256 patch at heading and distance errar arara ease rre 256 NetLogo 3 1 4 User Manual Table of Contents Primitives Dictionary Patch Ori A ia 256 patch left and ahead patch right and ahlead cccccccnnonococnnoncconnnnononnnnnnnnnnnnnnnnnnnnnnos 256 PalcheS ms aaa EE canada Do e EO ERES E a A SR A A cits 257 DCI EO A a a in 257 PATCNAESSO Witt AAA A aaa 257 PEO A A A ORDER SD 258 pen down pd pen erase pe pen up Ple cccccccncccnnccnnnnnnnnnnenenenenennnennnnnnnnrnnrrnnr ran r ranas 258 PEN MOdE ii o iaa 258 PEN SIZO AA AAA da 258 O O E a 259 ETERON EEE AE E asada 259 DOE E A E E A 259 POE AMM A A a ei Sah 259 plot pen down ppd plot pen up PU ccccccnccncccncnnnnnnnnnnnnnnenenenenenennnnnnnnnnnrnnnr ran r ranas 260 LL PR 260 DIGIKY AQMRRRSRRDRS ED SARRO T io 260 plot x min plot x max plot y Min plot y max eee 260 DOSIS A maining avai eed SAT rend e a Rd 260 DN ae 2
55. commands _ create lt breeds gt to agentset commands _ create lt breeds gt from agentset commands _ create lt breeds gt with agentset commands Used for creating link turtles between agents Links are special turtles A link turtle s size is always equal to the distance between the two node turtles it links together Its heading is always equal to the heading from one node turtle to the other Its location is always halfway between the two node turtles Their default shape is link Primitives Dictionary 203 NetLogo 3 1 4 User Manual _ create lt breed gt with creates an undirected link between the caller and agent _ create lt breed gt to creates a link from the caller to agent create lt breed gt from creates a link from agentto the caller When the plural form of the breed name is used an agentset is expected instead of an agent and links are created between the caller and all agents in the agentset The command block is the set of commands each newly formed link runs The links are created all at once then run one at a time in random order A node cannot be linked to itself Also you cannot have more than one undirected link of the same breed between the same two nodes nor can you have more than one directed link of the same breed going in the same direction between two nodes breed links link breed for network links to make friend frd node procedure 7 Creates a friendship link between
56. equal to the value given in the plot command in the first case the number of turtles and in the second case the number of green patches As the pens move they each draw a line In order for set current plot Totals to work you ll have to add a plot to your model in the Interface tab then edit it so its name is the same name used in the procedures Even one extra space in the name will throw it off it must be exactly the same in both places e Create a plot using the plot icon on the Toolbar and click on an open spot in the Interface e Set its Name to Totals see image below e Set the X axis label to time e Set the Y axis label to total Tutorial 3 Procedures 61 NetLogo 3 1 4 User Manual Name Totals X axis label time Xmin 0 X max 10 Y axis label totals Y min 0 Y max 10 M Autoplot Plot Pens Choose Pen to Edit default HJ Color black E Mode Line Interval 1 0 M Show in Legend Cancer 50 Next you will need to create two pens e With the Plot dialog box still open press the Create button in the Plot dialog to create a new pen e Enter the name of this pen as turtles and press OK in the Enter Pen Name dialog see image below e Press the Create button in the Plot dialog again to create a second new pen e Enter the name of this pen as grass and press OK in the Enter Pen Name dialog see image below e Select the color for this pen and change it to green e Select
57. error if it is given coordinates outside the world This is a common situation when the model is simulating an infinite plane and turtles outside the view should simply be hidden let new x new value of xcor let new y new value of ycor ifelse patch at new x xcor new y ycor nobody hide turtle setxy new x new y show turtle Several models in the Models Library use this technique Gravitation N Bodies and Electrostatics are good examples By using a different topology you get diffuse for free which was fairly difficult to do in the past Each patch diffuses and equal amount of the diffuse variable to each of its neighbors if it has fewer than 8 neighbors or 4 if you are using diffuse4 the remainder stays on the diffusing patch This means that the overall sum of patch variable across the world remains constant If you had special code to handle diffuse then you can remove it However if you want the diffuse matter to still fall off the edges of the world as it would on an infinite plane you still need to clear the edges each step as in the Diffuse Off Edges Example Links Links are an experimental part of NetLogo and primitives related to Links are subject to change Because links are experimental the names of the primitives begin with two underscores A link is a special turtle connecting two other turtles The two turtles are called nodes A link turtle s size is always equal to the distance between the
58. file write file read characters file read characters number Reports the given number of characters from an opened file as a string If there are fewer than that many characters left it will report all of the remaining characters Note that it will return every character including newlines and spaces Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter filge at end to determine if you are at the end of the file file open myfile txt print file read characters 8 Current line in file is Hello World gt Hello Wo See also file open 216 Primitives Dictionary NetLogo 3 1 4 User Manual file read line file read line Reads the next line in the file and reports it as a string It determines the end of the file by a carriage return an end of file character or both in a row It does not return the line terminator characters Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter file at end to determine if you are at the end of the file file open myfile txt print file read line gt Hello World See also file open file show file show value Prints value to an opened file preceded by the calling agent and followed by a carriage return The calling agent is included to help you keep track of what agents are producing
59. find another group For example if the tolerance level is set at 25 then males are only comfortable in groups that are less than 25 female and females are only comfortable in groups that are less than 25 male As individuals become uncomfortable and leave groups they move into new groups which may cause some people in that group to become uncomfortable in turn This chain reaction continues until everyone at the party is comfortable in their group Note that in the model tolerance is not fixed You the user can use the tolerance slider to try different tolerance percentages and see what the outcome is when you start the model over again How to start over 1 If the go button is pressed black then the model is still running Press the button again to stop it 2 Adjust the tolerance slider to a new value by dragging its red handle 3 Press the setup button to reset the model 4 Press the go button to start the model running again Challenge As the host of the party you would like to see both men and women mingling within the groups Adjust the tolerance slider on the side of the view to get all groups to be mixed as an end result To make sure all groups of 10 have both sexes at what level should we set the tolerance Test your predictions on the model Can you see any other factors or variables that might affect the male to female ratio within each group Make predictions and test your
60. format Switches turn on off a separate set of directions These directions are usually not necessary for the model to run but might add another dimension to the model Turning the grass switch on affected the outcome of the model Prior to this run the growth of the grass stayed constant This is not a realistic look at the predator prey relationship so by setting and turning on a grass growth rate we were able to model all three factors sheep wolf and grass populations Tutorial 1 Models 29 NetLogo 3 1 4 User Manual Another type of setting is called a slider Sliders are a different type of setting then a switch A switch has two values on or off A slider has a range of numeric values that can be adjusted For example the initial number sheep slider has a minimum value of 0 and a maximum value of 250 The model could run with O sheep or it could run with 250 sheep or anywhere in between Try this out and see what happens As you move the marker from the minimum to the maximum value the number on the right side of the slider changes this is the number the slider is currently set to Let s investigate Wolf Sheep Predation s sliders e Read the contents of the Information tab located above the toolbar to learn what each of this models sliders represents The Information tab is extremely helpful for gaining insight into the model Within this tab you will find an explanation of the model suggestions on things to try
61. four neighboring patches to the north south east and west not to the diagonal neighbors diffuse4 chemical 0 5 7 each patch diffuses 50 of its variable 7 Chemical to its neighboring 4 patches Thus each patch gets 1 4 of 50 of the chemical from each neighboring patch display display Causes the current view to be updated immediately Also undoes the effect of the no display command so that if display updates were suspended by that command they will resume no display ask turtles jump 10 set color blue set size 5 display turtles move change color and grow with none of 5 their intermediate states visible to the user only their final state Even if no display was not used display can still be useful because ordinarily NetLogo is free to skip some view updates so that fewer total updates take place so that models run faster This command lets you force a view update so whatever changes have taken place in the world are visible to the user ask turtles set color red display ask turtles set color blue 7 turtles turn red then blue use of display forces 7 red turtles to appear briefly There is exception to the immediately rule if the command is used by an agent that is running without interruption such as via the without interruption command inside a procedure defined using to report or inside a command such as hatch sprout or cct then the view update tak
62. green blue Reports a number in the range 0 to 140 not including 140 itself that represents the given color specified in the RGB spectrum in NetLogo s color space Primitives Dictionary 269 NetLogo 3 1 4 User Manual All three inputs should be in the range 0 0 to 1 0 The color reported may be only an approximation since the NetLogo color space does not include all possible colors See_hsb for a description of what parts of the HSB color space NetLogo colors cover this is difficult to characterize in RGB terms show rgb 0 0 0 gt 0 0 black show rgb 0 1 0 1 0 gt 85 0 cyan See also extract rgb hsb and extract hsb ride ride turtle gt Set the perspective to turtle Every time turtle moves the observer also moves Thus in the 2D View the turtle will stay at the center of the view In the 3D view it is as if looking through the eyes of the turtle If the turtle dies the view will return to the default position See also reset perspective watch follow subject ride me ride me k Asks the observer to ride the calling turtle See also_ride right rt right number The turtle turns right by number degrees If numberis negative it turns left round round number Reports the integer nearest to number 270 Primitives Dictionary NetLogo 3 1 4 User Manual If the decimal portion of number is exactly 5 the number is rounded in the positive direction Note that rounding in the posit
63. have defined breeds you can go on and make the different breeds behave differently For example you could have breeds called sheep and wolves and have the wolves try to eat the sheep You define breeds using the breed keyword at the top of the Procedures tab before any procedures breed wolves wolf breed sheep a sheep You can refer to a member of the breed using the singular form just like the turtle reporter When printed members of the breed will be labeled with the singular name Some commands and reporters have the plural name of the breed in them such as create lt breeds gt Others have the singular name of the breed in them such as lt breed gt neighbor The order in which breeds are declared is also the order order in which they are layered in the view So breeds defined later will appear on top of breeds defined earlier in this example sheep will be drawn over wolves When you define a breed such as sheep an agentset for that breed is automatically created so that all of the agentset capabilities described above are immediately available with the sheep agentset The following new primitives are also automatically available once you define a breed create sheep create custom sheep cct sheep for short hatch sheep sprout sheep sheep here sheep at sheep on and is a sheep Also you can use sheep own to define new turtle variables that only turtles of the given breed have 94
64. is a built in turtle variable It holds the turtle s id number an integer greater than or equal to zero You cannot set this variable a turtle s id number never changes When NetLogo starts or after you use the clear all or_clear turtles commands new turtles are created with ids in order starting at 0 If a turtle dies though a new turtle may eventually be assigned the same id number that was used by the dead turtle Example show values from turtles with color red who 7 prints a list of the id numbers of all red turtles Primitives Dictionary 291 NetLogo 3 1 4 User Manual in the Command Center ca cct 100 ifelse who lt 50 set color red set color blue 7 turtles 0 through 49 are red turtles 50 through 99 are blue You can use the turtle reporter to retrieve a turtle with a given id number See also turtle with agentset with reporter Takes two inputs on the left an agentset usually turtles or patches On the right a boolean reporter Reports a new agentset containing only those agents that reported true in other words the agents satisfying the given condition show count patches with pcolor red 7 prints the number of red patches __ lt breed gt with __ lt breed gt with agent Report the link turtle from the agent to the caller or from the caller to the agent If no link exists then it reports nobody to find friendship with ca ect 2 ask turtle 0
65. is separately editable We re not sure when this will happen Is NetLogo compiled or interpreted Short answer interpreted but we are working on a compiler Long answer NetLogo does include a compiler but the compiler does not produce native code or even Java byte code lt produces a custom intermediate representation that can be interpreted more efficiently than the original code However we are working on a new compiler that will generate Java byte code Once that is done NetLogo will qualify as compiled not interpreted Since Java virtual machines have just in time compilers that in turn compile Java byte code all the way to native code the new compiler should substantially improve the speed of NetLogo We are not sure when the new compiler will be ready Will NetLogo and NetLogo 3D remain separate No The split is temporary Eventually a single unified version of NetLogo will support both 2D and 3D modeling We will be sure to design the 3D world support in such a way that it doesn t get in the way when you are building 2D models Models built in NetLogo 3D Preview 1 may require some small changes in order to run in the FAQ Frequently Asked Questions 175 NetLogo 3 1 4 User Manual eventual unified version Downloading The download form doesn t work for me Can I have a direct link to the software Please write us at bugsccl northwestern edu and we ll either fix the problem with the form or provide you with an alte
66. is turtle only patches gt set color red E e Type set pcolor red instead and press return We call color and pcolor variables Some commands and variables are specific to turtles and some are specific to patches For example the color variable is a turtle variable while the pcolor variable is a patch variable Go ahead and practice altering the colors of the turtles and patches using the set command and these two variables To be able to make more changes to the colors of turtles and patches or shall we say cars and backgrounds we need to gain a little insight into how NetLogo deals with colors In NetLogo all colors have a numeric value In all of the exercises we have been using the name of the color This is because NetLogo recognizes 16 different color names This does not mean that NetLogo only recognizes 16 colors There are many shades in between these colors that can be used too Here s a chart that shows the whole NetLogo color space Tutorial 2 Commands 41 NetLogo 3 1 4 User Manual black 0 white 9 9 gray 5 8 9 9 9 red 15 19 199 orange 25 20 22 23 28 29 29 9 brown 35 30 32 33 e E 39 399 yellow 45 40 4 43 48 49 49 9 green 55 50 52 53 58 59 59 9 lime 65 60 62 63 68 69 699 turquoise 75 70 722 73 78 79 79 9 cyan 85 80 82 83 8 88 89 89 9 sky 95 90 91 92 E 98 99 99 9 blue 105 100 101 102 103 108 109 109 9 violet 115 110 111 112 113 117 118 119 1199 magenta 125 120 121
67. line in file File is in reading mode file open C NetLogo myfile out txt 7 assuming Windows machine file print Hello World File is in writing mode See also file close file print file print value Prints value to an opened file followed by a carriage return The calling agent is not printed before the value unlike file show Primitives Dictionary 215 NetLogo 3 1 4 User Manual Note that this command is the file i o equivalent of print and_file open needs to be called before this command can be used See also file show file type and file write file read file read This reporter will read in the next constant from the opened file and interpret it as if it had been typed in the Command Center It reports the resulting value The result may be a number list string boolean or the special value nobody Whitespace separates the constants Each call to file read will skip past both leading and trailing whitespace Note that strings need to have quotes around them Use the command file write to have quotes included Also note that the file open command must be called before this reporter can be used and there must be data remaining in the file Use the reporter file at end to determine if you are at the end of the file file open myfile data print file read 5 7 Next value is the number 1 gt 6 print length file read 7 Next value is the list 1 2 3 4 gt 4 See also file open and
68. lists and strings may take a varying number of inputs In these cases in order to pass them a number of inputs other than their default the primitive and its inputs must be surrounded by parentheses Here are some examples show list 1 2 gt 1 2 show list 1 2 3 4 gt 1 2 3 4 show list gt Note that each of these special commands has a default number of inputs for which no parentheses are required The primitives which have this capability are list word sentence map and foreach Lists of agents Earlier we said that agentsets are always in random order a different random order every time If you need your agents to do something in a fixed order you need to make a list of the agents instead There are two primitives that help you do this sort and sort by Both sort and sort by can take an agentset as input The result is always a new list containing the same agents as the agentset did but in a particular order If you use sort on an agentset of turtles the result is a list of turtles sorted in ascending order by who number If you use sort on an agentset of patches the result is a list of patches sorted left to right top to bottom If you need descending order instead you can combine reverse with sort for example reverse sort turtles If you want your agents to be ordered by some other criterion than the standard ones sort uses you ll need to use sort by instead Here s an example
69. longer works you get a runtime error for trying to place turtles outside the world Regardless of topology it is simpler and more straight forward to use setxy random xcor random ycor instead To convert a model to use a topology you must first decide what settings best describe the world If the answer is not immediately obvious to you based on the real world a room is a box a wire is a cylinder there are a few clues that will help you If anywhere in the code you are checking the bounds of the world or if some patches are not considered neighbors of the patches on the other side of the view it is likely that you are not using a torus If you check bounds in both the x and y directions it s a box in the x direction only a horizontal cylinder the y a vertical cylinder If you use no wrap primitives you are probably not modeling a torus however be careful with this criterion if you use a mix of no wrap and wrap primitives It may be that you were using a no wrap primitive for a visual element but the rest of the NetLogo world is still a torus After you ve determined the topology and changed it by editing the view you may have to make a few small changes to the code If you ve decided that the world is a torus you probably don t have to make any changes at all If your model only uses patch neighbors and diffuse you probably will not need to make many changes If your model has turtles that move around your next step is to determine what h
70. measure of repulsion between the nodes It is the force that 2 nodes ata distance of 1 unit will exert on each other The repulsion effect tries to get the nodes as far as possible from each other in order to avoid crowding and the spring effect tries to keep them at about a certain distance from the nodes they are connected to The result is the laying out of the whole network in a way which highlights 236 Primitives Dictionary NetLogo 3 1 4 User Manual relationships among the nodes and at the same time is crowded less and is visually pleasing If agentset is an agentset of patches an error is thrown The layout algorithm is based on the Fruchterman Reingold layout algorithm More information about this algorithm can be obtained_here breed links link breed nodes node to make a triangle set default shape nodes circle create custom nodes 3 ask turtle 0 create links with turtles with who of self 0 ask turtle 1 create link with turtle 2 repeat 30 __layout spring nodes 0 2 5 1 lays the nodes in a triangle end This command is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details __layout tutte __layout tutte agentset anchor agentset radius The turtles in anchor agentset are placed in a circle layout with the given radius There should be at least 3 agents in the anchor agentset The turtles in agentset
71. might find more convenient than using the menu You might try typing turt les gt pen down into the Command Center and then pressing the go button Also inside the move turtles procedure you can try changing right random 360 to right random 45 Play around It s easy and the results are immediate and visible one of NetLogo s many strengths When you feel you ve done enough experimenting for now you re ready to continue improving the model you are building Patches and variables Now we ve got 100 turtles aimlessly moving around completely unaware of anything else around them Let s make things a little more interesting by giving these turtles a nice background against which to move e Go back to the setup procedure We can rewrite it as follows to setup clear all setup patches setup turtles end e The new definition of setup refers to two new procedures To define setup patches add this to setup patches ask patches set pcolor green end The setup patches procedure sets the color of every patch to green to start with A turtle s color variable is color a patch s is pcolor The only part remaining in our new setup that is still undefined is setup turt les e Add this procedure too to setup turtles create turtles 100 ask turtles setxy random xcor random ycor end Did you notice that the new setup turt les procedure has most of the same commands as the old setup procedure 52 Tutorial
72. model built up stage by stage with every step explained along the way Agents and procedures In Tutorial 2 you learned how to use the command center and agent monitors to inspect and modify agents and make them do things Now you re ready to learn about the real heart of a NetLogo model the Procedures tab You ve already used types of agents you can give commands to in NetLogo patches turtles and the observer Patches are stationary and arranged in a grid Turtles move over that grid The observer oversees everything that s going on and does whatever the turtles and patches can t do for themselves All three types of agents can run NetLogo commands All three can also run procedures A procedure combines a series of NetLogo commands into a single new command that you define You will now learn to write procedures that make turtles move eat reproduce and die You will also learn how to make monitors sliders and plots The model we ll build is a simple ecosystem model not unlike parts of Wolf Sheep Predation from Tutorial 1 Making the setup button To start a new model select New from the File menu Then begin by creating a setup button e Click the Button icon in the toolbar at the top of the Interface tab e Click wherever you want the button to appear in the empty white area of the Interface tab e A dialog box for editing the button opens Type setup in the box labeled Commands e Press the OK button when y
73. name of the client that just logged off See the HubNet Authoring Guide for details and instructions hubnet fetch message hubnet fetch message If there is any new data sent by the clients this retrieves the next piece of data so that it can be accessed by hubnet message hubnet message source and hubnet message tag This will cause an error if there is no new data from the clients See the_HubNet Authoring Guide for details hubnet message hubnet message Reports the message retrieved by hubnet fetch message See the HubNet Authoring Guide for details hubnet message source hubnet message source Reports the name of the client that sent the message retrieved by hubnet fetch message See the HubNet Authoring Guide for details hubnet message tag 224 Primitives Dictionary NetLogo 3 1 4 User Manual hubnet message tag Reports the tag that is associated with the data that was retrieved by hubnet fetch message For Calculator HubNet this will report one of the variable names set with the hubnet set client interface primitive For Computer HubNet this will report one of the Display Names of the interface elements in the client interface See the HubNet Authoring Guide for details hubnet message waiting hubnet message waiting This looks for a new message sent by the clients It reports true if there is one and false if there is not See the HubNet Authoring Guide for details hubnet reset hubnet reset Star
74. number commands This turtle creates number new turtles each identical to its parent and asks the new turtle s that have been hatched to run commands You can use the commands to give the new turtles different colors headings or whatever In our case we run one command We set the energy for the newly hatched turtle to be 50 When each turtle runs check death it will check to see if its energy is less or equal to O If this is true then the turtle is told to die die is a NetLogo primitive When each patch runs regrow grass it will check to see if a random integer from 0 to 99 is less than 3 If so the patch color is set to green This will happen 3 of the time on average for each patch since there are three numbers 0 1 and 2 out of 100 possible that are less than 3 e Switch to the Interface tab now and press the setup and go buttons You should see some interesting behavior in your model now Some turtles die off some new turtles are created hatched and some grass grows back This is exactly what we set out to do If you continue to watch your monitors in your model you will see that the count turtles and green patches monitors both fluctuate Is this pattern of fluctuation predictable Is there a relationship between the variables It d be nice if we had a easier way to track the changes in the model behavior over time NetLogo allows us to plot data as we go along That will be our next step Plotting To make
75. of NetLogo The details of the agent scheduling mechanism and the random number generator may change between NetLogo versions and other changes bugfixes in the engine language changes and so forth may also affect the behavior of your model Then again they may not e We have expended every effort to make NetLogo model runs fully reproducible but of course this can never truly be an iron clad guarantee due to the possibility of random hardware failure and also due to the possibility of human error in the design of your model NetLogo your Java VM your hardware and so on Are there any NetLogo textbooks We at the CCL have hoped to write several NetLogo textbooks for quite some time These could be aimed at different audiences such as middle school high school undergraduate course in modeling or complexity practical guide for interested adults Unfortunately we have not yet been able to find the time to make these happen If people from the user community would like to collaborate on such a venture please let us know We would welcome it Is NetLogo available in a Spanish version German version your language here version etc At present NetLogo is available only in English We plan to eventually make it possible for users to produce their own foreign language packs for NetLogo and share them with each other In order to do this we need to separate all of the English text from the rest of the source code so that
76. of all variables for a model both built in and user defined including all observer turtle and patch variables from an external file named by the given string The file should be in the format used by the export world primitive Note that the functionality of this primitive is also directly available from NetLogo s File menu When using import world to avoid errors perform these steps in the following order 1 Open the model from which you created the export file 2 Press the Setup button to get the model in a state from which it can be run 3 Import the file 4 If you want press Go button to continue running the model from the point where it left off If you wish to import a file from a location other than the model s location you may include the full path to the file you wish to import See export world for an example in cone agentset in cone distance angle This reporter lets you give a turtle a cone of vision in front of itself The cone is defined by the two inputs the vision distance radius and the view angle The view angle may range from 0 to 360 and is centered around the turtle s current heading If the angle is 360 then in cone is equivalent to in radius in cone reports an agentset that includes only those agents from the original agentset that fall in the cone including the agent itself The distance to a patch is measured from the center of the patch ask turtles ask patches in cone 3 60 set
77. of values one for each agent in the agentset Then use one of NetLogo s list primitives to do something with the list See the Lists section below For example to find out how rich the richest turtle is you could say show max values from turtles sum assets e Use turtles from and patches from reporters to make new agentsets by gathering together the results reported by other agents Programming Guide 93 NetLogo 3 1 4 User Manual This only scratches the surface see the Models Library for many more examples and consult the Primitives Guide and Primitives Dictionary for more information about all of the agentset primitives More examples of using agentsets are provided in the individual entries for these primitives in the NetLogo Dictionary In developing familiarity with programming in NetLogo it is important to begin to think of compound commands in terms of how each element passes information to the next one Agentsets are an important part of this conceptual scheme and provide the NetLogo developer with a lot of power and flexibility as well as being more similar to natural language Code Example Ask Agentset Example Earlier we said that agentsets are always in random order a different random order every time If you need your agents to do something in a fixed order you need to make a list of the agents instead See the Lists section below Breeds NetLogo allows you to define different breeds of turtles Once you
78. release of computer HubNet formerly HubNet required the TI Navigator calculator network to operate now you can use it over TCP IP with networks of laptop or desktop computers e new primitives and other language improvements e display of coordinates when mousing over plots Version 1 1 July 2002 e Save as Applet lets you embed your model in any web page e printer support e Procedures menu e scrollable Interface tab e contextual menus in Interface tab e new primitives Version 1 0 April 2002 e initial release after a series of betas 12 What s New System Requirements NetLogo is designed to run on almost any type of computer but some older or less powerful systems are not supported The exact requirements are summarized below lf you have any trouble with NetLogo not working on your system we would like to offer assistance Please write bugs ccl northwestern edu System Requirements Application On all systems approximately 25MB of free hard drive space is required Windows e Windows NT 98 ME 2000 or XP e 64 MB RAM or probably more for NT 2000 XP You can choose to include a suitable Java Virtual Machine when downloading NetLogo If you want to use a JVM that you install separately yourself it must be version 1 4 1 or later 1 5 0_05 or later is preferred Windows 95 is no longer supported by the current version of NetLogo Windows 95 users should use NetLogo 1 3 1 instead We will continue to support
79. report the value you want to report to report absolute value number ifelse number gt 0 report number report 0 number Programming Guide 87 NetLogo 3 1 4 User Manual end Variables Variables are places to store values such as numbers A variable can be a global variable a turtle variable or a patch variable If a variable is a global variable there is only one value for the variable and every agent can access it But each turtle has its own value for every turtle variable and each patch has its own value for every patch variable Some variables are built into NetLogo For example all turtles have a color variable and all patches have a pcolor variable The patch variable begins with p so it doesn t get confused with the turtle variable If you set the variable the turtle or patch changes color See next section for details Other built in turtle variables including xcor ycor and heading Other built in patch variables include pxcor and pycor There is a complete list here You can also define your own variables You can make a global variable by adding a switch or a slider to your model or by using the globals keyword at the beginning of your code like this globals clock You can also define new turtle and patch variables using the turtles own and patches own keywords like this turtles own energy speed patches own friction These variables can then be used freely i
80. s New NetLogo 3 1 4 User Manual randomized agent ordering every agentset is now always in random order a different random order each time you use it world topologies 0 the world isn t always a torus anymore by turning vertical and horizontal wrapping on or off you can choose between a torus a rectangle or a vertical or horizontal cylinder 0 using primitives ending in nowrap is no longer necessary just turn off world wrapping instead 0 new can move reporter lets turtles sense the world edges 0 screen edge x and screen edge y have been renamed to max pxcor and max pycor and new min pxcor and min pycor primitives have been added 0 screen size x and screen size y have been renamed to world width and world height see the Topology section of the Programming Guide for more information new experimental suite of link primitives useful for network models and others see Links sections of Programming Guide and Primitives Dictionary model authors can now specify the singular form of a breed name 0 the new syntax for declaring each breed is e g breed wolves wolf you can ask for a breeded turtle by who number e g wolf 0 0 in model output breeded turtles also appear as e g wolf 0 0 added new reporter e g is wolf 0 this form also appears elsewhere in the user interface e g when picking a turtle from the view in turtle monitors and so on new command stamp erase new__tieand__untie primitives allow t
81. section Usually the observer uses ask to ask all turtles or all patches to run commands You can also use ask to have an individual turtle or patch run commands The reporters turtle patch and patch at are useful for this technique For example to setup ca ere 3 make 3 turtles ask turtle 0 tell the first one bao A 5 to go forward ask turtle 1 tell the second one set color green 77 to become green ask turtle 2 tell the third one te 90 5 to turn right ask patch 2 2 7 ask the patch at 2 2 set pcolor blue jj to become blue ask turtle 0 ask the first turtle ask patch at 1 0 j to ask patch to the east set pcolor red to become red end Every turtle created has an ID number The first turtle created has ID 0 the second turtle ID 1 and so forth The turt le primitive reporter takes an ID number as an input and reports the turtle with that ID number The patch primitive reporter takes values for pxcor and pycor and reports the patch with those coordinates And the patch at primitive reporter takes offsets distances in the x and y directions from the first agent In the example above the turtle with ID number 0 is asked to get the patch east and no patches north of itself You can also select a subset of turtles or a subset of patches and ask them to do something This involves a concept called agentsets The next section explains this concept in detail Agentset
82. step on any of the patches along their path L label label k This is a built in turtle variable It may hold a value of any type The turtle appears in the view with the given value attached to it as text You can set this variable to add change or remove a turtle s label See also label color plabel plabel color Example ask turtles set label who all the turtles now are labeled with their id numbers ask turtles set label all turtles now are not labeled label color label color This is a built in turtle variable It holds a number greater than or equal to O and less than 140 This number determines what color the turtle s label appears in if it has a label You can set this variable to change the color of a turtle s label See also label plabel plabel color Example ask turtles set label color red all the turtles now have red labels last Primitives Dictionary 233 NetLogo 3 1 4 User Manual last list last string On a list reports the last item in the list On a string reports a one character string containing only the last character of the original string __ layout circle _ layout circle agentset radius __layout circle ist of turtles radius Arranges the given turtles in a circle centered on the patch at the center of the world with the given radius If the world has an even size the center of the circle is rounded down to the nearest patch The t
83. the interaction of many individuals NetLogo lets students open simulations and play with them exploring their behavior under various conditions It is also an authoring environment which enables students teachers and curriculum developers to create their own models NetLogo is simple enough that students and teachers can easily run simulations or even build their own And it is advanced enough to serve as a powerful tool for researchers in many fields NetLogo has extensive documentation and tutorials It also comes with a Models Library which is a large collection of pre written simulations that can be used and modified These simulations address many content areas in the natural and social sciences including biology and medicine physics and chemistry mathematics and computer science and economics and social psychology Several model based inquiry curricula using NetLogo are currently under development NetLogo can also power a classroom participatory simulation tool called HubNet Through the use of networked computers or handheld devices such as Texas Instruments TI 83 calculators each student can control an agent in a simulation Follow_this link for more information NetLogo is the next generation of the series of multi agent modeling languages that started with StarLogo It builds off the functionality of our product_StarLogoT and adds significant new features and a redesigned language and user interface NetLogo is written in J
84. the larger the number the lighter the shade of color But if range2 is less than range the color scaling is inverted If number is less than range1 then the darkest shade of color is chosen If number is greater than range2 then the lightest shade of color is chosen Note for color shade is irrelevant e g green and green 2 are equivalent and the same spectrum of colors will be used ask turtles set color scale color red age 0 50 7 colors each turtle a shade of red proportional 7 to its value for the age variable self self x Reports this turtle or patch self and myself are very different self is simple it means me myself means the turtle or patch who asked me to do what I m doing right now ask turtles with self myself die 7 this turtle kills all other turtles See also_myself semicolon comments After a semicolon the rest of the line is ignored This is useful for adding comments to your code text that explains the code to human readers Extra semicolons can be added for visual effect NetLogo s Edit menu has items that let you comment or uncomment whole sections of code sentence se sentence value value2 sentence value valuen Makes a list out of the values If any value is a list its items are included in the result directly rather than being included as a sublist Examples make this clearer show sentence 1 2 gt 1 2 show sentence 1 2 3
85. the node on which this 7 procedure was called and the node frd __create link to frd set color blue end to become friendly node procedure 7 makes this node link with an agentset of turtles create links to friends end This command is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details create turtles crt create lt breeds gt create turtles number create lt breeds gt number gt Creates number new turtles New turtles start at position 0 0 are created with the 14 primary colors and have headings from 0 to 360 evenly spaced crt 100 ask turtles fd 10 makes an evenly spaced circle If the create lt breeds gt form is used the new turtles are created as members of the given breed 204 Primitives Dictionary NetLogo 3 1 4 User Manual create custom turtles cct create custom lt breeds gt cct lt breeds gt create custom turiles number commands create custom lt breeds gt number commands Creates number new turtles of the given breed if specified New turtles start at position 0 0 New turtles are created with the 14 primary colors and have headings from 0 to 360 evenly spaced The new turtles immediately run commands This is useful for giving the new turtles a different color heading or whatever The new turtles are created all at once then run one at a time in random order breed can
86. the special quantities infinity or not a number will cause a runtime error In NetLogo integers and floating point numbers are interchangeable in the sense that as long as you stay within legal ranges it is never an error to supply 3 when 3 0 is expected or 3 0 when 3 is expected In fact 3 and 3 0 are considered equal according to the equals operator If a floating point number is supplied in a context where an integer is expected the fractional part is simply discarded So for example crt 3 5 creates three turtles the extra 0 5 is ignored Scientific notation Very large or very small floating point numbers are displayed by NetLogo using scientific notation Examples O gt show 0 000000000001 observer 1 0E 12 O gt show 50000000000000000000 0 observer 5 0E19 Numbers in scientific notation are distinguished by the presence of the letter E for exponent It means times ten to the power of so for example 1 0E 12 means 1 0 times 10 to the 12 power O gt show 1 0 10 12 observer 1 0E 12 You can also use scientific notation yourself in NetLogo code O gt show 3 0E6 observer 3000000 0 102 Programming Guide NetLogo 3 1 4 User Manual O gt show 3 0E7 observer 3 0E7 O gt show 8 0E 3 observer 0 0080 O gt show 8 0E 4 observer 8 0E 4 These examples show that numbers are displayed using scientific notation if the exponent is less than 3 or greater than 6 When enterin
87. therefore we need to refer to them some other way Remember patches are arranged on a coordinate system Two numbers are needed to plot a point on a graph an x axis value and a y axis value Patch locations are designated in the same way as plotting a point e Open a patch monitor for any patch The monitor shows that for the patch in the picture its pxcor variable is 11 and its pycor variable is 4 If we go back to the analogy of the coordinate plane and wanted to plot this point the point would be found in the lower left quadrant of the coordinate plane where x 11 and y 4 To tell this particular patch to change color use its coordinates e In the bottom of the patch monitor enter set pcolor blue and press return Typing a command in a turtle or patch monitor addresses only that turtle or patch You can also talk to a single patch from the Command Center e In the Command Center enter ask patch 11 4 set pcolor green and press return What s Next At this point you may want to take some time to try out the techniques you ve learned on some of the other models in the Models Library Tutorial 2 Commands 45 NetLogo 3 1 4 User Manual In Tutorial 3 Procedures you can learn how to alter and extend existing models and build your own models 46 Tutorial 2 Commands Tutorial 3 Procedures NetLogo User Manual This tutorial leads you through the process of building a complete
88. they are specified by the experiment setup then there is no need to specify them on the command line 132 BehaviorSpace Guide NetLogo 3 1 4 User Manual Note also the use of the optional no results argument to specify that no output is to be generated This is useful if the experiment setup generates all the output you need by some other means such as exporting world files or writing to a text file Yet another example java server Xms16M Xmx512M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo xperiment experiment2 table table output csv spreadsheet spreadsheet output csv The optional table lt filename gt argument specifies that output should be generated in a table format and written to the given file as CSV data If is specified as the filename than the output is sent to the standard system output stream Table data is written as it is generated with each complete run The optional spreadsheet lt filename gt argument specified that soreadsheet output should be generated and written to the given file as CSV data If is specified as the filename than the output is sent to the standard system output stream Spreadsheet data is not written out until all runs in the experiment are finished Note that it is legal to specify both table and spreadsheet and if you do both kinds of output file will be generated The default output behavior when no outpu
89. through them When the tutorials are printed out there s more room on your computer screen for the NetLogo model you re looking at Sample Model Wolf Sheep Predation We ll open one of the Sample Models and explore it in detail Let s try a biology model Wolf Sheep Predation a predator prey population model e Open the Models Library from the File menu NetLogo MIES Edit Tools Zoon a New 3N tl 0 3 Open Models Library 3M 3 Save 3S E Save AS Save As Applet Print dE P e Choose Wolf Sheep Predation from the Biology section and press Open The Interface tab will fill up with lots of buttons switches sliders and monitors These interface elements allow you to interact with the model Buttons are blue they set up start and stop the model Sliders and switches are green they alter model settings Monitors and plots are beige they display data If you d like to make the window larger so that everything is easier to see you can use the zoom menu at the top of the window When you first open the model you will notice that the view is empty all black To begin the model you will first need to set it up Tutorial 1 Models 27 NetLogo 3 1 4 User Manual e Press the setup button What do you see appear in the view e Press the go button to start the simulation As the model is running what is happening to the wolf and sheep populations e Press the go button to stop the mod
90. to be copied into your Java Runtime Environment or JRE installation If you are using the version of NetLogo which comes with its own Java VM then your JRE installation is in the jre subdirectory of the NetLogo folder Otherwise it is in a directory like c 132sdk1 4 The files comm jar and javax comm properties must be copied into the 1ib folder of the JRE installation The files win32comm d11 must be copied to the bin folder of the JRE installation The file PlatformSpecific has more detailed instructions Linux and others There is no official implementation of the Java Communications API for Linux You can use the RXTX implementation Kevin Hester has written some installation instructions Using the GoGo Extension The GoGo Extensions comes preinstalled To use the extension in your model add a line to the top of your procedures tab extensions gogo jar After loading the extension see what ports are available by typing the following into the command center show gogo ports You can open the serial port the GoGo Board is connected to with the gogo open command and see if the board is responding with the ping reporter On Windows gogo open COMI show ping On Linux gogo open dev ttyS01 show ping For more information on NetLogo extensions see the Extensions Guide Models saved as applets using Save as Applet on NetLogo s File menu cannot use the Gogo extension since applets can t u
91. two node turtles Its heading is always equal to the heading from one node turtle to the other Its location is always halfway between the two node turtles When one of the nodes moves the link turtle will automatically change its heading size and location There are two flavors of links undirected and directed A directed link is out of or from one node and into or to another node The relationship of a parent to a child could be modeled as a directed link An undirected link appears the same to both nodes each node has a link with another node The relationship between spouses or siblings could be modeled as an undirected link 118 Programming Guide NetLogo 3 1 4 User Manual All link turtles must have a breed This means you must define at least one breed in your model using the breed keyword Link turtles can only be created using specific commands The commands create lt breed gt with and __create lt breeds gt with creates undirected links the commands __create lt breed gt to _ create lt breeds gt to _ create lt breed gt from and create lt breeds gt from create directed links breed links link breed nodes node to setup ca create custom nodes 2 fd 10 ask node 0 __create link with node 1 end Once the first link of any breed has been created directed or undirected all links of that breed must match it s impossible to have two links of the same breed where one i
92. unless they are also members of anchor agentset are then laid out in the following manner Each turtle is placed at centroid or barycenter of the polygon formed by its linked neighbors The centroid is like a 2 dimensional average of the coordinates of the neighbors The purpose of the circle of anchor agentset is to prevent all the turtles from collapsing down to one point After a few iterations of this the layout will stabilize If agentset is an agentset of patches an error is thrown This layout is named after the mathematician William Thomas Tutte who proposed it as a method for graph layout breed links link to make a tree set default shape turtles circle ect 6 Primitives Dictionary 237 NetLogo 3 1 4 User Manual ask turtle 0 create link with turtle 1 create link with turtle create link with turtle 3 N ask turtle 1 create link with turtle 4 create link with turtle 5 place all the turtles with just one neighbor on the perimeter of a circle and then place the remaining turtles inside this circle spread between their neighbors repeat 10 __layout tutte turtles turtles with count __link neighbors 1 12 0 end This command is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details left It left number The turtle turns left by number degrees If number is
93. use the plus operator like this tur tle gt turtle If you need to embed a special character in a string use the following escape sequences e n newline e t tab e double quote e backslash Output This section is about output to the screen Output to the screen can also be later saved to a file using the export output command If you need a more flexible method of writing data to external files see the next section File I O The basic commands for generating output to the screen in NetLogo are print show type and write These commands send their output to the Command Center For full details on these four commands see their entries in the Primitives Dictionary Here is how Programming Guide 109 NetLogo 3 1 4 User Manual they are typically used e print is useful in most situations e show lets you see which agent is printing what e type lets you print several things on the same line e write lets you print values in a format which can be read back in using file read A NetLogo model may optionally have an output area in its Interface tab separate from the Command Center To send output there instead of the Command Center use the_output print output show output type and output write commands The output area can be cleared with the clear output command and saved to a file with export output The contents of the output area will be saved by the export world command The import
94. used in models as a quick way to change a variable without having to recode the procedure every time Instead the user moves the slider to a value and observes what happens in the model Switch Switches are a visual representation for a true false variable The user is asked to set the variable to either on true or off false by flipping the switch Chooser Choosers let the user choose a value for a global variable from a list of choices presented in a drop down menu BS Monitors display the value of any expression The expression could be a variable a complex expression or a call to a reporter Monitors automatically update several times per second plot Plots are real time graphs of data the model is generating Output The output area is a scrolling area of text which can be used to create a log of activity in the model A model may only have one output area ma Text Text boxes lets you add informative text labels to the Interface tab The contents of text boxes do not change as the model runs The 2D and 3D Views i The large black square in the Interface tab is the 2D view It s a visual representation of the NetLogo world of turtles and patches Initially it s all black because the patches are black and there are no turtles yet You can open the 3D View another visual representation of the world by clicking on the 3D button in the View Control Strip 24 gt gt IE gt 398 cit 30
95. value Reports the string that a user types into an entry field in a dialog with title value value may be of any type but is typically a string show user input What is your name user message user message value Opens a dialog with value displayed as the message value may be of any type but is typically a string user message There are count turtles turtles user one of user one of value list of choices Opens a dialog with value displayed as the message and list of choices displayed as a popup menu for the user to select from Reports the item in list of choices selected by the user value may be of any type but is typically a string 1f yes user one of Set up the model yes no setup user yes or no user yes or no value Reports true or false based on the user s response to value value may be of any type but is typically a string if user yes or no Set up the model setup Primitives Dictionary 289 NetLogo 3 1 4 User Manual V value from value from agent reporter Reports the value of the reporter for the given agent turtle or patch show value from turtle 5 who who gt 25 show value from patch 0 0 count turtles in radius 3 7 prints the number of turtles located within a 7 three patch radius of the origin values from values from agentset reporter Reports a list that contains the value of the reporter for each agent in the agen
96. way to access previous commands is with the up and down arrow keys on your keyboard Clearing To clear the large scrolling area containing previous commands and output click clear in the top right corner To clear the history popup menu choose Clear History on that menu Arranging You can hide and show the command center using the Hide Command Center and Show Command Center items on the Tools menu To resize the command center drag the bar that separates it from the model interface Or click one of the little arrows on the right end of the bar to make the command center either very big or hidden altogether To switch between a vertical command center and a horizontal one click the button with the double headed arrow just to the left of Clear 78 Interface Guide NetLogo 3 1 4 User Manual Plots To show or hide a plot s pens legend click on the word Pens in the upper right corner of a plot If you move the mouse over the white area of a plot the x and y coordinates of the mouse location will appear Note that the mouse location might not correspond exactly to any actual data points in the plot If you need to know the exact coordinates of plotted points use the Export Plot menu item and inspect the resulting file in another program When you create a plot as with all widgets the edit dialog automatically appears eno Plot Name A X axis label X min 0 0 X max 10 0 Y axis label Y min 0 0 Y
97. which lines of output Also all strings have their quotes included similar to file write Note that this command is the file i o equivalent of show and file open needs to be called before this command can be used See also file print fle type and file write file type file type value Prints value to an opened file not followed by a carriage return unlike file print and file show The lack of a carriage return allows you to print several values on the same line The calling agent is not printed before the value unlike file show Note that this command is the file i o equivalent of type and file open needs to be called before this command can be used See also file print fle show and file write file write Primitives Dictionary 217 NetLogo 3 1 4 User Manual file write value This command will output value which can be a number string list boolean or nobody to an opened file not followed by a carriage return unlike file print and file show The calling agent is not printed before the value unlike file show Its output also includes quotes around strings and is prepended with a space It will output the value in such a manner that file read will be able to interpret it Note that this command is the file i o equivalent of write and_file open needs to be called before this command can be used file open locations txt ask turtles file write xcor file write ycor See also file print fle sho
98. world command will clear the output area and set its contents to the value in imported world file It should be noted that large amounts of data being sent to the output area can increase the size of your exported worlds If you use output print output show output type output write clear output or export output in a model which does not have a separate output area then the commands apply to the output portion of the Command Center File I O In NetLogo there is a set of primitives that give you the power to interact with outside files They all begin with the prefix file There are two main modes when dealing with files reading and writing The difference is the direction of the flow of data When you are reading in information from a file data that is stored in the file flows into your model On the other hand writing allows data to flow out of your model and into a file When a NetLogo model runs as an applet within a web browser it will only be able to read data from files which are in the same directory on the server as the model file Applets cannot write to any files When working with files always begin by using the primitive ile open This specifies which file you will be interacting with None of the other primitives work unless you open a file first The next file primitive you use dictates which mode the file will be in until the file is closed reading or writing To switch modes close and then reopen the file
99. 0 write write value This command will output value which can be a number string list boolean or nobody to the Command Center not followed by a carriage return unlike_print and_show The calling agent is not printed before the value unlike_show Its output will also includes quotes around strings and is prepended with a space write hello world gt hello world See also print show and type See also output write 294 Primitives Dictionary NetLogo 3 1 4 User Manual xcor xcor k This is a built in turtle variable It holds the current x coordinate of the turtle This is a floating point number not an integer You can set this variable to change the turtle s location This variable is always greater than or equal to min pxcor 0 5 and strictly less than max pxcor 0 5 See also setxy ycor pxcor pycor xor boolean xor boolean2 Reports true if either boolean or boolean2 is true but not when both are true if pxcor gt 0 xor pycor gt 0 set pcolor blue 7 upper left and lower right quadrants turn blue Y ycor ycor This is a built in turtle variable It holds the current y coordinate of the turtle This is a floating point number not an integer You can set this variable to change the turtle s location This variable is always greater than or equal to min pycor 0 5 and strictly less than max pycor 0 5 See also_setxy xcor pxcor pycor
100. 0 50 aa 730 390 150 300 6 0 7003900 800 0 5500 500 30040 4500 2500 500 0 700 0 2008 40010 300 459800 9500 300 400500 me sob Engso ama SOM RPP 60010 9000 1050 0 6000 8500 5500 4000 somo 350 0 35040 z soon 3 4000 250 More procedures Now our turtles are eating let s make them reproduce and die too Let s also make the grass grow back We ll add all three of these of these behaviors now by making three separate procedures one for each behavior e Go to the Procedures tab e Rewrite the go procedure as follows Fo gu move turtles cal grass reproduce check death regrow grass end e Add the procedures for reproduce check death and regrow grass as shown below to reproduce ask turtles if energy gt 50 set energy energy 50 hatch 1 set energy 50 Tutorial 3 Procedures 59 NetLogo 3 1 4 User Manual end to check death ask turtles if energy lt 0 die end Lo regrow rass ask patches if random 100 lt 3 set pcolor green end Each of these procedures uses the if command Each turtle when it runs reproduce checks the value of the turile s energy variable If it is greater than 50 then the turtle runs the commands inside the first set of brackets In this case it decreases the turtle s energy by 50 then hatches a new turtle with an energy of 50 The hatch command is a NetLogo primitive which looks like this hatch
101. 2 O ON 163 SOUS A TAN 163 SOT QU IDUE DOM DOWN cccconooocancnonocnnnono nana R nr n nn nrenenanns 164 Sound EXtenSiON ci dai 165 Using the Sound Exiensionm a a A ia 165 PMI ends o lacado Nota 165 STAPTE A EE TA AA AAA A AROS 165 TAEAE PTA Ea St RS a lada ala fa eel decada lie A Na AN 165 PI EU a dt an AUT De 166 NetLogo 3 1 4 User Manual Table of Contents Sound Extension PIANOS A id 166 play note later carnada iii 166 SN A A OA 166 SLOP N0OLQ i e vetted atic loieesesendaeensl A T 167 SLOD INSTUMENT n iien ea e iia 167 SOPA a 167 SOUNA NANA A A a dd na aid 167 DU e dd o NS 167 SO tio 168 FAQ Frequently Asked QuestiONS coooccccccccocononnonccccononnnnnnnncnoncncnnnnnnnnnererrrnnnnnnnannnnr nnmnnn 171 QUESTIONS AN 171 General sl ater ROP PS dA OE E a SA Pe Sa 171 DOWN irc nai das ORE E ER 171 PADDICTS 238s at ante q PR DEU oun testa o Ud 0 ROLE a AAA RIA ty Ne 171 Usage nic dina anda 171 B h havi rS pat cia ati 172 Programa secas sonda ge dote quinas desenrola ago Cide aAA EE REEERE 172 General a sie gera Gtk pde TRA br do Da A St eA o JS AA aR OA DO dt oe 173 Why isite alled Netlog aida da de pad a 173 What programming language was NetLogo written in2 nnee 173 How do cite NetLogo in an academic publication een 173 How do cite a model from the Models Library in a publication2 173 What license is NetLogo released under Are there are any legal restrictions on
102. 2 3 4 let n 0 foreach sort patches 278 Primitives Dictionary NetLogo 3 1 4 User Manual ask set plabel n set nn 1 7 patches are labeled with numbers in left to right 7 top to bottom order sort by sort by reporter list sort by reporter agentset If the input is a list reports a new list containing the same items as the input list in a sorted order defined by the boolean true or false reporter In reporter use 21 and 22 to refer to the two objects being compared reporter should be true if 21 comes strictly before 2 in the desired sort order and false otherwise If the input is an agentset or a list of agents reports a list never an agentset of agents show sort by 1 lt 2 3 1 4 2 gt 1 2 3 4 show sort by 1 gt 2 3 1 4 2 gt 4 3 2 1 show sort by length 1 lt length 22 zzz z zz gt Pat ze zzz foreach sort by size of 1 lt size of 2 turtles ask do something 7 turtles run do something one at a time in 77 ascending order by size sprout sprout lt breeds gt sprout number commands sprout lt breeds gt number commands Creates number new turtles on the current patch The new turtles have random colors and orientations and they immediately run commands This is useful for giving the new turtles different colors headings or whatever The new turtles are created all at once then run one at a time in random order
103. 4 MOUSS INSIdO aihio eE tos asi daina tcs 244 mouSe xCcor MOUSE YCOL e eee eee e etter eee eee eae tere eee ee eae aa rnana nana a nana rranananaa 244 MOVIG CANCEL techie ee AON ee EP ee eh Ae or ede et A AN ee Lee he ee 245 MOVIE CIOS E EA a sto tats Seine Selivad da E 245 Movie grab View Movie grab interface ccccccooonononnccnccoconononononcnnnnnnncnnnnnnnnnnnnnnnnnnnnnns 245 movie set frame rat amp iii dida 245 MOVIE S AE a e A o Uk etek se od hatch a os 245 MOVIE StALUS a 246 MY lt DlCCUS Sa 246 A O 246 NAT ee 247 MiS A AA 247 A A A RIN AO aa tte rh dak A 248 DM e le ie Ud 248 NAVA OS sa DA ocio Dad 248 Neighbors Neighborsd ccocccoccccccconcnnncnnncnnncnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnneninenoss 248 lt DrEEO gt NEIGNDOMS ii AA A tits 249 E 249 falsilfo fo oa on ERR RRE RE RR RPC REI ERR PRA RE RE RR 250 NEW SCOA O det GSES A A CERA oN dl ale ORO Po ol See 250 NO AISpIay ii TO 250 alo o o o AR Ra NR RAR RAR ET RD RR ER RS 250 NO ts tes a cota tes MR EE oo stk ttt RV ad e O asa Tb Sa do do Sad o dt Poa Rc sae 251 ASUMINSUMA seitas aa tas acabo aa 251 a EN O O a dA ete 251 OL ered etter etd cere cde da Ries fee a ici a A nd a a tome ta TN E EEEE AA ok 251 NA sm pie INA E do da A e E AS A DO Sd ado a A 252 MiNoS 252 other turtles here other lt breeds gt here tretas renata 252 A A RR 253 OUI K lt DI6G0 S NGIQNDOR gt vs ss cesnataiscdsapstadsn deus
104. 61 PRA a a rai 261 PXCOM 0 COR atada airada 261 a aaa CERA e Sahat Nae ate copa O ar Men eae Mee rhea ei Maat a 262 FANdOM A EEE EARE OE tex SIE aa doa la Cana GULOSA Dada A AEE qua os 262 fANGOM 1lo abe wieik tei els ee eee bes 262 random exponential random gamma random normal random poisson 263 FANGOM int SOr TlO iaa a anda 263 random pxcor FANdOM PYCOR cccoccconcconcnonnnonnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnninnniss 264 random seca NO 264 random xcor TANQOM YCOBccccoccconcconnnonononononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnneninenss 265 e EN 265 AA sr Fea pads ane ute AE DEE N EES sa AEE EET E A 265 tema MOOT E AA a a 266 FEMOVO iia AA Mad a a Maa ea eid a ee 267 FEMOVE GUDIICATES yiii eaire e e a eE A Eeen Aana ESAE 267 REALEN A EI ENEE Re E E e TEE S EE A E 267 remove lt breed gt from remove lt breed gt to remove lt breed gt with 267 OOO RN ND RR EDER PAR DEN RR 268 FEDPIACE id Misa E RR AR RR RR ri 268 ROD OM fee it a SAN 269 resel perspeciive NN 269 COSO A A NE 269 A A 269 POD EE ass da TD RR Gane AO e te 269 06 EEE MR ONDA ORNE a E 270 ale SE pa NAAS RREO E AA DR E AR ae PAR RD 210 Odd Ea SOPRO 270 KEE i S HE EEEE A E E E EELDE e o e e a a LO 270 NetLogo 3 1 4 User Manual Table of Contents Primitives Dictionary Uli A A A E SED Sedo a arava ada ee 271 FUMES UM bes s 20c2 cere even ven eras da 271 ds A ae OB ES RA DA TE A A
105. 7 those turtles Suppose mylist is 1 2 3 4 5 6 show one of mylist 7 prints a value randomly chosen from the list See also_n of or boolean1 or boolean2 Reports true if either boolean1 or boolean2 or both is true Note that if condition1 is true then condition2 will not be run since it can t affect the result if pxcor gt 0 or pycor gt 0 set pcolor red patches turn red except in lower left quadrant other turtles here other lt breeds gt here other turtles here other lt breeds gt here Reports an agentset consisting of all turtles on the calling turtle s patch not including the caller itself If a breed is specified only turtles with the given breed are included 7 suppose I am one of 10 turtles on the same patch show count other turtles her gt 9 252 Primitives Dictionary NetLogo 3 1 4 User Manual Example using breeds breed cats cat breed dogs dog show count other dogs here 7 prints the number of dogs that are not me on my patch See also_turtles here __other end __other end Given a link and one of it s ends this reports the other end of that link First we Ask one of the ends and then ask the link In the inner block other end can be used as an idiom for the other end of the link besides the end ask ed earlier The syntax is as shown below Suppose a link L connects nodes N1 and N2 ask N1 ask L show __other end prints
106. Copyright Information 3 NetLogo 3 1 4 User Manual PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PROFITS OR BUSINESS INTERRUPTION HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY WHETHER IN CONTRACT STRICT LIABILITY OR TORT INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE Parts of NetLogo specifically the random gamma primitive are based on code from the Colt library http hoschek home cern ch hoschek colt The copyright for that code is as follows Copyright 1999 CERN European Organization for Nuclear Research Permission to use copy modify distribute and sell this software and its documentation for any purpose is hereby granted without fee provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation CERN makes no representations about the suitability of this software for any purpose It is provided as is without expressed or implied warranty NetLogo uses the MRJ Adapter library which is Copyright c 2003 Steve Roy lt sroyOroydesign net gt The library is covered by the GNU LGPL Lesser General Public License The text of that license is included in the docs folder which accompanies the NetLogo download and is also available from_http www gnu org copyleft lesser html NetLogo uses the Quaqua Look and Feel lib
107. ES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT ARE HEREBY EXCLUDED SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING MODIFYING OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE PROFIT OR DATA OR FOR DIRECT INDIRECT SPECIAL CONSEQUENTIAL INCIDENTAL OR PUNITIVE DAMAGES HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY ARISING OUT OF THE USE OF OR INABILITY TO USE SOFTWARE EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES This software is not designed or intended for use in on line control of aircraft air traffic aircraft navigation or aircraft communications or in the design construction operation or maintenance of any nuclear facility Licensee represents and warrants that it will not use or redistribute the Software for such purposes Copyright Information 5 NetLogo 3 1 4 User Manual For graphics rendering NetLogo uses JOGL a Java API for OpenGL For more information about JOGL see http jogl dev java net The library is distributed under the BSD license Copyright c 2003 Sun Microsystems Inc All Rights Reserved Redistribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met e Redistribution of source code must retain the above copyright no
108. INDOW 323 339 638 459 Command Center You should remove all the text that is in the GRAPHICS WINDOW section and then save the file So that after you are done the beginning of the file should look similar to this add model procedures her CHESHORSIO CC WINDOW 323 339 638 459 Command Center For more examples study the models and interface files in the HubNet Computer Activities section of the Models Library Disease nlogo and Disease client nlogo are good ones to start with View Updates on the Clients Currently there are two ways of sending the clients the View The first way is done automatically by NetLogo and HubNet when 2D View mirroring is enabled and the client has a View in the interface Whenever a patch or turtle is redrawn in the NetLogo View it will be redrawn on all the clients Actually updates are accumulated and sent out periodically about five times a second This means that a lot of messages can be sent to the clients if a lot of turtles or patches are being redrawn It is possible to reduce the number of messages sent to the clients and thus possibly speed up the model by making the View in the model not update This can be done using the no display and display primitives or by toggling the display on off switch in the View Control Strip A second way of sending the clients the View is to use the hubnet broadcast view and hubnet send view primitives hubnet broadcast view and hubnet send
109. If no link exists then it reports nobody to find friendship with ca ect 2 ask turtle 0 create link to turtle 1 create link from turtle 1 show __in link from turtle 1 prints turtle 3 show __out link to turtle 1 prints turtle 2 show __link with turtle 1 prints turtle 2 end This reporter is part of the experimental Links support in NetLogo See the_Links section of the Programming Guide for more details 254 Primitives Dictionary NetLogo 3 1 4 User Manual output print output show output type output write output print value output show value output type value output write value These commands are the same as the print show type and write commands except that value is printed in the model s output area instead of in the Command Center If the model does not have a separate output area then the Command Center is used P patch patch pxcor pycor Given two integers reports the single patch with the given pxcor and pycor The coordinates are the actual coordinates they are not computed relative to the calling agent as with patch at pxcor and pycor must be integers ask patch 3 4 set pcolor green 7 patch with pxcor of 3 and pycor of 4 turns green See also patch at patch ahead patch ahead distance Reports the single patch that is the given distance ahead of the calling turtle that is along the turtle s current heading Reports nobody if the patch d
110. If the sprout lt breeds gt form is used the new turtles are created as members of the given breed sprout 1 set color red sprout sheep 1 set color black Note While the commands are running no other agents are allowed to run any code as with the without interruption command This ensures that the new turtles cannot interact with any other agents until they are fully initialized In addition no display updates take place until the commands are done This ensures that the new turtles are never drawn in the view until they are fully initialized Primitives Dictionary 279 NetLogo 3 1 4 User Manual sqrt sqrt number Reports the square root of number stamp stamp The calling turtle leaves an image of its shape in the drawing at its current location Note The shapes made by stamp may not be pixel for pixel identical from computer to computer stamp erase stamp erase The calling turtle removes any pixels below it in the drawing inside the bounds of its shape Note The shapes made by stamp erase may not be pixel for pixel identical from computer to computer standard deviation standard deviation list Reports the unbiased statistical standard deviation of a list of numbers Ignores other types of items show standard deviation 1 2 3 4 5 6 gt 1 8708286933869707 show standard deviation values from turtles energy 7 prints the standard deviation of the variable energy from all the turtles start
111. Information Plots and Monitors A purpose to modeling is to gather data on a subject or topic that would be very difficult to do in a laboratory situation NetLogo has two main ways of displaying data to the user plots and monitors Plots The plot in Wolf Sheep Predation contains three lines sheep wolves and grass 4 The grass count is divided by four so it doesn t make the plot too tall The lines show what s happening in the model over time To see which line is which click on Pens in the upper right corner of the plot window to open the plot pens legend A key appears that indicates what each line is plotting In this case it s the population counts When a plot gets close to becoming filled up the horizontal axis increases in size and all of the data from before gets squeezed into a smaller space In this way more room is made for the plot to grow If you want to save the data from a plot to view or analyze it in another program you can use the Export Plot item on the File menu It saves this information to your computer in a format that can by read back by spreadsheet and database programs such as Excel You can also export a plot by control clicking Mac or right clicking Windows it and choosing Export from the popup menu Monitors Monitors are another method of displaying information in a model Here are the monitors in Wolf Sheep Predation time ticks sheep wolves grass 4 0 0 0 0 The monitor l
112. Interface A dialog box will appear e In the dialog box type count turtles see image below e Press the OK button to close the dialog box Tutorial 3 Procedures 55 count turtles 100 NetLogo 3 1 4 User Manual a nos am gt 2 so ne Monitor Reporter kount turtles Display name Decimal places 3 turtles is an agentset the set of all turtles count tells us how many agents are in that set Let s make the second monitor now e Create a monitor using the monitor icon on the Toolbar and click on an open spot in the Interface A dialog box will appear e Inthe Reporter section of the dialog box type count patches with pcolor green see image below e In the Display name section of the dialog box type green patches e Press the OK button to close the dialog box setup count turtles 100 green patches 1225 OS gt 1104 it 30 90 Monitor Reporter count patches with pcolor green Display name green patches Decimal places 3 Here we re using count again to see how many agents are in an agentset patches is the set of all the patches but we don t just want to know how many patches there are total we want to know how many of them are green That s what with does it makes a smaller agentset of just those 56 Tutorial 43 Procedures NetLogo 3 1 4 User Manual agents for whom the condition in the brackets is true The conditi
113. Issues If NetLogo malfunctions please send us a bug report See the Contact Us section for instructions Known bugs all systems e Integers in NetLogo must lie in the range 2147483648 to 2147483647 if you exceed this range instead of a runtime error occurring you get incorrect results e Out of memory conditions are not handled gracefully e The stop and report commands do not work properly if used inside without interruption we are already working on fixing this e The uphill and downhill reporters sometimes return incorrect answers for turtles which are standing on patch boundaries we are already working on fixing this but in the meantime you may wish to use uphi114 and downhi114 instead e If you use Export World to suspend a model run and then resume it later with Import World this may change the outcome of the model run if your model involves turtles dying and new turtles being born because the export import may change what who numbers get assigned to new turtles we are already working on fixing this e Export World does not include the contents of plots we are already working on fixing this e Extensions that require additional external jars don t work from models saved as applets we are already working on fixing this e The 3D View doesn t work on some graphics configurations on others the 3D View works but 3D full screen mode doesn t e A bug in Java causes patch colors imported using import pcolors to be brighter t
114. Known Issues 17 NetLogo 3 1 4 User Manual e On versions of Mac OS X prior to 10 4 it is possible for NetLogo s menus to get confused so that the Quit item does not work If this happens you can quit NetLogo by pressing the red close button on the left end of the NetLogo s title bar e On Mac OS X 10 2 only the User Manual item on the Help menu will sometimes launch a web browser other than your default browser e On Mac OS X 10 2 only opening the Models Library can trigger an error if you have malformed fonts installed If this happens you should determine which fonts in System Library Fonts and other font directories are causing the problem and remove them Linux UNIX only bugs e User Manual always opens in Mozilla not your default browser One possible workaround is to bookmark the file docs index html in your favorite browser Another workaround is to make a symlink that s called mozilla that s the command name NetLogo tries to run but actually runs a different browser e We have discovered a problem on Linux where the exp reporter sometimes returns a slightly different answer differing only in the last decimal place for the same input According to an engineer at Sun this should only happen on Linux kernel versions 2 4 19 and earlier but we have observed the problem on more recent kernel versions We assume the problem is Linux specific and does not happen on other Unix based systems We are not sure if the problem ever o
115. Logo can now make sounds and music this is done with a new experimental sound extension that is also an example of how to use the extensions API e new controlling API lets users control NetLogo from external Java code such as for automating multiple runs Version 2 0 December 2003 e full support for Mac OS X improved Linux support e minimum Java version is now 1 4 1 Windows 95 MacOS 8 MacOS 9 no longer supported e increased overall reliability e improved look and feel throughout the application e faster and more flexible graphics labels turtle sizes exact turtle positions all now fast reliable and flicker free e suite of primitives for reading and writing external files e strict math mode now always on for reproducible results e export graphics window or interface tab as image file e revamped BehaviorSpace various improvements made some old features are missing e Mersenne Twister random number generator e many new primitives e computer HubNet improved reliability no longer alpha or beta improved graphics window mirroring features and performance Version 1 3 June 2003 e graphics window control strip e choosers e strict math mode so results are identical on all platforms requires Java 1 3 or higher e new primitives including run runresult and map foreach filter reduce e some primitives now accept a variable number of inputs What s New 11 NetLogo 3 1 4 User Manual Version 1 2 March 2003 e alpha
116. M Xmx512M lt string gt Note that at least as of Mac OS X 10 3 the maximum possible heap size for any Java program is two gigabytes e Other Java VMs from Sun let you set the ceiling on the command line as follows If you are using a VM from a different vendor the method may be different Note that we recommend the server flag for best performance in most situations We also recommend setting the noddraw option to true when using the GUI as Direct Draw can conflict with OpenGL java server Dsun java2d noddraw true Xms16M Xmx512M jar NetLogo jar Can I import GIS data into NetLogo Yes a number of users have constructed models using raster GIS data We don t know of users who have used vector GIS data other than by converting it to raster data first One simple way is to use import pcolors but that only works for importing maps that are images not maps in other formats We do not have built in support for reading common GIS formats However a number of our users are working with GIS data successfully using NetLogo code that reads GIS data using our file I O primitives such as file open It is also possible to use external software to convert GIS data into a format that is easier to read from NetLogo than the original format This has been discussed on the NetLogo Users Group several times We encourage users interested in using NetLogo for GIS applications to share their questions and experiences with the group My model
117. N2 ask N2 ask L show __other end prints N1 This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details __ out lt breed gt neighbor __out lt breed gt neighbor agent Reports true if there is a link going from the caller to agent to check friendship neighbors ca cct turtles 2 ask turtle 0 create link to turtle 1 show __in link neighbor turtle 1 j prints false show __out link neighbor turtle 1 prints true Primitives Dictionary 253 NetLogo 3 1 4 User Manual ask turtle 1 show __in link neighbor turtle 0 prints true show __out link neighbor turtle 0 prints false end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details out lt breed gt neighbors out lt breed gt neighbors Reporis the agentset of all the node turtles that have links coming from the caller to them breed links link breed for network links to become friendly node procedure create links to friends show _ out link neighbors prints the agentset of friends end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details __out lt breed gt to __out lt breed gt to agent Reports the link turtle from the call to the agent
118. Nylon String Guitar 26 Steel Acoustic Guitar 27 Jazz Electric Guitar 28 Clean Electric Guitar 29 Muted Electric Guitar 30 Overdriven Guitar 31 Distortion Guitar 32 Guitar harmonics Bass 33 Acoustic Bass 34 Fingered Electric Bass 35 Picked Electric Bass 36 Fretless Bass 37 Slap Bass 1 38 Slap Bass 2 39 Synth Bass 1 40 Synth Bass 2 Strings Violin Viola Cello Contrabass Tremolo Strings Pizzicato Strings Orchestral Harp Timpani BK Bp DBD ds ds BBA 0 II NA UNA 168 NetLogo 3 1 4 User Manual Reed 65 Soprano Sax 66 Alto Sax 67 Tenor Sax 68 Baritone Sax 69 Oboe 70 English Horn 71 Bassoon 72 Clarinet Pipe 73 Piccolo 74 Flute 75 Recorder 76 Pan Flute 77 Blown Bottle 78 Shakuhachi 79 Whistle 80 Ocarina Synth Lead 81 Square Wave 82 Sawtooth Wave 83 Calliope 84 Chiff 85 Charang 86 Voice 87 Fifths 88 Bass and Lead Synth Pad 89 New Age 90 Warm 91 Polysynth 92 Choir 93 Bowed 94 Metal 95 Halo 96 Sweep Synth Effects 97 Rain 98 Soundtrack 99 Crystal 100 Atmosphere 101 Brightness 102 Goblins 103 Echoes 104 Sci fi Ethnic 105 Sitar 106 Banjo 107 Shamisen 108 Koto 109 Kalimba 110 Bag pipe 111 Fiddle 112 Shanai Sound Extension NetLogo 3 1 4 User Manual Ensemble Percussive 49 String Ensemble 1 113 Tinkle Bell 50 String Ensemble 2 114 Agogo 51 Sy
119. OS NR RR OS E SNS NS ae 290 Wall bid ando A cafe don aa De Ga a dq contas octets ute dt OR 290 VALES ese cena dao Coto UA ans de eA e TEE lo to A as SA A O NA pi cel 291 A O 291 Will a A mR E CAD 291 WIDE A A iii cs 291 A 292 lt DreCA S WIL tosse a a a a nasa laa Mid 292 O 292 WI darti 293 WIthoUt INterruptiQN ccocccccccncconnnonononnnonnnononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnnineniss 293 LOLO NN RN 293 world width world height oocccccccccccncccnnccnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnnnss 294 WIap COlO vato aa RR RR RR RR 294 MO scat rd ceia cast La a e ND RR RU a e O nes 294 DX sort ated a al a GL et a de otha DER hat 295 a EI SOS RR ond tn are Dd 295 OA 295 A A E A E A ONES AA 295 A TT 295 SR E a A CS GA SA UD PARE FS PRS SRT ns OEE AR SEPP SP ae 295 RT 295 XV NetLogo 3 1 4 User Manual xvi What is NetLogo NetLogo is a programmable modeling environment for simulating natural and social phenomena It was authored by Uri Wilensky in 1999 and is in continuous development at the Center for Connected Learning and Computer Based Modeling NetLogo is particularly well suited for modeling complex systems developing over time Modelers can give instructions to hundreds or thousands of independent agents all operating concurrently This makes it possible to explore the connection between the micro level behavior of individuals and the macro level patterns that emerge from
120. Programming Guide NetLogo 3 1 4 User Manual A turtle s breed agentset is stored in the breed turtle variable So you can test a turile s breed like this if breed wolves Note also that turtles can change breeds A wolf doesn t have to remain a wolf its whole life Let s change a random wolf into a sheep ask one of wolves set breed sheep The set default shape primitive is useful for associating certain turtle shapes with certain breeds See the section on shapes below Here is a quick example of using breeds breed mice mouse breed frogs frog mice own cheese to setup ca create custom mice 50 set color white set cheese random 10 create custom frogs 50 set color green end Code Example Breeds and Shapes Example Buttons Buttons in the interface tab provide an easy way to control the model Typically a model will have at least a setup button to set up the initial state of the world and a go button to make the model run continuously Some models will have additional buttons that perform other actions A button contains some NetLogo code That code is run when you press the button A button may be either a once button or a forever button You can control this by editing the button and checking or unchecking the Forever checkbox Once buttons run their code once then stop and pop back up Forever buttons keep running their code over and over again until either the c
121. S iiuuiniiiioicaniarnarnaiadaaaai 27 Sample Model Wolf Sheep Predati0N ccccccooooooccccccnononnnononcnnnnnnncnnnnnnnnnnnnnncccnnnnnnnnnnnnnnnnns 27 Controlling the Model Button Ss 0 ii aa 28 Adjusting Settings Sliders and SWitCheS ccoccnnnnononcccnononcccnnnnanonnnnnccccnnnnnnonnnncnnnnnnnnnnnnnnnns 29 Gathering Information Plots and MONItOFS ccccconnononcconnnonccnnnnanononononcnnnnannonnnnnnnnnnnnnnnnnnnnns 31 BIOIS aS P secta cid eLo E e A A Cr een sae SCN OL ad RR dA ee 31 AVC 6 Co IE EAEE A E E E en oe 31 Controlling the MEW di A A 31 The Models Libra Votos al Adra anda 35 STel EALO E EAE A E IS A a 36 Gurrictilar Mod EE RR IR ad Da 36 Code Example 36 HubNet Calculator amp Computer ActIV tIOS ccooooooocccnncccconnnononncnnccnnnnnnnnnnnnnnnnnnnnnnnnnnnnos 36 Whats Next vaso q o a EE UU a ae DE a A A A A 36 Tutorial 2 COMMANQS occccoconancccnnnnnncononanacononanarononananr conan rcona nana rnna nana coronan rr nnnn nnmnnn nannan nnana 37 sample Model Trafiic Basic rad S a 37 The Command Center saidas ee ceveidecnecenigadesedtiessnddecenileccauacessueudcdudesseddeswaceena easededguanicecess 37 Working WEGA OS e 40 Agent Monitors and Agent COMMANETS ccccccceccsssseeeeeeeeeessseeseeeeeeeeeeessesneeeeeeeeeesssssaaes 42 Whats Next a ac cias 45 Tutorial 3 Procedures cinco 47 Agents ANA POCO Ut sis avi dad eid ial Meine eds 47 Making the setup DU LON cocccccnconnconnnonncnnon
122. String argv HeadlessWorkspace workspace new HeadlessWorkspace try workspace open models Sample Models Earth Science Fire nlogo workspace command set density 62 workspace command random seed 0 workspace command setup workspace command repeat 50 go System out println workspace report burned trees workspace dispose 156 Controlling Guide NetLogo 3 1 4 User Manual catch Exception ex ex printStackTrace In order to compile and run this either Net Logo jar or NetLogoLite jar from the NetLogo distribution must be in your classpath The latter jar is smaller but is only capable of headless operation not full GUI operation When running in a context that does not support a graphical display the system property java awt headless must be true to force Java to run in headless mode HeadlessWorkspace automatically sets this property for you Since there is no GUI NetLogo primitives which send output to the command center or output area now go to standard output instead export world can still be used to save the model s state export view works for writing an image file with a snapshot of the otherwise invisible 2D view The report method is useful for getting results out of the model and into your Java code You can make multiple instances of HeadlessWorkspace and they will operate independently on separate threads without interfering with each other
123. This brings up a dialog where you can select one or more shapes and bring them into your model Select the shapes then press the Import button Similarly you can use the Import from model button to borrow shapes from another model Default shapes Here are the shapes that are included by default in every new NetLogo model N NOS vor Soe At 01 ELXOSA A EOX First row default airplane arrow box bug butterfly car Second row circle circle 2 cow face happy face neutral face sad fish Third row flag flower house leaf line pentagon person Fourth row plant square square 2 star target tree triangle Fifth row triangle 2 truck turtle wheel x Shapes Editor Guide 123 NetLogo 3 1 4 User Manual Shapes library And here are the shapes in the shapes library including all of the default shapes too Creating and Editing Shapes Pressing the New button will make a new shape Or you may select an existing shape and press Edit 124 Shapes Editor Guide NetLogo 3 1 4 User Manual Tools In the upper left corner of the editing window is a group of drawing tools The arrow is the selection tool which selects an already drawn element To draw a new element use one of the other seven tools e The line tool draws line segments e The circle square and polygon tools come in two versions solid and outline When using the polygon tool click the mouse to add a new segment to the polygon Whe
124. Use set plot x range to control the range of values to be histogrammed and set the pen interval either directly with set plot pen interval or indirectly via set histogram num bars to control how many bars that range is split up into Be sure that if you want the histogram drawn with bars that the current pen is in bar mode mode 1 As of NetLogo 2 0 2 for histogramming purposes the plot s X range is not considered to include the maximum X value Values equal to the maximum X will fall outside of the histogram s range histogram from turtles color 5 draws a histogram showing how many turtles there are 77 of each color Note using this primitive amounts to the same thing as writing histogram list values from agentset reporter but is more efficient histogram list histogram list list Histograms the values in the given list after first removing any previous points drawn by the current plot pen 222 Primitives Dictionary NetLogo 3 1 4 User Manual See histogram from above for more information home home k The calling turtles moves to the origin 0 0 Equivalent to setxy 0 0 hsb hsb hue saturation brightness Reports a number in the range 0 to 140 not including 140 itself that represents the given color specified in the HSB spectrum in NetLogo s color space All three values should be in the range 0 0 to 1 0 The color reported may be only an approximation since the NetLogo color space does not incl
125. Useful if you have multiple link breeds in one model Even if the network does contain cycles and is not a true tree structure this layout will still work although the results will not always be pretty If agentset is an agentset of patches an error is thrown breed links link to make a tree set default shape turtles circle set 6 Il ask turtle 0 create link with turtle 1 create link with turtle 2 create link with turtle 3 ask turtle 1 create link with turtle 4 create link with turtle 5 do a radial tree layout centered on turtle 0 __layout radial turtles turtle 0 links end This command is part of the experimental Links support in NetLogo See the_Links section of the Programming Guide for more details __layout spring __layout spring agentset spring constant spring length repulsion constant Arranges the agentset of turtles agentset as if the links with which they are connected to each other were springs and the nodes were repelling each other spring constant is a measure of the tautness of the spring It is the resistance to change in their length spring constant is the force the spring would exert if it s length were changed by 1 unit spring length is the zero force length or the natural length of the springs This is the length which all springs try to achieve either by pushing out their nodes or pulling them in repulsion constant is a
126. a HubNet activity we refer to it as a HubNet server Participants use a client application to log in and interact with the HubNet server There are two types of HubNet available With Computer HubNet participants run the HubNet Client application on computers connected by a regular computer network In_Calculator HubNet created in conjunction with Texas Instruments participants use Tl 83 graphing calculators as clients which communicate via the Tl Navigator system We hope to add support for other types of clients such as cell phones and PDA s Personal Digital Assistants HubNet Guide 135 NetLogo 3 1 4 User Manual Computer HubNet Activities The following activities are available in the Models Library in the Computer HubNet Activities folder For many models you will find a discussion of its educational goals and suggested ways to incorporate it into your classroom in the Participatory Simulations Guide on the Participatory Simulations Project web site More information can also be found in the Information Tab in each model e Disease A disease spreads through the simulated population of students e Gridlock Students use traffic lights to control the flow of traffic through a city e Polling Ask students questions and plot their answers e Tragedy of the Commons Students work as farmers sharing a common resource Requirements To use Computer HubNet you need a networked computer with NetLogo installe
127. aE ANCE ER A A 271 SCalG COlO asst tess sae eh areca ads 271 Sl ni Pe ag eee crete eae 272 EMSCMICOLON E sema dia EA ET CRIADA DO GRE NE Da RO laa 212 SENENCe SC sesta A ido Sate cao a aca 212 SOL sinos dio SENSO DAL ii o GS ra DD E SRS SO EE TU Da fa RAR NR 273 SEt CUTeN OIC Visio 273 Set c rrentplot e a A AR A Ri dais 274 Set CUrrentplO 01 1 ee 274 SOt dbfault SNaAPS issiecushcraceiessevelavheneetavente DANE Gde a 274 Set histograM NUM DalS arine ccoo n nn nono nnnnnn nn nn a a a aeie 275 Sel line ihicknesS ss ses ll dt lt ts 275 SEt PlOt D OM COON eee cece E cee nono non ron rro nro rro rro rnn nn nn nn nn nn nn nn T 275 set plot pen intelIVal eere a e crono ron non rro nro rro EE nn nn nn nn nn nn aat 275 Set plOt HeENn MOd iia 275 set plot x range Set plOl Y ANQl ooocooccconoocooononononononnno nono nononononnnnnnnnnnnnnnnnnnnnonnnonnnnnnos 276 AA A AAE EAE E O 276 E mO EAE A O AA 276 PENA a trae 277 shape Se A A A 277 A A Da Cai alas ates 277 show turle St n 277 SUS a A AAA AAA ed a 278 MAA a aa 278 ZA A A DO a A E ae 278 NN NN 278 A NA 279 Sprout SPrOUt lt DIBedOS gt occocccccccnnccnnccnncnnnccnncnnn cnn nr rn rre 279 SOM oi OR 280 STAMP ON 280 SIMPSON E S 280 siandard deVIaION ea nann eine ai 280 STANMUD TN ee 280 SLOP 2 sm E sh ta teieein cada duni alado de dass nigh ages die hater Pad a eles gadis ee 281 SUD Oia AAA A ao 281 SUDIISE SUSTO A A ie hie en ee ee el 281 SUDIFACIZORANINQS cccccccconc
128. abeled time ticks tells us how much time has passed in the model The other monitors show us the population of sheep and wolves and the amount of grass Remember the amount of grass is divided by four to keep the plot from getting too tall The numbers displayed in the monitors update continuously as the model runs whereas the plots show you data from the whole course of the model run Note that NetLogo has also another kind of monitor called agent monitors These will be introduced in Tutorial 2 Controlling the View If you look at the view you ll see a strip of controls along the top edge The control strip lets you control various aspects of the view Tutorial 1 Models 31 NetLogo 3 1 4 User Manual Let s experiment with the effect of these controls e Press setup and then go to start the model running e As the model runs move the slider in the control strip back and forth What happens This slider is helpful if a model is running too fast for you to see what s going on in detail e Move the speed slider all the way to the right again e Now try pressing and unpressing the red arrowhead in the control strip e Also try pressing and unpressing the on off switch in the control strip What happens The shapes button and the freeze button are useful if you re impatient and want a model to run faster When shapes are turned off turtles are drawn as solid squares it takes less work for NetLogo to dra
129. ake agentsets 7 all red turtles turtles with color red all red turtles on my patch turtles here with color red 7 patches on right side of view patches with pxcor gt 0 all turtles less than 3 patches away turtles in radius 3 the four patches to the east north west and south patches at points 1 0 0 1 1 0 O 1 Shorthand for those four patches neighbors4 7 turtles in the first quadrant that are on a green patch turtles with xcor gt 0 and ycor gt 0 and pcolor green 5 turtles standing on my neighboring four patches turtles on neighbors4 Once you have created an agentset here are some simple things you can do e Use ask to make the agents in the agentset do something e Use any to see if the agentset is empty e Use count to find out exactly how many agents are in the set And here are some more complex things you can do e Pick a random agent from the set using one of For example we can make a randomly chosen turtle turn green set color of one of turtles green Or tell a randomly chosen patch to sprout a new turtle ask one of patches sprout 1 e Use the max one of Or min one of reporters to find out which agent is the most or least along some scale For example to remove the richest turtle you could say ask max one of turtles sum assets die e Make a histogram of the agentset using the histogram f rom command e Use values from to make a list
130. ame gnutar You can find out if you are already using the GNU version by typing tar version and seeing if the output says tar GNU tar Applets 176 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual tried to run one of the applets on your site but it didn t work What should do Current versions of NetLogo require that your web browser support Java 1 4 1 or higher Here s how to get the right Java e If you re on Windows 98 or newer you need to download the Java browser plugin from http www java com en download windows manual jsp e If you re on Mac OS X you need OS X 10 2 6 or higher If you re on OS X 10 2 you also need Java 1 4 1 Update 1 which is available through Software Update OS X 10 3 already has the right Java You must also use a web browser that supports Java 1 4 Internet Explorer does not work Safari does e If you re on Windows 95 MacOS 8 or MacOS 9 running models over the web is no longer supported you must download the NetLogo 1 3 1 application and run the models that way instead e If you re on Linux or another Unix you will need version 1 4 1 or higher of the Sun Java Runtime Environment It is available for download at_http www java com Check your browser s home page for information about installing the Java plugin If you think you have the right browser and plugin but it still doesn t work check your browser s preferences to make sure that Java is enabled Can make my mod
131. ame of a NetLogo extension For example extensions sound jar NetLogo will look for extensions in two places the directory that holds the model and the NetLogo extensions folder So to install a NetLogo extension for use by any model put the extension file for example sound jar in the extensions directory inside the NetLogo directory Or you can just keep the extension in the same folder as the model that uses it You can also use extensions that are not installed in your NetLogo extensions folder by providing a path relative to the directory that contains the model or an absolute path __ extensions lib sound jar 7 relative path _ extensions jars sound jar relative path extensions c myfiles sound jar absolute Windows path extensions Users me sound jar absolute Mac Unix path You may also use an extension which is stored on an Internet server instead of your local computer Extensions Guide 149 NetLogo 3 1 4 User Manual Just use the URL where you have stored the extension For example __ extensions http yourdomain net jars sound jar Using __extensions tells NetLogo to find and open the specified extension and makes the custom commands and reporters found in the extension available to the current model You can use these commands and reporters just as if they were built in NetLogo primitives To use more than one extension list each extension separately For exa
132. and retrieve NetLogo constants such as numbers lists booleans and strings file write will always output the variable in such a manner that file read will be able to interpret it correctly file open myfile txt Opening file for writing ask turtles file write xcor file write ycor file close file open myfile txt Opening file for reading ask turtles setxy file read file read file close Code Examples File Input Example and File Output Example Letting the user choose The user directory user file and user new file primitives are useful when you want the user to choose a file or directory for your code to operate on Movies This section describes how to capture a QuickTime movie of a NetLogo model Programming Guide 111 NetLogo 3 1 4 User Manual First use the movie start command to start a new movie The filename you provide should end with mov the extension for QuickTime movies To add a frame to your movie use either movie grab view Of movie grab interface depending on whether you want the movie to show just the current view or the entire Interface tab In a single movie you must use only one movie grab primitive or the other you can t mix them When you re done adding frames use movie close 7 export a 30 frame movie of the view setup movie start out mov movie grab view show the initial state repeat 30 go movie grab view movie close By default a movie will p
133. andom Numbers e Turtle Shapes e Plotting e Strings e Output e File I O e Movies e Perspective e Drawing e Topology e Links e Tie Agents The NetLogo world is made up of agents Agents are beings that can follow instructions Each agent can carry out its own activity all simultaneously In NetLogo there are three types of agents turtles patches and the observer Turtles are agents that move around in the world The world is two dimensional and is divided up into a grid of patches Each patch is a square piece of ground over which turtles can move The observer doesn t have a location you can imagine it as looking out over the world of turtles and patches When NetLogo starts up there are no turtles yet The observer can make new turtles Patches can make new turtles too Patches can t move but otherwise they re just as alive as turtles and the observer are Patches have coordinates The patch at coordinates 0 0 is called the origin and the coordinates of the other patches are the horizontal and vertical distances from this one We call the patch s coordinates pxcor and pycor Just like in the standard mathematical coordinate plane pxcor increases as you move to the right and pycor increases as you move up Programming Guide 85 NetLogo 3 1 4 User Manual The total number of patches is determined by the settings min pxcor max pxcor min pycor and max pycor When NetLogo starts up min pxcor max p
134. ands you type here are only done by this particular turtle e In the Agent Commander of the Turtle Monitor for turtle O type set color pink What happens in the View Did anything change in the Turtle Monitor A second way to change one turtle s color is to go directly to the color variable in the Turtle Monitor and change the value e Select the text to the right of color in the Turtle Monitor e Type in a new color such as green 2 What happened The third way to change an individual turtle s or patch s color is to use the observer Since the observer oversees the NetLogo world it can give commands that affect individual turtles as well as groups of turtles e In the Command Center select observer from the popup menu or use the tab key e Type ask turtle 0 set color blue and press return What happens Just as there are Turtle Monitors there are also Patch Monitors Patch monitors work very similarly to Turtle Monitors Can you make a patch monitor and use it to change the color of a single patch 44 Tutorial 2 Commands NetLogo 3 1 4 User Manual If you try to have the observer ask patch 0 set pcolor blue you ll get an error message Command Center A Clear ERROR Expected a number here rather than a list or block patches gt ask patch O set pcolor blue Jr To ask an individual turtle to do something we use its who number But patches don t have who numbers
135. appens to them when they reach the edge of the world There are a few common options the turtle is reflected back into the world either systematically or randomly the turtle exits the system dies or the turtle is hidden It is no longer necessary to check the bounds using turtle coordinates instead we can just ask NetLogo if a turtle is at the edge of the world There are a couple ways of doing this the simplest is to use the can move primitive if not can move distance rt 180 can move merely returns true if the position distance in front of the turtle is inside the NetLogo world false otherwise In this case if the turtle is at the edge of the world it simple goes back the way it came You can also use patch ahead 1 nobody in place of can move If you need to do something smarter that simply turning around it may be useful to use patch at with dx and dy Programming Guide 117 NetLogo 3 1 4 User Manual if patch at dx 0 nobody set heading heading if patch at O dy nobody set heading 180 heading This tests whether the turtle is hitting a horizontal or vertical wall and bounces off that wall In some models if a turtle can t move forward it simply dies exits the system like in Conductor or Mousetraps if not can move distance die If you are moving turtles using setxy rather than forward you should test to make sure the patch you are about to move to exists since setxy throws a runtime
136. aries canary breed snakes snake to setup ca create custom canaries 50 set color yellow create custom snakes 50 set color green end Note While the commands are running no other agents are allowed to run any code as with the without interruption command This ensures that the new turtles cannot interact with any other agents until they are fully initialized In addition no display updates take place until the commands are done This ensures that the new turtles are never drawn in the view until they are fully initialized create tem porary plot pen create temporary plot pen string A new temporary plot pen with the given name is created in the current plot and set to be the current pen Few models will want to use this primitive because all temporary pens disappear when clear plot or clear all plots are called The normal way to make a pen is to make a permanent pen in the plot s Edit dialog If a temporary pen with that name already exists in the current plot no new pen is created and the existing pen is set to the the current pen If a permanent pen with that name already exists in the current plot you get a runtime error The new temporary plot pen has the following initial settings e Pen down e Color black e Mode O line mode Primitives Dictionary 205 NetLogo 3 1 4 User Manual e Interval 1 0 See clear plot clear all plots and set current plot pen D date and time date and time Rep
137. ary plot pen eee ease ease een eeaa ease eeaaeeaneeaareraeeaos 205 Dl od ato E do A 206 daie and timies ta AS ae eae Wise tae 206 1e 1 E SEEE re aor ee A UE ERR DES PRENDE NERO E TEN EA NN 206 A A DE TDR GO ORE ON NBR DR REU ERR RED 206 fo TMA Lok OA a iii 207 Ad ii AA AAA eins 207 CISTAN CO da 208 USA COX Si 208 A A RN EN So 208 GOW AMINA Bsc iced strc an A A A A tinta 209 AN 209 E a A ad a E Rie hela sae no 209 MODA SS a 209 JLo PORRA OP OD ROS RE NUDE SPD ODE SEO SENDER DS DOR See SANS PRA ENE RE 209 nto o cece ness NR DIC PANE PO le ERRA AR PU PN 210 ENG dadas alada SA dA ONAN EEEE do a o ETA Ee 210 eiror MesSaADE atinente almada lada ti a 210 Alis AA ia eee adnate deta 211 ES E O DU NAT 211 export view export interface export output export plot export all plots NetLogo 3 1 4 User Manual Table of Contents Primitives Dictionary OXDOM WOMG nad A ias 211 EXTENSA ta tube steed 212 AAC Nessa feats ASEE E Souda aaa S AEE sbinndidwans A A N 213 O 213 TACO ad a E a E 213 AC a 213 TIA A A SC ae 214 IRA O ON 214 lO clOsO lia A A a tia 214 Tile delete at siri ie raio ed tiles add een de vat uae tanta E a at a en o 214 TIIB CXISTS 2 A A A A 215 EEO 6 e PR CORRER MENERA OMG an 215 MESA A AS 215 ERE T O cliches Nei aes ciel Net au Da a i yee Nt De tate ale bettie Set hii ds Wie Dao 216 fil read cha ractetS iinei a iaa Sad didi deh Sok o ae data LAGO nd saucdebdedegieadedanieee 216 ferea gt
138. at this turtle monitor we can see all of the variables that belong to the red car A variable is a place that holds a value that can be changed Remember when it was mentioned that all colors are represented in the computer as numbers The same is true for the agents For example turtles have an ID number we call their who number Let s take a closer look at the turtle monitor What is this turtle s who number What color is this turtle What shape is this turtle This turtle monitor is showing a turtle who that has a who number of 0 a color of 15 red see above chart and the shape of a car There are two other ways to open a turtle monitor besides right clicking or control clicking depending on your operating system One way is to choose Turtle Monitor from the Tools menu then type the who number of the turtle you want to inspect into the who field and press return The Tutorial 2 Commands 43 NetLogo 3 1 4 User Manual other way is to type inspect turtle 0 or other who number into the Command Center You close a turtle monitor by clicking the close box in the upper left hand corner Macintosh or upper right hand corner other operating systems Now that we know more about Agent Monitors we have three ways to change an individual turtle s color One way is to use the box called an Agent Commander found at the bottom of an Agent Monitor You type commands here just like in the Command Center but the comm
139. ata is stored in memory until the experiment is done very large experiments could run out of memory And if anything interrupts the experiment such as a runtime error running out of memory or a crash or power outage no results will be written For long experiments you may want to use both spreadsheet and table formats so that if something happens you ll at least get a table of partial results After selecting your output formats BehaviorSpace will prompt you for the name of a file to save the results to The default name ends in csv You can change it to any name you want but don t leave off the csv part that indicates the file is a Comma Separated Values CSV file This is a plain text data format that is readable by any text editor as well as by most popular spreadsheet and database programs A dialog will appear titled Running Experiment In this dialog you ll see a progress report of how many runs have been completed so far and how much time has passed If you entered any reporters for measuring the runs and if you left the Measure runs at every tick box checked then you ll see a plot of how they vary over the course of each run You can also watch the runs in the main NetLogo window If the Running Experiment dialog is in the way just move it to a different place on the screen The view and plots will update as the model runs If you don t need to see them update then use the checkboxes in the Running Experiment dial
140. atch agentset Primitives Dictionary 231 NetLogo 3 1 4 User Manual is string is turtle is turtle agentset is agent value is agentset value is boolean value is lt breed gt value __is link value is list value is number value is patch value is patch agentset value is string value is turtle value is turtle agentset value Reports true if value is of the given type false otherwise item item index list item index string On lists reports the value of the item in the given list with the given index On strings reports the character in the given string at the given index Note that the indices begin from 0 not 1 The first item is item 0 the second item is item 1 and so on suppose mylist is 2 4 6 8 10 show item 2 mylist gt 6 show item 3 my shoe gt g The __is link reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details J jump jump number Turtles move forward by number units all at once without the number of turns it takes depending on the distance 232 Primitives Dictionary NetLogo 3 1 4 User Manual This command is useful for synchronizing turtle movements A turtle takes 15 turns to do fd 15 but only one turn to do jump 15 If the turtle cannot jump number units because it is not permitted by the current topology the turtle does not move at all Note When turtles jump they do not
141. ation see_Varying Numbers of Inputs 98 Programming Guide NetLogo 3 1 4 User Manual Some kinds of lists are most easily built using the n values reporter which allows you to construct a list of a specific length by repeatedly running a given reporter You can make a list of the same value repeated or all the numbers in a range or a lot of random numbers or many other possibilities See dictionary entry for details and examples The_values from primitive lets you construct a list from an agentset It reports a list containing each agent s value for the given reporter The reporter could be a simple variable name or a more complex expression even a call to a procedure defined using to report A common idiom is max values from turtles sum values from turtles and so on You can combine two or more lists using the_sentence reporter which concatenates lists by combining their contents into a single larger list Like 1ist sentence normally takes two inputs but can accept any number of inputs if the call is surrounded by parentheses Changing list items Technically lists can t be modified but you can construct new lists based on old lists If you want the new list to replace the old list use set For example set mylist 2 7 5 Bob 3 0 2 mylist is now 2 7 5 Bob 3 0 2 set mylist replace item 2 mylist 10 mylist is now 2 7 10 Bob 3 0 2 The replace item reporter takes three inputs The fir
142. ava so it can run on all major platforms Mac Windows Linux et al It is run as a standalone application Individual models can be run as Java applets inside a web browser Features You can use the list below to help familiarize yourself with the features NetLogo has to offer e System Cross platform runs on Mac Windows Linux et al e Language Fully programmable Simple language structure Language is Logo dialect extended to support agents and concurrency Mobile agents turtles move over a grid of stationary agents patches Create links between turtles to make networks Unlimited numbers of agents and variables Large vocabulary of built in language primitives Integer and double precision floating point math Runs are exactly reproducible cross platform What is NetLogo 1 NetLogo 3 1 4 User Manual e Environment View your model in either 2D and 3D Scalable and rotatable vector shapes Turtle and patch labels Interface builder w buttons sliders switches choosers monitors text boxes Control strip including speed slider Powerful and flexible plotting system Info tab for annotating your model HubNet participatory simulations using networked devices Agent monitors for inspecting and controlling agents Export and import functions export data save and restore state of model BehaviorSpace tool used to collect data from multiple runs of a model System Dynamics Modeler e Web Models
143. ave many settings each of which can take a range of values Together they form what in mathematics is called a parameter space for the model whose dimensions are the number of settings and in which every point is a particular combination of values Running a model with different settings and sometimes even the same ones can lead to drastically different behavior in the system being modeled So how are you to know which particular configuration of values or types of configurations will yield the kind of behavior you are interested in This amounts to the question of where in its huge multi dimension parameter space does your model perform best For example suppose you want speedy synchronization from the agents in the Fireflies model The model has four sliders number cycle length flash length and number flashes that have approximately 2000 100 10 and 3 possible values respectively That means there are 2000 100 10 3 600 000 possible combinations of slider values Trying combinations one at a time is hardly an efficient way to learn which one will evoke the speediest synchronization BehaviorSpace offers you a much better way to solve this problem If you specify a subset of values from the ranges of each slider it will run the model with each possible combination of those values and during each model run record the results In doing so it samples the model s parameter space not exhaustively but enough so that
144. ble in the Models Library The Models Library The library contains five sections Sample Models Curricular Models Code Examples HubNet Calculator Activities HubNet Computer Activities Tutorial 1 Models 35 NetLogo 3 1 4 User Manual Sample Models The Sample Models section is organized by subject area and currently contains more than 180 models We are continuously working on adding new models to it so come visit this section at a later date to view the new additions to the library Some of the folders in Sample Models have folders inside them labeled unverified These models are complete and functional but are still in the process of being reviewed for content accuracy and quality of code Curricular Models These are models designed to be used in schools in the context of curricula developed by the CCL at Northwestern University Some of these are models are also listed under Sample Models others are unique to this section See the info tabs of the models for more information on the curricula they go with Code Examples These are simple demonstrations of particular features of NetLogo They ll be useful to you later when you re extending existing models or building new ones For example if you wanted to put a histogram within your model you d look at Histogram Example to find out how HubNet Calculator amp Computer Activities This section contains participatory simulations for use in the classroom For more info
145. ble pcolor Should you need to perform this calculation in some other context use the wrap color primitive If you want a color that s not on the chart more can be found between the integers For example 26 5 is a shade of orange halfway between 26 and 27 This doesn t mean you can make any color in NetLogo the NetLogo color space is only a subset of all possible colors A fixed set of discrete 90 Programming Guide NetLogo 3 1 4 User Manual hues Starting from one of those hues you can either decrease its brightness darken it or decrease its saturation lighten it but you cannot decrease both brightness and saturation Also for display color values are rounded to the nearest 0 1 so for example there s no visible difference between 26 5 and 26 52 There are a few primitives that are helpful for working with color shades The scale color primitive is useful for converting numeric data into colors And shade of will tell you if two colors are shades of the same basic hue For example snade of orange 27 is true because 27 is a lighter shade of orange Code Example Scale color Example shows you how to use the scale color reporter For many models the NetLogo color system is a convenient way of expressing colors But sometimes you d like to be able to specify colors the conventional way by specifying HSB hue saturation brightness or RGB red green blue values The hsb and rgb primitives let you do this extract hsb a
146. bnet send view generates a hubnet exit message Note This is an experimental primitive and its behavior may change in a future version See the HubNet Authoring Guide for details hubnet set client interface hubnet set client interface client type client info If client type is COMPUTER client info is a list containing a string with the file name and path relative to the model to the file which will serve as the client s interface This interface will be sent to any clients that log in hubnet set client interfac COMPUTER clients Disease client nlogo 7 when clients log in they will will get the 7 interface described in the file 77 clients Disease client nlogo relative to 7 the location of the model Future versions of HubNet will support other client types Even for Computer HubNet the meaning of the second input to this command may change See the HubNet Authoring Guide for details if 226 Primitives Dictionary NetLogo 3 1 4 User Manual if condition commands Reporter must report a boolean true or false value If condition reports true runs commands The reporter may report a different value for different agents so some agents may run commands and others don t if xcor gt O set color blue 5 turtles on the right half of the view 5 turn blue See also ifelse ifelse value ifelse ifelse reporter commands commands2 Reporter must report a boolean true or false
147. button code only at the end To ensure that put no display at the beginning of the code and display at the end Note also that NetLogo will never draw on screen when inside a without interruption block Turtle and patch forever buttons There is a subtle difference between putting commands in a turtle or patch forever button and putting the same commands in an observer button that does ask turtles orask patches An ask doesn t complete until all of the agents have finished running all of the commands in the ask So the agents as they all run the commands concurrently can be out of sync with each other but they all sync up again at the end of the ask The same isn t true of turtle and patch forever buttons Since ask was not used each turtle or patch runs the given code over and over again so they can become and remain out of sync with each other At present this capability is very rarely used in the models in our Models Library A model that does use the capability is the Termites model in the Biology section of Sample Models The go button is a turtle forever button so each termite proceeds independently of every other termite and the observer is not involved at all This means that if for example you wanted to add a plot to the model you would need to add a second forever button an observer forever button and run both forever buttons at the same time At present NetLogo has no way for one forever button to start another B
148. ccurs in practice during actual NetLogo model runs or only occurs in the context of our testing regimen The bug in the Sun s Java VM and not in NetLogo itself We hope that only the exp reporter is affected but we can t be entirely certain of this NetLogo users are encouraged to visit http developer java sun com developer bugParade bugs 5023712 html free registration required and vote for Sun to fix this bug e If NetLogo cannot find the font Lucida menus will be illegible This has been known to happen on Fedora Core 3 after upgrading packages Restarting the X Font Server xfs has resolved the problem in all reported cases e Sun s 1 5 0 Java runtime has display problems with GTK 2 0 and NetLogo Issues may include windows not updating properly interface elements being strangely sized menus being cut off at the bottom and weird characters appearing on the view To avoid these issues you can use Sun s j2sdk1 4 2 10 Also the JDK6 beta release from Sun does quite well Known issues with computer HubNet See the HubNet Guide for a list of known issues with computer HubNet Unimplemented StarLogoT primitives The following StarLogoT primitives are not available in NetLogo Note that many StarLogoT primitives such as count turtles with are intentionally not included in this list because NetLogo allows for the same functionality with the new agentset syntax e maxint minint maxnum minnum e import turtles import patches imp
149. ce phrase To find a particular procedure definition in your code use the Procedures popup menu in the Procedures Toolbar The menu lists all procedures in alphabetical order The Shift Left Shift Right Comment and Uncomment items on the Edit menu are used in the procedures tab to change the indentation level of your code or add and remove semicolons which mark comments from sections of code Interface Guide 81 NetLogo 3 1 4 User Manual For more information about writing procedures read Tutorial 3 Procedures and the Programming Guide Information Tab The Information tab provides an introduction to the model and an explanation of how to use it things to explore possible extensions and NetLogo features It is very helpful when you re first exploring a model Interface Procedures YH Find Edit This model explores the stability of predator prey ecosystems The construction of this model is described in two papers by Wilensky amp Reisman referenced below Such systems are called unstable when they tend to result in extinction for one or more species involved In contrast systems are stable when they tend to maintain themselves over time despite fluctuations in population sizes There are two main variations to this model In the first variation wolves and sheep wonder randomly around the landscape while the wolves look for sheep to prey on Each step costs the wolves energy and they must eat sh
150. cedure before any commands See also_let log log number base Reports the logarithm of number in base base show log 64 2 gt 6 See also In Primitives Dictionary 239 NetLogo 3 1 4 User Manual loop loop commands Runs the list of commands forever or until the current procedure exits through use of the_stop command or the report command Note In most circumstances you should use a forever button in order to repeat something forever The advantage of using a forever button is that the user can click the button to stop the loop Iput Iput value list Adds value to the end of a list and reports the new list 7 suppose mylist is 2 7 10 Bob set mylist lput 42 mylist 7 mylist now is 2 7 10 Bob 42 map map reporter list map reporter list list2 With a single list the given reporter is run for each item in the list and a list of the results is collected and reported In reporter use_ to refer to the current item of list show map round 1 1 2 2 2 7 gt 1 2 3 show map 1 2 3 gt 1 4 9 With multiple lists the given reporter is run for each group of items from each list So it is run once for the first items once for the second items and so on All the lists must be the same length In reporter use_ 1 through_2n to refer to the current item of each list Some examples make this clearer show map 1 2 1 2 3 2 4 6 gt 3 6 9 show map
151. ch center when its xcor and ycor are multiples of 1 0 patch ahead 1 is reporting the same patch my turtle is already standing on Why See previous answer It s the same issue This might not be the meaning of ahead you were expecting With pat ch ahead you must specify the distance ahead that you want to look If you want to know the next patch a turtle would cross into if it moved forward continuously it is possible to find that out See Next Patch Example in the Code Examples section of the Models Library How do give my turtles vision You can use in radius to let a turtle see a circular area around it Several primitives let the turtle look at specific points The pat ch ahead primitive is useful for letting a turtle see what is directly in front of it If you want the turtle to look in another direction besides straight ahead try patch left and ahead and patch right and ahead If you want the turtle to have a full cone of vision use the in cone primitive FAQ Frequently Asked Questions 185 NetLogo 3 1 4 User Manual You can also find out the next patch a turtle would cross into if it moved forward continuously See Next Patch Example in the Code Examples section of the Models Library Can agents sense what s in the drawing layer No If you want to make marks that agents can sense use patch colors Does NetLogo have a command like StarLogo s grab command We don t have such a command You can use th
152. concconononininonononnnnn nn rre 281 UV e a o E li ld 282 A cb Sa pe Du ED Sp Si da ead oa Da SD ADS a NA coat dene 282 LAN dar weit et Acts AO 282 A A O a A NO Ai SD OA O a DA di 282 JL RAS REAR ERR ARE OR ORAR ER ARE RAR QE E PE RR 283 O A A A AA O 283 O ODO Mii a ads 283 LOW ANOS A O eae tte ok CAR a ek al 283 xiv NetLogo 3 1 4 User Manual Table of Contents Primitives Dictionary TOWN A Aa 284 A O O 284 ESA AA e ANS AS AA e A O TA ROO A 4 A A ale 284 turtles at lt Dreedss NE 284 TUS SATO aes set tn a alada 285 tuftles here lt breeds NeGr Give ines ob ieeeetieeh a eit 285 turtles on lt DTBedS gt OM cooccccncccnncncnnanononcnnnnonononcnnnnnnn nano non rnnn arena ceara renan anna nana 286 turtles own lt DIrBedS gt QOWO nccccoccccnccnonanoconcnnonncnnnnanno narco nora nana n nana n rn narra anna narrar 286 Pie eG ase aa AE 287 o ce tit A eet Sees 287 PAINTS es ce es e Ad PR ed a A Be 287 UIP E E T RR AO PODE RR DR RR NR 287 OPA ase 288 USE ICO JA ASPEN lidad OO RR ies reels RARO aida e aaa Aaa a aa 288 US e dde dia ase oo So 288 USCr NOW Tie it a bo i 288 sersinput mein A evar ede eee 289 USE MOSS iio tias 289 USer 0NB 0L 4272 A A A e dea DE da does a e o e 289 LISGr VES OO A Ara 289 A e O A PARRA RE a E RR RS ARDOR Pay wel 290 VAIO OM DRE GER ERR SR RR RR PR EA NR RR ace 290 VAI OS TMOM Sa ceed A RE NRO RD RC DR Re POR ROD RME DDR ARA E DR RE REAR DR ARE CRE RE 290 VAMO e RA a oe 290 AA AMADO ANA OND ti AAA
153. couple more times and see how the arrangement of turtles is different each time Note that some turtles may be right on top of each other Think a bit about what you needed to do to make this happen You needed to make a button in the interface and make a procedure that the button uses The button only worked once you completed both of these separate steps In the remainder of this tutorial you will often have to complete two or more similar steps to add another feature to the model If something doesn t appear to work after you completed what you thought is the final step for that new feature continue to read ahead to see if there is still more to do After reading ahead for a couple of paragraphs you should then go back Tutorial 3 Procedures 49 NetLogo 3 1 4 User Manual over the directions to see if there is any step you might have missed Making the go button Now make a button called go Follow the same steps you used to make the setup button except e For Commands enter go instead of setup e Check the forever checkbox in the edit dialog a gt gt gt 94 Ei 30 808 Button Agent s Observer HH M Forever Commands bo Display name Action key Y Force view update after each run Checking this box produces smoother animation but may make the button run more slowly The forever checkbox makes the button stay down once pressed so its commands run over and over again not just once
154. ctionary NetLogo 3 1 4 User Manual show min values from turtles xcor 7 prints the lowest x coordinate of all the turtles min one of min one of agentset reporter Reports a random agent in the agentset that reports the lowest value for the given reporter If there is a tie this command reports one random agent that meets the condition If you want all such agents use with min instead show min one of turtles xcor ycor 7 reports the first turtle with the smallest sum of coordinates See also with min min pxcor min pycor min pxcor min pycor These reporters give the minimum x coordinate and minimum y coordinate respectively for patches which determines the size of the world Unlike in older versions of NetLogo the origin does not have to be at the center of the world However the minimum x and y coordinates must be less than or equal to zero Note You can set the size of the world only by editing the view these are reporters which cannot be set cct 100 setxy random float min pxcor random float min pycor 7 distributes 100 turtles randomly in the 5 third quadrant See also max pxcor max pycor world width and_world height mod number1 mod number2 Reports number modulo number2 that is the residue of number mod number2 mod is is equivalent to the following NetLogo code numberl floor numberl number2 number2 Note that mod is infix that is it comes between it
155. ctive They will be the ones affected by the commands such as output port on and output port off The user can talk to one or multiple ports at the same time Output ports are typically connected to motors but you could also use bulbs LEDs and relays Output ports are identified by one letter names a b c and d 162 GoGo Extension NetLogo 3 1 4 User Manual Examples 7 talk to all output ports talk to output ports a b er waw 7 will give power to all output ports output port on 7 talk to output ports A and D talk to output ports a d 7 will turn off output ports A and D The other output ports will keep their current state output port off talk to output ports c b 5 turn off remaining output ports output port off ping ping Checks the status of GoGo board This is mostly used to make sure the board is connected to the correct serial port It reports true if the GoGo Board responds to a diagnostic message and false otherwise Example show ping sensor sensor sensor Reports the value of the sensor named sensor as a number Sensors are named by numbers 1 to 8 Value ranges between 0 1023 1023 is returned when there is no sensor attached to the port highest resistance or when the sensor is an open state Zero is returned when the sensor is short circuited no resistance Examples show sensor 1 7 will show the value of sensor 1 foreach 1234567 8 show w
156. d for the activity leader and a networked computer with NetLogo installed for each participant We also suggest an attached projector for the leader to project the entire simulation to the participants Starting an activity You ll find the HubNet activities in NetLogo s Models Library in the HubNet Computer Activities folder We suggest doing a few practice runs of an activity before trying it in front of a class 000 Start HubNet Activity Session name B1101 Y Broadcast server location Open a Computer HubNet model NetLogo will prompt you to enter the name of your new HubNet session This is the name that participants will use to identify this activity Enter a name and press Start NetLogo will open the HubNet Control Center which lets you interact with the HubNet server In each activity you ll see a box in the interface tab labeled QuickStart Instructions This contains step by step instructions to run the activity Click the Next gt gt gt button to advance to the next instruction You as the leader should then notify everyone that they may join To join the activity participants launch the HubNet Client application and enter their name They should see your activity listed and can join your activity by selecting it and pressing Enter If the activity you started is not listed the student can enter the server address manually which can be found in the HubNet Control Center 136 HubNet Guide NetLogo 3 1 4 User
157. de me and watch me turtle commands When in follow or ride mode the observer moves with the subject agent around the world The difference between follow and ride is only visible in the 3D view In the 3D view the user can change the distance behind the agent using the mouse When the observer is following at zero distance from the agent it is actually riding the agent When the observer is in watch mode it tracks the movements of one turtle without moving In both views you will see a spotlight appear on the subject and in the 3D view the observer will turn to face 112 Programming Guide NetLogo 3 1 4 User Manual the subject To determine which agent is the focus you can use the subject reporter Code Example Perspective Example Drawing The drawing is a layer where turtles can make visible marks In the view the drawing appears on top of the patches but underneath the turtles Initially the drawing is empty and transparent You can see the drawing but the turtles and patches can t They can t sense the drawing or react to it The drawing is just for people to look at Turtles can draw and erase lines in the drawing using the pen down and pen erase commands When a turtle s pen is down or erasing the turtle draws or erases a line behind it whenever it moves The lines are the same color as the turtle To stop drawing or erasing use pen up Lines drawn by turtles are normally one pixel thick If you want a different thickness
158. dels in the Models Library use this technique The reason NetLogo doesn t automatically keep track of this is that NetLogo is very flexible about letting you make buttons that do anything that you want them to NetLogo has no one way of knowing which of your buttons should advance the clock and which shouldn t Does NetLogo have arrays What NetLogo calls lists are actually implemented internally as arrays so they have some of the performance characteristics of arrays For example random access using the item reporter takes constant time However they re immutable arrays they cannot be altered except by making a copy and altering the copy so replace item is linear time not constant time because the whole array is copied For most purposes the performance differences between lists and arrays doesn t matter it only matters if you re dealing with very long lists In a future version of NetLogo we plan to change our lists to be ordinary singly linked lists as in other Logo and Lisp implementations At the same time we will also provide real mutable arrays as a separate data type FAQ Frequently Asked Questions 187 NetLogo 3 1 4 User Manual Does NetLogo have associative arrays or lookup tables No but you can use lists to accomplish the same thing though less efficiently See e http groups yahoo com group netlogo users message 2344 e http groups yahoo com group netlogo users message 2346 e http groups yaho
159. duplicates remove item replace item reverse sentence shuffle sort sort by sublist values from 192 Primitives Dictionary NetLogo 3 1 4 User Manual String primitives Operators lt gt lt gt but first but last empty first is string item last length member position remove remove item read from string replace item reverse substring word Mathematical primitives log max mean median min mod modes new seed pi precision random random exponential random float random gamma random int or float random normal random poisson random seed remainder round sin sqrt standard deviation subtract headings sum tan variance Plotting primitives autoplot auto plot off auto plot on clear all plots clear plot create temporary plot pen export plot export all plots histogram from histogram list plot plot name plot pen down ppd plot pen reset plot pen up ppu _plot x max plot x min plot y max plot y min plotxy pod ppu set current plot set current plot pen set histogram num bars set plot pen color set plot pen interval set plot pen mode set plot x range set plot y range Link primitives both ends create lt breed gt from create lt breeds gt from create lt breed gt to create lt breeds gt to create lt breed gt with_ create lt breeds gt with endi _ end in lt breed gt neighbor in lt breed gt neighbors in lt breed gt from is link layout circle layout magspring _layou
160. e move button and drag the mouse up down left and right inside the 3D View while holding down the mouse button To allow the mouse position and state to be passed to the model select the interact button and it will function just as the mouse does in the 2D view To return the observer and focus point to their default positions press the Reset Perspective button or use the reset perspective command Fullscreen Mode To enter fullscreen mode press the Full Screen button to exit fullscreen mode press the Esc key Note Fullscreen mode doesn t work on some computers It depends on what kind of graphics card you have See the_System Requirements for details 3D Shapes Some shapes have true 3D counterparts a 3D circle is actually a sphere in the 3D view so they are automatically mapped to that shape square cube 76 Interface Guide NetLogo 3 1 4 User Manual line half 3D line half car 3D car All other shapes are interpreted from their 2D shapes If a shape is a rotatable shape it is assumed to be a top view and it is extruded as if through a cookie cutter and oriented parallel to the xy plane as in Ants If a shape is non rotatable it is assumed to be a side view so it is drawn always facing the observer and with no thickness as in Wolf Sheep Predation Command Center The Command Center allows you to issue commands directly without adding them to the model s procedures Commands ar
161. e 176 Apple condi 176 tried to run one of the applets on your site but it didn t work What should do 177 Can make my model available as an applet while keeping the code secret 177 Can a model saved as an applet use import world file open and other commands vi NetLogo 3 1 4 User Manual Table of Contents FAQ Frequently Asked Questions thatitead les COPA a O AN 177 Deia a A E ainia 177 Can run NetLogo from a CDB ooocooooccconoccnnnoooncccnnnnncononnnnnonnnnnncnnnnnnnnonnnnrnnnnnnnnnnnnnnnnnnnnnn 177 Why is NetLogo so much slower when unplug My laptop cccconnnocooccncnnnnccnnnnannnonoos 177 How do change how many patches there are errar 178 Can use the mouse to paint in the ViewW occccccnnnoncconnnoncccnnnanonnnnnnncnnnnnnnnnnnnnnnnnnnns 178 How big can my model be How many turtles patches procedures buttons and so on can My model CONAN dies 178 Can import GIS data into Nestor da 179 My model runs slowly How can speed it up eee 179 want to try HubNet Cam A E e ds 180 Can run NetLogo from the command line without the GUlB ooooooooocccccccccnoncoooancnnnnnnnns 180 Can have more than one model open at a time eee 180 Does NetLogo take advantage of multiple processors 2 181 Can distribute NetLogo model runs across a cluster of computers 181 Can use max pxcor or max pycor etc as the minimum or maximum
162. e The on off switch lets you temporarily freeze the display The model keeps running but the contents of the view don t change until you unfreeze it by flipping the switch again Most models run much faster when the view is frozen e The 3D button switches to the 3D View see below Here are the settings for the View accessible by editing the View or by pressing the Edit button in the control strip 8000 World amp View World Location of origin Center HA minimum x coordinate for patches R max pxcor 17 maximum x coordinate for patches minimum y coordinate for patches max pycor 17 Torus 35 x 35 maximum y coordinate for patches Y gt World wraps horizontally Y World wraps vertically View Patch size pixels 12 0 Font size of turtle and patch labels 10 Y Turtle shapes Y Smooth edges slower only affects 3D view Cancel Apply Cok Notice that the settings are broken up into two groups There are World setting and View settings World settings affect the properties of the world that the turtles live in changing them may require resetting the world View settings only affect the appearance of view changing them will not affect the outcome of the model The world settings allow you to define the boundaries and topology of the world At the top of the left side of the world panel you can choose a location for the origin of the world either Center Corner Edge or Cu
163. e instructions you give to the agents in your model This is useful for inspecting and manipulating agents on the fly Tutorial 2 Commands is an introduction to using commands in the Command Center Let s take a look at the design of the Command Center Interface Guide 77 NetLogo 3 1 4 User Manual Command Center A Clear turtles gt set color red patches gt set pcolor white observer gt ask turtle 10 set color blue observer gt ask turtle 1 set color blue observer gt crt 10 x The smaller text box below the large box is where you type a command After typing it press the Return or Enter key to run it To the left of where you type is a popup menu that initially says observer gt You can choose either observer turtles or patches to specify which agents run the command you type Tip a quicker way to change between observer turtles and patches is to use the tab key on your keyboard Accessing previous commands After you type a command it appears in the large scrolling box above the command line You can use Copy on the Edit menu in this area to copy commands and then paste them elsewhere such as the Procedures tab You can also access previous commands using the history popup menu which is the small downward pointing triangle to the right of where you type commands Click on the triangle and a menu of previously typed commands appears so you can pick one to use again Tip a quicker
164. e this window go away without changing the settings e Place your mouse pointer next to but still outside of the view You will notice that the pointer turns into a crosshair e Hold down the mouse button and drag the crosshair over the view The view is now selected which you know because it is now surrounded by a gray border e Drag one of the square black handles The handles are found on the edges and at the corners of the view e Unselect the view by clicking anywhere in the white background of the Interface tab e Press the Edit button again and look at the settings What numbers changed Tutorial 1 Models 33 NetLogo 3 1 4 User Manual What numbers didn t change The NetLogo world is a two dimensional grid of patches Patches are the individual squares in the grid In Wolf Sheep Predation when the grass switch is on the individual patches are easily seen because some of them are green while others are brown Think of the patches as being like square tiles in a room with a tile floor By default exactly in the middle of the room is a tile labeled 0 0 meaning that if the room was divided in half one way and then the other way these two dividing lines would intersect on this tile We now have a coordinate system that will help us locate objects within the room How many tiles away is the 0 0 tile from the right side of the room How many tiles away is the 0 0 tile from the left side of the roo
165. e without interruption primitive to arrange exclusive interaction between agents For example turtles own mate to setup ask turtles set mate nobody end to find mate turtle procedure without interruption if mate nobody let candidate one of other turtles her with mate nobody if candidate nobody set mate candidate set mate of candidate self end Using without interruption ensures that while a turtle is choosing a mate all other agents are frozen This makes it impossible for two turtles to choose the same mate I tried to put at after the name of a variable for example variable at 1 0 but NetLogo won t let me Why not This syntax was supported by StarLogoT and some beta versions of NetLogo but was removed from NetLogo 1 0 Instead for a patch variable write e g pcolor of patch at 1 0 and fora turtle variable write e g color of one of turtles at 1 0 I m getting numbers like 0 10000000004 and 0 799999999999 instead of 0 1 and 0 8 Why See the Math section of the Programming Guide in the User Manual for a discussion of this issue The documentation says that random float 1 0 might return 0 0 but will never return 1 0 What if want 1 0 to be included It really doesn t matter Even if 1 0 were a possible result it would only come up approximately 1 in 2164 tries which means you d be waiting hundreds of years before it ever came up exactly 1 0 Nonetheless if you feel i
166. e xcor mouse ycor red movie cancel movie cancel Cancels the current movie movie close movie close Stops the recording of the current movie movie grab view movie grab interface movie grab view movie grab interface Adds an image of the current view or the interface panel to the current movie 7 make a 20 step movie of the current view setup movie start out mov repeat 20 movie grab view go movie close movie set frame rate movie set frame rate frame rate Sets the frame rate of the current movie The frame rate is measured in frames per second If you do not explicitly set the frame rate it defaults to 15 frames per second Must be called after movie start but before movie grab view or movie grab interface See also movie status movie start Primitives Dictionary 245 NetLogo 3 1 4 User Manual movie start filename Creates a new movie filename specifies a new QuickTime file where the movie will be saved so it should end with mov See also movie grab view movie grab interface movie cancel movie status movie set frame rate movie close movie status movie status Reports a string describing the current movie print movie status gt No movie movie start print movie status gt 0 frames Framerate 15 0 movie grab view print movie status 1 frames Framerate 15 0 Size 315x315 __my lt breeds gt __my lt breeds gt Reports an agentset of all
167. ection of the Programming Guide for more information To fix your model so that it works regardless of the wrapping settings use one of these two commands instead setxy random xcor random ycor setxy random pxcor random pycor 184 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual The two commands are a bit different The first command puts the turtle on a random point in the world The second command puts the turtle on the center of a random patch The random xcor random ycor random pxcor and random pycor primitives are new in NetLogo 3 1 How do take the negative of a number Any of these ways x UR Or Sy xe With the first way the parentheses are required My turtle moved forward 1 but it s still on the same patch Why Moving forward 1 is only guaranteed to take a turtle to a new patch if the turtle s heading is a multiple of 90 that is exactly north south east or west It s because the turtle might not be standing in the center of a patch It might be near a corner For example suppose your turtle is close to the southwest corner of a patch and is facing northeast The length of the patch diagonal is 1 414 the square root of two so fd 1 will leave the turtle near the northeast corner of the same patch If you don t want to have to think about these issues one possibility is to write your model in such a way that your turtles always come to rest on patch centers A turtle is on a pat
168. ed See also_uphill4 downhill downhill4 uphill4 uphill4 patch variable x Reports the turtle heading between 0 and 359 degrees as a multiple of 90 degrees in the direction of the maximum value of the variable patch variable of the four patches to the north south east and west of the turtle If there are multiple patches that have the same greatest value a random patch from those patches will be selected See also_uphill downhill downhill4 user directory user directory Opens a dialog that allows the user to choose an existing directory on the system It reports a string with the absolute path or false if the user cancels set current directory user directory Assumes the user will choose a directory user file user file Opens a dialog that allows the user to choose an existing file on the system It reports a string with the absolute file path or false if the user cancels file open user fil Assumes the user will choose a file user new file user new file Opens a dialog that allows the user to choose a location and name of a new file to be created It reports a string with the absolute file path or false if the user cancels file open user new fil Assumes the user will choose a file 288 Primitives Dictionary NetLogo 3 1 4 User Manual Note that this reporter doesn t actually create the file normally you would create the file using file open as in the example user input user input
169. ed by this link turtle 7 Let a directed link turtle L be connected from N1 to N2 ask L show __both ends displays an agentset consisting of N1 and N2 198 Primitives Dictionary NetLogo 3 1 4 User Manual This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details breed breed k This is a built in turtle variable It holds the agentset of all turtles of the same breed as this turtle For turtles that do not have any particular breed this is the turtles agentset of all turtles You can set this variable to change a turtle s breed See also_breed Example breed cats cat breed dogs dog 7 turtle code if breed cats show meow set breed dogs show woof breed breed lt breeds gt lt breed gt This keyword like the globals turtles own and patches own keywords can only be used at the beginning of the Procedures tab before any procedure definitions It defines a breed The first input defines the name of the agentset associated with the breed The second input defines the name of a single member of the breed Any turtle of the given breed e is part of the agentset named by the breed name e has its breed built in variable set to that agentset Most often the agentset is used in conjunction with ask to give commands to only the turtles of a particular breed breed mice mouse breed frogs frog
170. eep in order to replenish their energy when they run out of energy they die To allow the population to continue each wolf or sheep has a fixed probability of reproducing at each time step This variation produces interesting population dynamics but is ultimately unstable The second variation includes grass green in addition to wolves and sheep The behavior of the wolves is identical to the first variation however this time the sheep must eat grass in order to maintain their energy when they run out of energy they die Once grass is eaten it will only regrow after a fixed amount of time This variation is more complex than the first but it is generally stable We recommend reading the Information tab before starting the model The Information tab explains what principle is being modeled and how the model was created This display of the Information tab is not editable To edit the content of the Info tab click the Edit button or double click on a word which will also scroll you to the location you clicked on and highlight the word Interface Procedures WHAT IS IT This model explores the stability of predator prey ecosystems The construction of this model is described in two papers by Wilensky amp Reisman referenced below Such systems are called unstable when they tend to result in extinction for one or more species involved In contrast systems are stable when they tend to maintain themselves over time despite fluctuatio
171. eger and sometimes a floating point number now it always reports an integer This primitive mimics the old behavior as follows Primitives Dictionary 263 NetLogo 3 1 4 User Manual If number is positive reports a random number greater than or equal to 0 but strictly less than number If number is negative the number reported is less than or equal to 0 but strictly greater than number If number is zero the result is always zero as well If number is an integer reports a random integer If number is floating point has a decimal point reports a floating point number show random int or float 3 7 prints 0 1 or 2 show random int or float 5 0 7 prints a number at least 0 0 but less than 5 0 for example 4 686596634174661 random pxcor random pycor random pxcor random pycor Reports a random integer ranging from min pxcor or y to max pxcor or y inclusive ask turtles 7 move each turtle to the center of a random patch setxy random pxcor random pycor See also random xcor random ycor random seed random seed number Sets the seed of the pseudo random number generator to the integer part of number The seed may be any integer in the range supported by NetLogo 2147483648 to 2147483647 See the Random Numbers section of the Programming Guide for more details random seed 47823 how random 100 pras how random 100 gt 91 andom seed 47823 how random 100 gt 57 how random 100
172. eing combined Since it can be difficult to develop an intuition about what reduce does here are some simple examples which while not useful in themselves may give you a better understanding of this primitive show reduce 1 2 1 2 3 gt 6 Primitives Dictionary 265 NetLogo 3 1 4 User Manual show reduce 1 2 1 2 3 gt 4 show reduce 2 1 1 2 3 gt 2 show reduce 1 1 2 3 gt 1 show reduce 2 1 2 3 gt 3 how reduc sentence 1 2 1 2 3 4 5 dto SB A 5 how reduce fput 2 1 feut 1 1 2 340519 gt 5 43 2 1 u u Here are some more useful examples 7 find the longest string in a list to report longest string strings report reduce ifelse valu length 1 gt length 2 1 2 strings end show longest string hi there gt there 7 count the number of occurrences of an item in a list to report occurrences x xs report reduce ifelse value 2 x 21 1 1 fput 0 xs end show occurrences 1 1 21312311451 gt 6 7 evaluate the polynomial with given coefficients at x to report eval polynomial coeffs x report reduce x 1 2 coeffs end 7 evaluate 3x 2 2x 1 at x 4 show eval polynomial 3 2 1 4 gt 57 remainder remainder number number2 Reports the remainder when number is divided by number2 This is equivalent to the following NetLogo code numberl int numberl n
173. el Controlling the Model Buttons When a button is pressed the model responds with an action A button can be a once button or a forever button You can tell the difference between these two types of buttons by a symbol on the face of the button Forever buttons have two arrows in the bottom right corners like this Once buttons don t have the arrows like this Once buttons do one action and then stop When the action is finished the button pops back up Forever buttons do an action over and over again When you want the action to stop press the button again It will finish the current action then pop back up Most models including Wolf Sheep Predation have a once button called setup and a forever button called go Many models also have a once button called go once or step once which is like go except that it advances the model by one time step instead of over and over Using a once button like this lets you watch the progress of the model more closely Stopping a forever button is the normal way to stop a model It s safe to pause a model by stopping a forever button then make it go on by pressing the button again You can also stop a model with the Halt item on the Tools menu but you should only do this if the model is stuck for some reason Using Halt may interrupt the model in the middle of an action and as the result the model could get confused e If you like experiment with the setup and go button
174. el For example suppose you want to create 50 turtles with the shape rabbit Provided there is some shape called rabbit in this model give this command to the observer in the command center O gt crt 50 And then give these commands to the turtles to spread them out then change their shape T gt fd random 15 T gt set shape rabbit Voila Rabbits Note the use of double quotes around the shape name Shape names are strings The set default shape command is also useful for assigning shapes to turtles 126 Shapes Editor Guide BehaviorSpace Guide This guide has three parts e What is BehaviorSpace A general description of the tool including the ideas and principles behind it e How It Works Walks you through how to use the tool and highlights its most commonly used features e Advanced Usage How to use BehaviorSpace from the command line or from your own Java code What is BehaviorSpace BehaviorSpace is a software tool integrated with NetLogo that allows you to perform experiments with models It runs a model many times systematically varying the model s settings and recording the results of each model run This process is sometimes called parameter sweeping It lets you explore the model s space of possible behaviors and determine which combinations of settings cause the behaviors of interest Why BehaviorSpace The need for this type of experiment is revealed by the following observations Models often h
175. el available as an applet while keeping the code secret No In order for the applet to operate the model file must be accessible also When you use Save as applet on the File menu the HTML page generated contains a link where the user can download the model file If you want you can remove that link Doing so will make it harder for the user to access the model file but not impossible Can a model saved as an applet use import world file open and other commands that read files Yes but only to read files that are stored in the same directory on your web server as the HTML and model files Applets cannot read files on the user s computer only the web server Usage Can run NetLogo from a CD Yes NetLogo runs fine on a read only file system Why is NetLogo so much slower when unplug my laptop Your computer is switching to power saving mode when unplugged It s normal for this to reduce speed a little but unfortunately there is a bug in Java that drastically slows down Swing applications including NetLogo FAQ Frequently Asked Questions 177 NetLogo 3 1 4 User Manual One workaround is to change the power settings on your computer so it doesn t go into power saving mode when you unplug it If you do this your battery won t last as long Another workaround is to run NetLogo with an option recommended by Sun by editing the NetLogo lax file found in the NetLogo directory under Program Files on your hard drive unle
176. ements ApplicatiON oooocccccccnnnooonccnnnnnnonononnnncnonnnnccnnnnnnnnnnnnnnccnnnnnrnnnnnnnnnnn 13 MINOS A a Deed SE E Da e 13 MIOS A ide 13 Mac OS BAND A A A bei 13 Other platforms Ae 13 System Requirements Saved AppletS coccccoooooocccccccococonononnconnnnnconnnannnnnnnnnnncnnnnnnonnnnnnnnnns 14 System Requirements 3D Vi Wi aiii dades ad ds 14 Operating SYVSIOMS tas Aa 14 Graphics Cards it pra E A aa RE EEEE N 14 Fullscreen MOG Ss 20 38 cence A aS Aaaa a an ariaa E 15 ibrary Conflicts zini a R E A RT 15 Removing an old JOG uta 15 Known ISSUES iaa Aa dera aE aa a A a a sia feudo Sads 17 Known bugs all SYSteMS ee 17 Windows only DUAS ia iaa 17 Macintosh only BUGS siii A A A E A Ad 17 Linux UNIX only bugs cnn nn nrnnnmmnn mms 18 Known issues with computer HUDNet ee cece cece cece ee eeee cece eect tect ee eee cnn cnn nnnnnnnrnnrrnnrnnnnnnes 18 Unimplemented StarLogoT priMitiVeS cocoooocccnnnncccnnnonononnnnnncnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnncccnnnnos 18 Contacting Usa ti daa caras 21 Web ler a Ee ee aE 21 Feedback Questions EdC Laciana ia ia 21 NetLogo 3 1 4 User Manual Table of Contents sample Model Palancia ra Ri iia caia 23 Ata Party aos 23 A nie Soeueneta nd de resilient i Eae dar re E Sire ES RSE 25 Thinking With ModelS oooooooococonoconocononononononononononnnonnnonnnonnnonnnnnnnnnnnnnnnnnnnnnnnnnnnonnnnnnnonnnenineniness 26 What s Next a A lis 26 Tutorial 41 3 Model
177. enonnnonennnnnnnnnnnnnnnnnnnnnnnnnrnnnnnnnnnnnnennnenneneneeninen 47 Making the go DUT ON ccccccccnccnnccnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnenineninnnncnn 50 Experimenting with COMMAndS cccccccnnccnncconnnennnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnennnnnnnnnnneninin 51 Patches and variables wine acta A A etree bas 52 Turtle VADO woe eect esc e A E 53 MONOS 22d noc eo A Beh a do AA a aa JOAO A a ate th ee 55 Switches A ADS ano 57 MOTE PrOCCQUIES cotas AAA Ao 59 nd o dio URNA DR RDI PR GR RR DR RARO QREN RI RD ER DO DR Oe RR 60 Global Varia less ad 63 Some more detal ls a isca 64 Whats NOXE Gage dann lone DE CEU cacau tones alin ba uenaveeaaceteld 65 Appendix Gomplete COAG corista Ao 66 Interface GUIDO iii aiii 69 MENUS it A A AA ae a ete a 69 Tabs de AE thc Mates Dois once ies het duna dao Dra CU E ole Shah la Dista Nea ears is De ata a ta 71 lier aCe A RA Rea ook a 71 NetLogo 3 1 4 User Manual Table of Contents Interface Guide Working with Interface EleMentS ccccccconooooocccncccnonnnonononcnnnonncnnnnnnonnnnnncnnnnnnnrnnnnnnnnnnns 71 Ghart Interface Toolbar o tic 72 The 2D and 3D VieWS cooccccnoccccncnconccnonococonccnonanononcnnoncccnnnnononcnnonaranoncnnonarcnnncnnonannanaciananans 73 COMMANA Cetec ie 77 Pl ni T a re ii tl 79 Procedures TaD seca ti O A A A a E da A a 80 ic ce ado be EEEE de vaste cheats SEREI D Tea dees ad ES Sra EE REA ASS de susan 82 Inf
178. ent Reports the heading from this agent to the given agent If wrapping is allowed by the topology and the wrapped distance around the edges of the view is shorter than the on screen distance towards will report the heading of the wrapped path Note asking for the heading from an agent to itself or an agent on the same location will cause a runtime error towardsxy towardsxy x y k Reports the heading from the turtle or patch towards the point x y If wrapping is allowed by the topology and the wrapped distance around the edges of the view is shorter than the on screen distance towardsxy will report the heading of the wrapped path Note asking for the heading to the point the agent is already standing on will cause a runtime error turtle turtle number Reports the turtle with the given ID number or_nobody if there is no such turtle number must be an integer set color of turtle 5 red turtle with id number 5 turns red ask turtle 5 set color red 7 another way to do the same thing turtles turtles Reports the agentset consisting of all turtles show count turtles 7 prints the number of turtles turtles at lt breeds gt at 284 Primitives Dictionary NetLogo 3 1 4 User Manual turtles at dx dy lt breeds gt at dx dy Reports an agentset containing the turtles on the patch dx dy from the caller including the caller itself if it s a turtle If the caller is the observer dx and dy are ca
179. erario idea 150 SUM A a 150 Luto a gt es ERIEN er ot ao e 150 Extension development tipS ccoccccccccccnnncnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnennnenenineness 153 CONCIUSION encara 154 Controlling GUI s sets ee DAS RUSSA E cea ea eee 155 Note on Memory USAGE acia aid 155 Example WING 155 Example Neadless ooccccccccccocccnnccnnccnnnennnennnenonnnnnnnnennnnnnnrrnnrrnnr rr rre 156 BONA MOS PACO extieruaiinians a era Ud a ga 157 Other OPORE os sink cote eeu tie tiated Da a fi So ieia 158 CONCIUSION ear E NATAS ETES iia 158 GOGO Extension ui lidiar cda 159 What is the GOGO Board Perene o n a a a a a ncnononancnn nono E AEA 159 HOW 10 Geta GOGO BO AA 159 Installing the GOGO Extension e eeerrrrererenanananararereaaaaaaananareresaaaana 159 MacOS XLS DIOS 159 W Algo o VESPA CNP a RD SN A RR ROM RAN RN 160 Lihuxcand OlNerS sia ares a eae gados 160 Using the GoQo EXMeNSIONM quai asas iia 160 nd dA ADM Ass PARRA RR RE PARA RAR E RR AR ARDER RR UU PARE REDE DR Dd 161 QOG0 ClOSE Yi fii aa ies He ieee A aa 161 RN 161 GOGO SOD A E OO 161 QOQO DOMS is 161 OUTpUIEDONECO AS iii oi iaa 162 OUTPUTS DOM Offa a deetraseuidalted fenton 162 ouipui pori reverse reste eee aaaae nent ee eeeeeaaaaa ne eeeeesesaasaaaaaeeeeeaeseanenaaes 162 OUutpUt port that this WaAY ecceecceeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeegeeeneeeseeeeeeeeeeeees 162 TA lK tO O0UTDUTEPOTES AA A oda 16
180. ers like 0 10000000004 and 0 799999999999 instead of 0 1 and 0 8 Why e The documentation says that random float 1 0 might return 0 0 but will never return 1 0 What if want 1 0 to be included e How can use different patch neighborhoods circular Von Neumann Moore etc e Can connect turtles with lines to indicate connections between them e How can keep two turtles from occupying the same patch e How can find out if a turtle is dead e How do find out how much time has passed in my model e Does NetLogo have arrays e Does NetLogo have associative arrays or lookup tables e How can convert an agentset to a list or vice versa 172 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual e How does NetLogo decide when to switch from agent to agent when running code e How do stop foreach e How do make an empty agentset General Why is it called NetLogo The Logo part is because NetLogo is a dialect of the Logo language Net is meant to evoke the decentralized interconnected nature of the phenomena you can model with NetLogo It also refers to HubNet the networked participatory simulation environment included in NetLogo What programming language was NetLogo written in NetLogo is written entirely in Java version 1 4 1 How do cite NetLogo in an academic publication NetLogo itself Wilensky U 1999 NetLogo _http ccl northwestern edu netlogo Center for Connected Learni
181. ersions of NetLogo these primitives were used in many situations where the new patch ahead primitive is now more appropriate E empty empty list empty string Reports true if the given list or string is empty false otherwise Note the empty list is written The empty string is written end end Used to conclude a procedure See to and to report Primitives Dictionary 209 NetLogo 3 1 4 User Manual _ end _ endi Reports the first end of a link In a directed link the direction of the link is from end1 to the end2 Let a directed link L be connected from N1 to N2 ask L show __endl prints N1 Even though in an undirected link order of nodes is not important end1 is deterministic and reports the same node on repeated calls by an undirected link This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details _ end2 _ end2 Reports the second end of a link In a directed link the direction of the link is from end1 to the end2 Let a directed link L be connected from N1 to N2 ask L show __end2 prints N2 Even though in an undirected link order of nodes is not important end2 is deterministic and reports the same node from repeated calls by an undirected link This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details erro
182. es place once the agent is done running without interruption Note that display and no display operate independently of the switch in the view control strip that freezes the view See also no display Primitives Dictionary 207 NetLogo 3 1 4 User Manual distance distance agent Reports the distance from this agent to the given turtle or patch The distance to or a from a patch is measured from the center of the patch Turtles and patches use the wrapped distance around the edges of the view if wrapping is allowed by the topology and the wrapped distance is shorter than the on screen distance distancexy distancexy xcor ycor x Reports the distance from this agent to the point xcor ycor The distance from a patch is measured from the center of the patch Turtles and patches use the wrapped distance around the edges of the view if wrapping is allowed by the topology and the wrapped distance is shorter than the on screen distance if distancexy 0 0 gt 10 set color green 7 all turtles more than 10 units from 7 the center of the screen turn green downhill downhill patch variable Reports the turtle heading between 0 and 359 degrees in the direction of the minimum value of the variable patch variable of the patches in a one patch radius of the turtle This could be as many as eight patches or as few as one patch depending on the position of the turtle within its patch and the topology of the world
183. es visible again Primitives Dictionary 277 NetLogo 3 1 4 User Manual Note This command is equivalent to setting the turtle variable hidden to false See also hide turtle shuffle shuffle list Reports a new list containing the same items as the input list but in randomized order show shuffle gt 5241 3 show shuffle gt 13524 123 4 5 123 4 5 sin sin number Reports the sine of the given angle Assumes angle is given in degrees show sin 270 gt 1 0 size size This is a built in turtle variable It holds a number that is the turtle s apparent size The default size is 1 0 which means that the turtle is the same size as a patch You can set this variable to change a turtle s size sort sort list sort agentset If the input is a list reports a list containing the same items as the input list but in ascending order If there is at least one number in the list the list is sorted in numerically ascending order and any non numeric items of the input list are discarded If there are no numbers but at least one string in the list the list is sorted in alphabetically ascending order and any non string items are discarded If the input is an agentset or a list of agents reports a list never an agentset of agents If the agents are turtles they are listed in ascending order by who number If the agents are patches they are listed left to right top to bottom show sort 3 1 4 2 gt 1
184. et Message WaitidQP ooooccconnnccccnononooonnnnccnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnrnnnnnnnnnnnnnncnnnnnnns 225 NetLogo 3 1 4 User Manual Table of Contents Primitives Dictionary A PAR NPR O SS RD ON RR ee RS RA 225 DUDA CIS ui ta 225 NUDNE SONOO ViBeW occccnoccccnccccnncoconccnoncccnnnnnnonocanoncnnoncnno narco nn nano manco nn nano ncnno nara nnn cana nacnananas 226 hubnet set client interface cccccccececceccseuscesesceccuseecusccsenecseueasnducesceeeeevecentuaeevacees 226 soothe o ORO Aa E O qa a hates tet Aen si Deter in senate o pta ni athe 226 I Sees Sates cca e AD E age e ech eae et ae Sa a AQ aa 226 A A OA 227 A O 227 IM PO MOWING n o a PR DD RED RR OD 228 a A RR RR OR aecearna send ROTOR RR 228 IMIPOM Wo E SENDER RR RR RE ERR NR E NNE PAR SRD E RR 228 A A RR EA oh 229 I lt br88d gt ANSIADO ta DAE makati Da da a 229 IN lt breed gt Ne iQhbors ececceceeeeeeeeece cee eeeeeeeeeeeaeeeeeeeeeeeeeaeeeaeeeeeseseeeseeneeenseeee 230 AA 230 A RO 231 MAXSOMC O lite ts e o a tol Ait Bee 241 m x pOor MaX PVYCOL aos 241 MA A a e O tunica aa 241 xi NetLogo 3 1 4 User Manual Table of Contents Primitives Dictionary xii IMO GAM PAD DR ANNA RR ERRAR A NA URV REV ED RS 242 member NRO 242 MIE er e AA dB RA A ae AME A MD DAR E O AR AT 242 MITIN RAR te Sa RR 243 MIN PXCOEMIN pPVCOE caida aaa 243 MOO A O 243 MIES o E one o TAD E A Dee 2 UR Bie aio bie 244 MOSCA ERES RO DR ERR E DRA EU RR 24
185. etLogo 3 1 4 User Manual Conclusion Don t forget to consult the NetLogo API Specification for full details on these classes interfaces and methods Note that there is no way for the modeler to get a list of commands and reporters provided by an extension so it s important that you provide adequate documentation The extensions facility is considered experimental This initial API doesn t include everything you might expect Some facilities exist but are not yet documented If you don t see a capability you want please let us know Do not hesitate to contact us at feedback Occl northwestern edu with questions as we may be able to find a workaround or provide additional guidance where our documentation is thin Hearing from users of this API will also allow us to appropriately focus our efforts for future releases We are committed to making NetLogo flexible and extensible and we very much welcome your feedback 154 Extensions Guide Controlling Guide NetLogo can be invoked from another Java program and controlled by that program For example you might want to call NetLogo from a small program that does something simple like automate a series of model runs This section of the User Manual introduces this facility for Java programmers We ll assume that you know the Java language and related tools and practices Note The controlling facility is considered experimental It is likely to continue to change and grow Code you write
186. etLogo interface in order and explains its function For a detailed description and specifics about writing procedures refer to the Programming Guide All of the primitives are listed and described in the the_Primitives Dictionary Also you can continue experimenting with and expanding this model if you d like experimenting with different variables and behaviors for the agents Alternatively you may want to revisit the first model in the tutorial Wolf Sheep Predation This is the model you used in Tutorial 1 In the Wolf Sheep Predation model you saw sheep move around consume resources that are replenished occasionally grass reproduce under certain conditions and die if they ran out of resources But that model had another type of creature moving around wolves The addition of wolves requires some additional procedures and some new primitives Wolves and sheep are two different breeds of turtle To see how to use breeds study Wolf Sheep Predation Tutorial 43 Procedures 65 NetLogo 3 1 4 User Manual Alternatively you can look at other models including the many models in the Code Examples section of the Models Library or even go ahead and build your own model You don t even have to model anything It can be interesting just to watch patches and turtles forming patterns to try to create a game to play or whatever Hopefully you have learned some things both in terms of the NetLogo language and about how to go about bui
187. etes all temporary plot pens resets the plot to its default values for x range y range etc and resets all permanent plot pens to their default values The default values for the plot and for the permanent plot pens are set in the plot Edit dialog which is displayed when you edit the plot If there are no plot pens after deleting all temporary pens that is to say if there are no permanent plot pens a default plot pen will be created with the following initial settings e Pen down e Color black e Mode O line mode e Name default e Interval 1 0 See also clear all plots clear turtles ct clear turtles S Kills all turtles 202 Primitives Dictionary NetLogo 3 1 4 User Manual See also_die color color k This is a built in turtle variable It holds the color of the turtle You can set this variable to make the turtle change color See also_pcolor cos cos number Reports the cosine of the given angle Assumes the angle is given in degrees show cos 180 gt 1 0 count count agentset Reports the number of agents in the given agentset show count turtles 7 prints the total number of turtles show count patches with pcolor red 7 prints the total number of red patches __create lt breed gt to __create lt breed gt from _ create lt breed gt with create lt breed gt to agent commands _ create lt breed gt from agent commands _ create lt breed gt with agent
188. ettings and observe a few runs to get a full understanding of the model As you are using the Traffic Basic model have you noticed any additions you would like to make to the model Looking at the Traffic Basic model you may notice the environment is fairly simple a black background with a white street and number of blue cars and one red car Changes that could be made to the model include changing the color and shape of the cars adding a house or street light creating a stop light or even creating another lane of traffic Some of these suggested changes are cosmetic and would enhance the look of the model while the others are more behavioral We will be focusing more on the simpler or cosmetic changes throughout most of this tutorial Tutorial 3 will go into greater detail about behavioral changes which require changing the Procedures tab To make these simple changes we will be using the Command Center The Command Center The Command Center is located in the Interface Tab and allows you to enter commands or directions to the model Commands are instructions you can give to NetLogo s agents turtles patches and the observer Refer to the Interface Guide for details explaining the different parts of the Command Center Tutorial 2 Commands 37 NetLogo 3 1 4 User Manual In Traffic Basic e Press the setup button e Locate the Command Center e Click the mouse in the white box at the bottom of the Command Center
189. ettings is useful if you just want to do many runs with the current settings What order you list the variables in determines what order the runs will be done in All values for a later variable will be tried before moving to the next value for an earlier variable So for example if you vary both x and y from 1 to 3 and x is listed first then the order of model runs will be x 1 y 1 x 1 y 2 x 1 y 3 x 2 y 1 and so on Repetitions Sometimes the behavior of a model can vary a lot from run to run even if the settings don t change if the model uses run numbers If you want to run the model more than once at each combination of settings enter a higher number here than one Measure runs using these reporters This is where you specify what data you want to collect from each run For example if you wanted to record how the population of turtles rose and fell during each run you would enter count tiles BehaviorSpace Guide 129 NetLogo 3 1 4 User Manual You can enter one reporter or several or none at all If you enter several each reporter must be on a line by itself for example countrogs count mice Count soared s If you don t enter any reporters the runs will still take place This is useful if you want to record the results yourself your own way such as with the export wor1d command Measure runs at every tick Normally NetLogo will measure model runs at every tick using the reporters you entered in the previous bo
190. eview gray 5 7 a 9 9 9999 red 15 18 19 19 9999 orange 25 28 29 29 9999 brown 35 a 19 19 9999 yellow 45 48 49 49 9999 green 55 6a 59 9 9999 lime 65 ca 69 69 9999 turquoise 75 7 79 79 9999 cyan 85 aa ag 89 9999 sky 95 se se 99999 4 blue 105 108 109 109 9999 violet 115 118 119 119 9999 magenta 125 128 129 129 9999 pink 135 e om 138 139 139 9999 Copy selected color black M Numbers 10 0 50 0 1 Increment When you click on any one of the color swatches or the color buttons that color will be displayed against all of the other standard colors along the right edge of the dialog and black and white along the top In the bottom left corner the value of the currently selected color is displayed so you can copy the color and easily insert it into your code In the bottom right corner there are three increment options 1 0 5 and 0 1 These numbers indicate the difference between two adjacent swatches When the increment is 1 there are 10 different shades in each row so when the increment is 0 1 there are 100 different shades in each row Note If you use a number outside the 0 to 140 range NetLogo will repeatedly add or subtract 140 from the number until it is in the O to 140 range For example 25 is orange so 165 305 445 and so on are orange too and so are 115 255 395 etc This calculation is done automatically whenever you set the turtle variable color or the patch varia
191. ey leave some extra room 25 if growing horizontally 10 if growing vertically If you want to turn off this feature edit the plot and uncheck the Autoplot checkbox At present it is not possible to enable or disable this feature only on one axis it always applies to both axes Temporary plot pens Most plots can get along with a fixed number of pens But some plots have more complex needs they may need to have the number of pens vary depending on conditions In such cases you can make temporary plot pens from code and then plot with them These pens are called temporary because they vanish when the plot is cleared by the clear plot clear all plots or clear all commands To create a temporary plot pen use the create temporary plot pen command Once the pen has been created you can use it like any ordinary pen By default the new pen is down is black in color has an interval of 1 0 and plots in line mode Commands are available to change all of these settings see the Plotting section of the Primitives Dictionary Using a Legend You can show the legend of a plot by clicking on the word Pens in the upper right corner of the plot If you don t want a particular pen to show up in the legend you can uncheck the Show in Legend checkbox for that pen in the plot edit dialog Conclusion Not every aspect of NetLogo s plotting system has been explained here See the Plotting section of the Primitives Dictionary for information on add
192. f a random patch shade of shade of color1 color2 Reports true if both colors are shades of one another false otherwise show shade of blue red gt false show shade of blue blue 1 gt true show shade of gray white gt true 276 Primitives Dictionary NetLogo 3 1 4 User Manual shape shape This is a built in turtle variable It holds a string that is the name of the turtle s current shape You can set this variable to change a turtle s shape New turtles have the shape default unless the a different shape has been specified using set default shape Example ask turtles set shape wolf 7 assumes you have made a wolf 7 shape in NetLogo s Shapes Editor See also set default shape shapes shapes shapes Reports a list of strings containing all of the turtle shapes in the model New shapes can be created or imported from the shapes library or from other models in the Shapes Editor show shapes gt default airplane arrow box bug ask turtles set shape one of shapes show show value Prints value in the Command Center preceded by the calling agent and followed by a carriage return The calling agent is included to help you keep track of what agents are producing which lines of output Also all strings have their quotes included similar to_write See also_print type and_write See also output show show turtle st show turtle The turtle becom
193. fixed bug where sprout 0 caused Java exception fixed bug where using sort with an invalid input could cause a Java exception e other fixes 4 fixed Windows only bug where saved model files could include inconsistent line ending characters e extensions new command in the sound extension play note later can be used to play a musical phrase Version 3 1 1 June 16 2006 e content corrections to User Manual new biology models Daisyworld Wolf Sheep Stride Inheritance What s New NetLogo 3 1 4 User Manual improved models Ethnocentrism clearer code corrected reference Bug Hunt Camouflage upgraded now verified Fire improved info tab GasLab Two Gas bug fix Heatbugs now verified GasLab Single Collision bug fix Disease Solo improved interface Echo improved new Code Example Line of Sight Example e engine fixes many extensions can now be used in saved applets however extensions that require additional external jars still don t work fixed bug in in radius where a large radius in a non wrapping world could give incorrect results fixed bug where calling movie close when no movie was open could cause NetLogo to hang fixed some error messages to more accurately report the location of the error e interface fixes when opening models from old NetLogo versions user choice is now auto translated to user one of in the 3D view patch and turtle labels are now positioned correctly even
194. g a number using scientific notation you must include the decimal point For example 1E8 will not be accepted Instead you must write 1 0E8 or 1 E8 O gt show 1 0E8 observer 1 0E8 O gt show 1 E8 observer 1 0E8 O gt show 1E8 ERROR Illegal number format When entering a number the letter E may be either upper or lowercase When printing a number NetLogo always uses an uppercase E O gt show 4 5e10 observer 4 5E10 Floating point accuracy When using floating point numbers you should be aware that due to the limitations of the binary representation for floating point numbers you may get answers that are slightly inaccurate For example O gt show 0 1 0 1 0 1 observer 0 30000000000000004 O gt show cos 90 observer 6 123233995736766E 17 This is an inherent issue with floating point arithmetic it occurs in all programming languages that support floating point If you are dealing with fixed precision quantities for example dollars and cents a common technique is to use only integers cents internally then divide by 100 to get a result in dollars for display If you must use floating point numbers then in some situations you may need to replace a straightforward equality test suchas if x 1 with a test that tolerates slight imprecision for example if abs x 1 lt 0 0001 Also the precision primitive is handy for rounding off numbers for display purposes NetLogo mon
195. g that is going on in the world For a detailed description and specifics about this world refer to the_NetLogo Programming Guide In the Command Center we have the ability to give the observer a command the turtles a command or the patches a command We choose between these options by using the popup menu located in the bottom left corner of the Command Center You can also use the tab key on your keyboard to cycle through the different options e In the Command Center click on the observer gt in the bottom left corner Command Center Wi Clear observer gt ask patches set pcolor yellow observer gt ask turtles set color brown obsepar v observer j patches e Ta Key Tutorial 2 Commands 39 NetLogo 3 1 4 User Manual e Choose turtles from the popup menu e Type set color pink and press return e Press the tab key until you see patches gt in the bottom left corner e Type set pcolor white and press return What does the View look like now Do you notice any differences between these two commands and the observer commands from earlier The observer oversees the world and therefore can give a command to the patches or turtles using ask Like in the first example observer gt ask patches set pcolor yellow the observer has to ask the patches to set their pcolor to yellow But when a command is directly given to a group of agents like in the second example patches gt set pcolor whi
196. ge Reports true if a new computer client just entered the simulation Reports false otherwise hubnet exit message Reports true if a new computer client just exited the simulation Reports false otherwise For both hubnet enter message and hubnet exit message hubnet message source will contain the user name of the client that just logged on or off Also if hubnet message and hubnet message tag are used while hubnet enter message Or hubnet exit message are true a Runtime Error will be given Generally part of your go procedure will include checking for waiting messages and handling them to listen clients while hubnet message waiting 142 HubNet Authoring Guide NetLogo 3 1 4 User Manual hubnet fetch messag ifelse hubnet enter message create new student ifelse hubnet exit message remove student execute command hubnet message tag end Sending data It is also possible to send data from NetLogo to the clients For Calculator HubNet NetLogo sends the data to the Navigator server and then the calculators can then access it For Computer HubNet NetLogo is able to send the data directly to the clients The primitives for sending data to the server are hubnet broadcast tag name value This broadcasts value from NetLogo to the variable in the case of Calculator HubNet or interface element in the case of Computer HubNet with the name tag name to all the client
197. gents and can be used anywhere in a model Most often globals is used to define variables or constants that need to be used in many parts of the program H hatch hatch lt breeds gt 220 Primitives Dictionary NetLogo 3 1 4 User Manual hatch number commands hatch lt breeds gt number commands This turtle creates number new turtles each identical to its parent and asks the new turtles to run commands You can use the commands to give the new turtles different colors headings or whatever The new turtles are created all at once then run one at a time in random order If the hatch lt breeds gt form is used the new turtles are created as members of the given breed Otherwise the new turtles are the same breed as their parent Note While the commands are running no other agents are allowed to run any code as with the without interruption command This ensures that the new turtles cannot interact with any other agents until they are fully initialized In addition no display updates take place until the commands are done This ensures that the new turtles are never drawn in an partly initialized state hatch 1 1t 45 fd 1 7 this turtle creates one new turtle 7 and the child turns and moves away hatch sheep 1 set color black this turtle creates a new turtle 7 Of the sheep breed heading heading x This is a built in turtle variable It indicates the direction the turtle is facing Th
198. ght in a simulated city The class as a whole tries to make traffic flow efficiently through the city As the simulation runs data is collected which can afterwards be analyzed on a computer or calculator For more information on participatory simulations and their learning potential please visit the Participatory Simulations Project web site Understanding HubNet NetLogo NetLogo is a programmable modeling environment It comes with a large library of existing simulations both participatory and traditional that you can use and modify Content areas include social science and economics biology and medicine physics and chemistry and mathematics and computer science You and your students can also use it to build your own simulations For more about NetLogo see the NetLogo Users Manual In traditional NetLogo simulations the simulation runs according to rules that the simulation author specifies HubNet adds a new dimension to NetLogo by letting simulations run not just according to rules but by direct human participation Since HubNet builds upon NetLogo we recommend that before trying HubNet for the first time you become familiar with the basics of NetLogo To get started using NetLogo models see_Tutorial 1 Running Models in the NetLogo Users Manual HubNet Architecture HubNet simulations are based on a client server architecture The activity leader uses the NetLogo application to run a HubNet activity When NetLogo is running
199. gt The second line must be included exactly as shown In the first line you may specify a different encoding than us ascii such as UTF 8 but NetLogo doesn t support non ASCII characters in most situations so specifying a different encoding may be pointless Controlling API If BehaviorSpace is not sufficient for your needs a possible alternative is to use our Controlling API which lets you write Java code that controls NetLogo The API lets you run BehaviorSpace experiments from Java code or you can write custom code that controls NetLogo more directly to do BehaviorSpace like things See the Controlling section of the User Manual for further details on both possibilities Conclusion BehaviorSpace is still under development We d like to hear from you about what what additional features would be useful to you in your work Please write us at feedback ccl northwestern edu 134 BehaviorSpace Guide HubNet Guide This section of the User Manual introduces the HubNet system and includes instructions to set up and run a HubNet activity HubNet is a technology that lets you use NetLogo to run participatory simulations in the classroom In a participatory simulation a whole class takes part in enacting the behavior of a system as each student controls a part of the system by using an individual device such as a networked computer or TI 83 calculator For example in the Gridlock simulation each student controls a traffic li
200. h heading2 could be rotated to produce heading1 A positive answer means a clockwise rotation a negative answer counterclockwise The result is always in the range 180 to 180 but is never exactly 180 Note that simply subtracting the two headings using the minus operator wouldn t work Just subtracting corresponds to always rotating clockwise from heading2 to heading1 but sometimes the counterclockwise rotation is shorter For example the difference between 5 degrees and 355 degrees is 10 degrees not 350 degrees Primitives Dictionary 281 NetLogo 3 1 4 User Manual how subtract headings 80 60 gt 20 how subtract headings 60 80 gt 20 how subtract headings 5 355 gt 10 how subtract headings 355 5 gt 10 how subtract headings 180 0 gt 180 how subtract headings 0 180 gt 180 o lo o tila i wv i a sum sum list Reports the sum of the items in the list show sum values from turtles energy 7 prints the total of the variable energy 7 from all the turtles T tan tan number Reports the tangent of the given angle Assumes the angle is given in degrees _ tie tie leaf turtle root turtle Connects leaf turtle to root turtle so that the movement of the root turtle affects the location and heading of the eaf turtle When the root turtle moves the leaf turtles moves the same distance in the same direction The heading of the leaf turtle is not affected This works with forward jump and se
201. h the mean and in the case of the normal distribution the standard deviation random exponential reports an exponentially distributed random floating point number random gamma reports a gamma distributed random floating point number as controlled by the floating point alpha and lambda parameters Both inputs must be greater than zero Note for results with a given mean and variance use inputs as follows alpha mean mean variance lambda 1 variance mean random normal reports a normally distributed random floating point number random poisson reports a Poisson distributed random integer show random exponential 2 7 prints an exponentially distributed random floating 7 point number with a mean of 2 show random normal 10 1 5 2 7 prints a normally distributed random floating point 7 number with a mean of 10 1 and a standard deviation te OL 2 show random poisson 3 4 7 prints a Poisson distributed random integer with a j mean of 3 4 random int or float random int or float number NOTE This primitive should not be used in new models It is included only for backwards compatibility with NetLogo 1 x It will not necessarily continue to be supported in future versions of NetLogo When a NetLogo 1 x model is read into NetLogo 2 0 or higher all uses of the random primitive are automatically converted to random int or float instead because the meaning of random has changed It used to sometimes return an int
202. han the original if the original image has a grayscale palette To work around this issue convert the image file to an RGB palette Windows only bugs e The User Manual item on the Help menu does not work on every machine Windows 98 and ME are most likely to be affected newer Windows versions less so e Drawing and then erasing a line in the drawing may not erase every pixel exactly e On some laptops the Procedures and Info tabs may become garbled when you scroll them To avoid this bug reduce the size of the NetLogo window and or reduce the color depth of your monitor e g change from 32 bit to 16 or 8 bit color This is a bug in Java itself not in NetLogo per se For technical details on the bug see http developer java sun com developer bugParade bugs 4763448 html free registration required NetLogo users are encouraged to visit that site and vote for Sun to fix this bug Macintosh only bugs e On Mac OS X 10 4 only the Copy View and Copy Interface items may not work the resulting image is distorted The workaround is to use the Export View and Export Interface items instead This issue will go away if you use Software Update to get the latest Java from Apple e When opening a model from the Finder by double clicking on it or dragging it onto the NetLogo icon if NetLogo is not already running then the model may or may not open the bug is intermittent If NetLogo is already running the model always opens
203. hat you are modeling Note that even with no wrap primitives it was very difficult to model cylinders since the no wrap primitives report the distance or heading when wrapping is not allowed in either direction You might have bugs in your model If you are using a combination of no wrap and wrap primitives either it doesn t matter for some reason or there is a bug in your model we found a few bugs in our models For example the Conductor model compared distance no wrap to distance to determine whether the next position is wrapped around the world in which case the electron exits the system This is a clever way to solve the problem but unfortunately it is flawed Electrons that wrap in the y direction were also exiting the system which is incorrect in this case The only correct way to exit is to reach the cathode at the left end of the wire If you remove no wrap commands the topology is no longer hard coded into the model so it s easier to test out your model on a different shape of world without a lot of extra coding you may have to add a few extra checks to go from torus to box this is explained more in depth in the How to convert section Note that though we ve removed the no wrap primitives from the dictionary they are still available for you to use we did this so that old models don t have to be changed in order to run How to convert your model When you first open up your model in 3 1 NetLogo will automatically change all cases of
204. he model that will use the extension At the top of the Procedures tab write extensions example jar Now you can use first n integers just like it was a built in NetLogo reporter For example select the Interface tab and type in the Command Center observer gt show first n integers 5 observer 0 1 2 3 4 Extension development tips Debugging extensions There are special NetLogo primitives to help you as you develop and debug your extension Like the extensions facility itself these are considered experimental and will be changed at a later date That s why they have underscores in their name eprint __dump extensions prints information about loaded extensions eprint __dump extension prims prints information about loaded extension primitives e reload extensions forces NetLogo to reload all extensions the next time you compile your model Without this command changes in your extension JAR will not take effect until you open a model or restart NetLogo Third party JARs If your extension depends on code stored in a separate JAR copy the extra JARs into the extensions directory of the NetLogo installation Whenever an extension is imported NetLogo makes all the JARs in this folder available to the extension If you plan to distribute your extension to other NetLogo users make sure to provide installation instructions that describe which files should be copied to their extensions directory Extensions Guide 153 N
205. he pen back down ppd for short If you want to plot individual points instead of lines or you want to draw bars instead of lines or points you need to change the plot pen s mode Three modes are available line bar and point Line is the default mode Normally you change a pen s mode by editing the plot This changes the pen s default mode It s also possible to change the pen s mode temporarily using the set p1ot pen mode command That command takes a number as input 0 for line 1 for bar 2 for point Histograms A histogram is a special kind of plot that measures how frequently certain values or values in certain ranges occur in a collection of numbers that arise in your model For example suppose the turtles in your model have an age variable You could create a histogram of the distribution of ages among your turtles with the histogram from command like this histogram from turtles age If the data you want to histogram don t come from an agentset but from a list of numbers use the histogram 1i st command instead Note that using the histogram commands doesn t automatically switch the current plot pen to bar mode If you want bars you have to set the plot pen to bar mode yourself As we said before you can change a pen s default mode by editing the plot in the Interface tab The width of the bars in a histogram is controlled by the plot pen s interval You can set a plot pen s default interval by editing the pl
206. he springs should push in both directions parallel to the magnetic field if it is true the networks will be more evenly spaced 120 Programming Guide NetLogo 3 1 4 User Manual Link Shape and Direction Indicators The default shape of all link turtles is link You can still set their shape using set shape newshape Or set default shape linkbreed newshape All directed links have a direction indicator shape link direction This shape will be drawn over top of the link turtle near the destination node lt will have the same color as the link turtle The shape will scale with the line thickness of the link turtle see __set line thickness with a minimum size of 1 You may edit the link and link direction shapes but they cannot be deleted If you wish to have no direction indicators remove all elements from the 1ink direction shape Code Examples Network Example Giant Component Small Worlds Preferential Attachment Tie Tie is an experimental part of NetLogo and primitives related to Tie are subject to change Because Tie is experimental the names of the primitives begin with two underscores Tie connects two turtles so that the movement of the root turtle affects the location and heading of the leaf turtle When the root turtle moves the leaf turtles moves the same distance in the same direction The heading of the leaf turtle is not affected This works with forward jump and setting the xcor or ycor
207. i return list e To access arguments use org nlogo api Argument s typesafe helper methods such Extensions Guide 151 NetLogo 3 1 4 User Manual as getIntegerValue e Throw org nlogo api ExtensionException to signal a NetLogo runtime error to the modeler A Command is just like a Reporter except that reporters implement Object report while commands implement void perform 2 Write a ClassManager Each extension must include in addition to any number of command and reporter classes a class that implements the interface org nlogo api ClassManager The ClassManager tells NetLogo which primitives are part of this extension In simple cases extend the abstract class org nlogo api DefaultClassManager which provides empty implementations of the methods from ClassManager that you aren t likely to need Here s the class manager for our example extension SampleExtension java import org nlogo api public class SampleExtension extends DefaultClassManager public void load PrimitiveManager primitiveManager primitiveManager addPrimitive first n integers new IntegerList addPrimitive tells NetLogo that our reporter exists and what its name is 3 Write a Manifest The extension must also include a manifest The manifest is a text file which tells NetLogo the name of the extension and the location of the ClassManager The manifest must contain three tags e Extens
208. iable in your model Elements of other colors don t change For example you could create cars that always have yellow headlights and black wheels but different body colors Shapes Editor Guide 125 NetLogo 3 1 4 User Manual Other buttons The Rotate Left and Rotate Right buttons rotate elements by 90 degrees The Flip Horizontal and Flip Vertical buttons reflect elements across the axes These four buttons will rotate or flip the entire shape unless an element is selected in which case only that element is affected These buttons are especially handy in conjunction with the Duplicate button if you want to make shapes that are symmetrical For example if you were making a butterfly you could draw the butterfly s left wing with the polygon tool then duplicate the wing with the Duplicate button then turn the copy into a right wing with the Flip Horizontal button Shape Design It s tempting to draw complicated interesting shapes but remember that in most models the patch size is so small that you won t be able to see very much detail Simple bold iconic shapes are usually best Keeping a Shape When the shape is done give it a name and press the Done button at the bottom of the editing window The shape and its name will now be included in the list of shapes along with the default shape Using Shapes in a Model In the model s code or in the command center you can use any of the shapes that are in the mod
209. ideas within this model Feel free to manipulate more than one variable at a time As you are testing your hypotheses you will notice that patterns are emerging from the data For example if you keep the number of people at the party constant but gradually increase the Sample Model Party 25 NetLogo 3 1 4 User Manual tolerance level more mixed groups appear How high does the tolerance value have to be before you get mixed groups What percent tolerance tends to produce what percentage of mixing Thinking With Models Using NetLogo to model situations like this party scenario allows you to experiment with a system in a rapid and flexible way that would be difficult to do in a real world situation Modeling also gives you the opportunity to observe a situation or circumstance with less prejudice as you can examine the underlying dynamics of a situation You may find that as you model more and more many of your preconceived ideas about various phenomena will be challenged For example a surprising result of the Party model is that even if tolerance is relatively high a great deal of separation between the sexes occurs This is a classic example of an emergent phenomenon where a group pattern results from the interaction of many individuals This idea of emergent phenomena can be applied to almost any subject What other emergent phenomena can you think of To see more examples and gain a deeper understanding of this concep
210. if the origin is off center 4 link direction indicators now show up in the 3D view and in HubNet view mirroring fixed bug where the Procedures tab could lose the keyboard focus when the compiler finds an error fixed bug where using the black arrows in the control strip to resize the world could cause an incorrect world size to appear in the strip fixed bug in BehaviorSpace where failure to create an output file caused an uninformative error message Version 3 1 April 14 2006 e system the 3D view now works on Intel based Macs for Windows users our bundled Java version is now 1 5 was 1 4 for Mac users Java 1 5 is now used if it is available e models new earth science model Grand Canyon new EvoLab evolution model Sunflower Biomorphs new social science model Ethnocentrism new mathematics model Voronoi new physics model DLA Simple new computer science models Perceptron Artificial Neural Network new biology system dynamics models Tabonuco Yagrumo Tabonuco Yagrumo Hybrid new code examples Moore amp Von Neumann Example Intersecting Lines Example Diffuse Off Edges Example Tie System Example improved ProbLab model Dice Stalagmite improved social science models Traffic Grid Scatter improved chemistry physics model GasLab Circular Particles runs faster improved networks models using experimental link primitives Giant Component Preferential Attachment Small Worlds e features 8 What
211. ii eer dire das ta tati a Sia TUE SE Sa 217 THOS SHOW sois nds etn ete dew Selene actos at dein ive A E ee Geen E E E A ana ae 217 MOP diia 217 TIO ITC casco de do A O E Ad A DO dita o 217 PUTS is cnt TN 218 MESA IN PEDRO NUDE A a oa Aoki PRE ok cache AN 218 A A tees et atone TA AD Sec aaah baat cde pa ra e JO Sate tat Na 218 A A ole ats sa 219 TONOWSING EE a te Comet ithe lage 219 foreach aire a ose RD ROO sek PDS DE acai eerie eal ae wee ae 219 ONAN E Ke tia Tia 220 A EE A A 220 E E E E A RN A RR E E ERR T AA EA 220 QIODAIS ii A A A O 220 A O 220 hatch hatch lt breeds gt ccc ccccccccccecceeececeeeeceeeeseneeeaneeceeceueenseseuneseeneeeennaseeneeeeneeeenneeeees 220 heading ON 221 aile o 5 PP eee gt IA US E EVA a ee JR RA 221 PUGS PUTS Enos eet vee Sache eae RR RR thet RR E RE A RR RR iets state 222 SOTANO MUS rasta teeta santa a esters seein Na 222 histogram IISL ss iaa daa 222 NOME A A A A AA A a 223 AS an 223 NUDE IEDTOLAACAS iii dida 223 MS A 223 hubnet emteremess ade iaa ita 224 MUBNEt EXit MESSAGE cirio cid o AA 224 hubbnet fetCh MeSSAGE ceccessnneecceeeeeeseseneeeeeeeeeeeeseeeeeeeeeeeeeesesneqnaeeeeeeesseeesesnseeeeeeees 224 MUDNET MESSACE iii dde 224 DUDNet MESSage SQUICB ccccccocccnncnnnnnnnononnnnnnnnnnnnn nono nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnrnnnninennss 224 DUDNet MESSage taQ cccccccccccconononononononononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnineninnenss 224 hubn
212. in whatever the current directory is This can be changed using the command set current directory It defaults to to the model s directory file open file open string This command will interpret string as a path name to a file and open the file You may then use the reporters file read file read line and file read characters to read in from the file or file write file print file type or file show to write out to the file Note that you can only open a file for reading or writing but not both The next file i o primitive you use after this command dictates which mode the file is opened in To switch modes you need to close the file using file close Also the file must already exist if opening a file in reading mode When opening a file in writing mode all new data will be appended to the end of the original file If there is no original file a new blank file will be created in its place You must have write permission in the file s directory If you don t want to append but want to replace the file s existing contents use file delete to delete it first perhaps inside a carefully if you re not sure whether it already exists Note that the string can either be a file name or an absolute file path If it is a file name it looks in whatever the current directory is This can be changed using the command_set current directory It is defaulted to the model s directory file open myfile in txt print file read line gt First
213. in Variables hind etna toned nad Rove Cn ase ss ee 193 viii NetLogo 3 1 4 User Manual Table of Contents Primitives Dictionary attoplOiAc e RR RD aeit 197 auto plot off AUTO PlOL ON sini ecacnaceesexeesisaseuerceacdverech ereto nude auddvantea sre detelsateabind dented 197 Bani BY um Bia dad set TN DA BARR AL AS DA o A AR A A a 198 EEE ia sta si nn as SOON TIA sa sted Seed sae seve bon ee ae oe ete vine etek io a Se Sie 198 OGD yin ts 198 POMENE cus duras a A ee 198 A O ATA 199 A O A 199 but first bf Dut last Dl o oononnoniincnnoniccinnancinncan cnc nica cnn arca aran 200 A TT 200 CAN MOVE 2 mid A a A fa A or ead 200 ANOLON O 201 COMING ssi AA AAA a nie aE 201 cearcal Ca oa o ees Wipe Sete hate at Sa ala dates cated adie oa amp Dim da ta Ui Ate 201 Clear all SlOt she ec A ss dadeanvebiedstdasssteudstiaasedes ouetes 201 clear draWingi Cd iii 201 Clears Ud AAA AAA ad 202 A O O 202 A AR 202 clear lUlES Cuil a A oh eth A A indi 202 CO NN A AA a ie oe EA ae 203 COS EEE o bet cadet A eet OG eee tee eee A 203 COUN cate indo an ae aa o ae do tda dea das a he end Ae a fea o da do ce EA ee aed er oe 203 create lt breed gt to _ create lt breed gt from create lt breed gt with 203 create lturiles crt create lt breeds gt teresa aereas eee nara nana 204 create custom turtles cct create custom lt breeds gt cct lt breeds gt 205 create tempor
214. in educational projects It was created by_Arnan Sipitakiat at the MIT Media Lab A GoGo Board has 8 sensor ports and 4 output ports and also a connector for add on boards such as a display or a wireless communication module Using the GoGo Board extension NetLogo models can interact with the physical world in two ways First it can gather data from the environment such as temperature ambient light or user input This information can be used by the model to change or calibrate its behavior Secondly it can control output devices NetLogo could control motors toys remote controlled cars electrical appliances light bulbs and automated laboratory equipment How to get a GoGo Board The GoGo Board is not a commercial product and thus cannot be bought at stores To get a GoGo Board you have to build one yourself or ask someone to do it for you The board was especially designed to be easy and cheap to build even if you don t have electronics skills The main resource about the GoGo Board is the web site www gogoboard org where you will find step by step instructions on how to buy components design the printed circuit board and assemble it The GoGo Board mailing list is gogoboard yahoogroups com Installing the GoGo Extension The GoGo Board needs to communicate with the computer in some way and to do so it uses the serial port The choice of this port instead of a USB port was motivated by the board s low cost principle the comp
215. ing a string with the file name and path relative to the model to the file which will serve as the client s interface This interface will be sent to any clients that log in hubnet set client interface COMPUTER clients Disease client nlogo when clients log in they will get the interface described in ti Disease client nlogo in the clients subdirectory of the model d This primitive must be called before you use any other HubNet primitives including hubnet reset so NetLogo knows which type of HubNet you are going to be using hubnet reset Starts up the HubNet system HubNet must be started to use any of the other HubNet primitives with the exception of hubnet set client interface HubNet remains running as long as this model is open it stops running when the model is closed or you quit NetLogo HubNet Authoring Guide 141 NetLogo 3 1 4 User Manual If you are using Computer HubNet you will be prompted for a session name This is an identifier to make servers discovered by the client uniquely identifiable These primitives are usually called from the startup procedure rather than setup of the NetLogo model since they should only be called once in a model Data extraction During the activity you will be transferring data between the HubNet clients and the server The following primitives allow you to extract data from the clients hubnet message waiting This looks for new information sent by the client
216. ing multiple instances of NetLogo though On Windows and Linux simply start the application again On a Mac you ll need to duplicate the application in the Finder then open the copy The copy takes up only a very small amount of additional disk space 180 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual Does NetLogo take advantage of multiple processors Nat for a single model run no The NetLogo engine is single threaded and we expect it to remain that way We don t have any plans to make it possible to split a single model run across multiple computers You can take advantage of multiple processors to do multiple model runs concurrently though in either of two ways e By having multiple copies of NetLogo open in separate Java virtual machines see this answer for instructions e By using BehaviorSpace or the Controlling API to do model runs from the command line In a future version of NetLogo we hope to improve the support for multiple processors as follows e Allow multiple models to be open simultaneously each running in a different thread and hence on a different processor e Modify BehaviorSpace to optionally do multiple model runs in parallel in a configurable number of separate threads so the runs would be spread across available processors Can distribute NetLogo model runs across a cluster of computers Many of the same comments in the previous answer apply It is not possible to split a single mode
217. ing patches nsum or 4 surrounding patches nsum4 Note that nsum nsum4 are equivalent to the combination of the sum values from and neighbors neighbors4 primitives sum values from neighbors var does the same thing as nsum var sum values from neighbors4 var does the same thing as nsum4 var Therefore nsum and nsum4 are included as separate primitives mainly for backwards compatibility with older versions of NetLogo which did not have the neighbors and neighbors4 primitives See also_neighbors neighbors4 O of VARIABLE of agent Reports the value of the VARIABLE of the given agent Can also be used to set the value of the variable show pxcor of one of patches 7 prints the value of a random patch s pxcor variable Primitives Dictionary 251 NetLogo 3 1 4 User Manual set color of one of turtles red 7 a randomly chosen turtle turns red ask turtles set pcolor of patch at 1 0 red 7 each turtle turns the patch on its left red one of one of agentset one of list From an agentset reports a random agent If the agentset is empty reports_nobody From a list reports a random list item It is an error for the list to be empty ask one of patches set pcolor green 77 a random patch turns green set pcolor of one of patches green 7 another way to say the same thing ask patches with any turtles here show one of turtles here 7 for each patch containing turtles prints one of
218. ion Name the name of the extension e Class Manager the fully qualified name of a class implementing org nlogo api ClassManager e Net Logo Version the version of NetLogo for which this JAR is intended If a version mismatch is detected when a JAR is imported a warning message will be issued and the user will have the opportunity to cancel If the user chooses to continue NetLogo will attempt to import the JAR anyway which of course may fail Here s a manifest for our example extension manifest txt anifest Version 1 0 Extension Name exampl Class Manager SampleExtension etLogo Version 3 1 4 The NetLogo Version line should match the actual version of NetLogo you are using Make sure even the last line ends with a newline character 152 Extensions Guide NetLogo 3 1 4 User Manual 4 Create a JAR To create an extension JAR first compile your classes as usual Make sure Net Logo jar from the NetLogo distribution is in your classpath For example javac classpath NetLogo jar IntegerList java SampleExtension java Then create a JAR containing the resulting class files and the manifest For example jar cvfm example jar manifest txt IntegerList class SampleExtension class For information about manifest files JAR files and Java tools see java sun com 5 Use your extension in a model To use our example extension put the extension JAR in the NetLogo extensions folder or in the same directory as t
219. is circle set default shape cats cat set default shape dogs dog create cats 1 7 new turtle s shape is cat ask cats set breed dogs 7 all cats become dogs and automatically 7 Change their shape to dog See also_shape 274 Primitives Dictionary NetLogo 3 1 4 User Manual set histogram num bars set histogram num bars integer Set the current plot pen s plot interval so that given the current x range for the plot there would be integer number of bars drawn if the histogram from or histogram list commands were called See also histogram from _ set line thickness _ set line thickness number Specifies the thickness of lines and outlined elements in the turtle s shape The default value is O This always produces lines one pixel thick Non zero values are interpreted as thickness in patches A thickness of 1 for example produces lines which appear one patch thick It s common to use a smaller value such as 0 5 or 0 2 Lines are always at least one pixel thick This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details Note that the command can be used with non link turtles too though set plot pen color set plot pen color number Sets the color of the current plot pen to number set plot pen interval set plot pen interval number Tells the current plot pen to move a distance of number in the x direction during each use of the p
220. is is a number greater than or equal to 0 and less than 360 0 is north 90 is east and so on You can set this variable to make a turtle turn See also_right left dx dy Example set heading 45 5 turtle is now facing northeast set heading heading 10 same effect as rt 10 hidden hidden x This is a built in turtle variable It holds a boolean true or false value indicating whether the turtle is currently hidden i e invisible You can set this variable to make a turtle disappear or reappear See also hide turtle show turtle Example set hidden not hidden Primitives Dictionary 221 NetLogo 3 1 4 User Manual 7 if turtle was showing it hides and if it was hiding 7 it reappears hide turtle ht hide turtle The turtle makes itself invisible Note This command is equivalent to setting the turtle variable hidden to true See also_show turtle histogram from histogram from agentset reporter Draws a histogram showing the frequency distribution of the values reported when all agents in the agentset run the given reporter The heights of the bars in the histogram represent the numbers of agents with values in those ranges Before the histogram is drawn first any previous points drawn by the current plot pen are removed The reporter should report a numeric value Any non numeric values reported are ignored The histogram is drawn on the current plot using the current plot pen and pen color
221. itable for controlling or scripting a NetLogo model but not ideal for embedding a NetLogo model in a larger application We also have a separate similar API which allows embedding only parts of NetLogo such as only the tabs not the whole window or only the contents of the Interface tab At present this additional API is not documented If you are interested in using it please contact us at feedback ccl northwestern edu Conclusion Don t forget to consult the NetLogo API Specification for full details on these classes and methods As mentioned before the controlling facility is considered experimental This initial API doesn t necessarily include everything you might expect Some facilities exist but are not yet documented So if you don t see the capability you want contact us we may be able to help you do you what you want Please do not hesitate to contact us at feedback ccl northwestern edu with questions as we may be able to find a workaround or provide additional guidance where our documentation is thin 158 Controlling Guide GoGo Extension What is the GoGo Board The GoGo Board extension lets you connect NetLogo to the physical world using sensors motors light bulbs LEDs relays and other devices The GoGo Extension for NetLogo provides primitives to communicate with a GoGo board via a serial interface A GoGo Board is an open source easy to build low cost general purpose board especially designed to be used
222. itional commands and reporters related to plotting Many of the Sample Models in the Models Library illustrate various advanced plotting techniques Also check out the following code examples Code Examples Plot Axis Example Plot Smoothing Example Strings To input a constant string in NetLogo surround it with double quotes 108 Programming Guide NetLogo 3 1 4 User Manual The empty string is written by putting nothing between the quotes like this Most of the list primitives work on strings as well butfirst string gt tring butlast string gt strin empty gt true empty string gt false first string gt s item 2 string gt r last string gt g length string gt 6 member s string gt true member rin string gt true member ron string gt false position s string gt 0 position rin string gt 2 position ron string gt false remove r string gt sting remove s strings gt tring replace item 3 string o gt strong reverse string gt gnirts A few primitives are specific to strings such as is string substring and word is string string gt true is string 37 gt false substring string 2 5 gt rin word tur tle gt turtle Strings can be compared using the lt gt lt and gt operators To concatenate strings that is combine them into a single string you can also
223. itives Dictionary NetLogo 3 1 4 User Manual On strings reports the position of the first appearance string1 as a substring of string2 or false if it does not appear Note The positions are numbered beginning with 0 not with 1 7 suppose mylist is 2 7 4 7 Bob show position 7 mylist gt 1 show position 10 mylist gt false show position rin string gt 2 See also_member precision precision number places Reports number rounded to places decimal places If places is negative the rounding takes place to the left of the decimal point show precision 1 23456789 3 gt 1 235 show precision 3834 3 gt 4000 print print value Prints value in the Command Center followed by a carriage return The calling agent is not printed before the value unlike_show See also_show type and_write See also output print pxcor pycor pxcor pycor El These are built in patch variables They hold the x and y coordinate of the patch They are always integers You cannot set these variables because patches don t move Primitives Dictionary 261 NetLogo 3 1 4 User Manual pxcor is greater than or equal to min pxcor and less than or equal to max pxcor similarly for pycor and min pycor and max pycor All patch variables can be directly accessed by any turtle standing on the patch See also_xcor _ycor random random number If number is positive reports a random integer greater than or eq
224. itors round the numbers they display to a configurable number of decimal places too Programming Guide 103 NetLogo 3 1 4 User Manual Random Numbers The random numbers used by NetLogo are what is called pseudo random This is typical in computer programming That means they appear random but are in fact generated by a deterministic process Deterministic means that you get the same results every time if you start with the same random seed We ll explain in a minute what we mean by seed In the context of scientific modeling pseudo random numbers are actually desirable That s because it s important that a scientific experiment be reproducible so anyone can try it themselves and get the same result that you got Since NetLogo uses pseudo random numbers the experiments that you do with it can be reproduced by others Here s how it works NetLogo s random number generator can be started with a certain seed value which can be any integer Once the generator has been seeded with the random seed command it always generates the same sequence of random numbers from then on For example if you run these commands random seed 137 show random 100 show random 100 show random 100 You will always get the numbers 95 7 and 54 Note however that you re only guaranteed to get those same numbers if you re using the same version of NetLogo Sometimes when we make a new version of NetLogo we change the random number generator
225. ive direction is not always how rounding is done in other software programs In particular it does not match the behavior of StarLogoT which always rounded numbers ending in 0 5 to the nearest even integer The rationale for this behavior is that it matches how turtle coordinates relate to patch coordinates in NetLogo For example if a turtle s xcor is 4 5 then it is on the boundary between a patch whose pxcor is 4 and a patch whose pxcor is 5 but the turtle must be considered to be in one patch or the other so the turtle is considered to be in the patch whose pxcor is 4 because we round towards the positive numbers show round 4 2 gt 4 show round 4 5 gt 5 show round 4 5 gt 4 run run string This agent interprets the given string as a sequence of one or more NetLogo commands and runs them The code runs in the agent s current context which means it has access to the values of local variables myself and so on See also_runresult runresult runresult string This agent interprets the given string as a NetLogo reporter and runs it reporting the result obtained The code runs in the agent s current context which means it has access to the values of local variables myself and so on See also_run S scale color scale color color number range1 range Reports a shade of color proportional to number Primitives Dictionary 271 NetLogo 3 1 4 User Manual If range7 is less than range2 then
226. l run across multiple computers but you can have each machine in a cluster doing one or more separate independent model runs using either BehaviorSpace or our Controlling API Numerous users are already using NetLogo on clusters You can seek them out on the NetLogo Users Group Can use max pxcor or max pycor etc as the minimum or maximum of a slider At present no In a future version of NetLogo we plan to support this Can change the choices in a chooser on the fly At present no In a future version of NetLogo we plan to support this Can divide the code for my model up into several files At present no In a future version of NetLogo we plan to support this How do show the legend in a plot Click the word Pens in the upper right corner of the plot The legend will include any pens that have the Show in Legend option checked when editing the plot Clicking Pens again will hide the legend FAQ Frequently Asked Questions 181 NetLogo 3 1 4 User Manual Why does my code have strange characters in it NetLogo only works in en locales A locale is a setting which tells NetLogo which language you are using as well as how to display dates and numbers You may need to switch to to an English locale before launching NetLogo This is usually done in the Regional Settings or Internationalization panel of the operating system In a future version of Netlogo we plan to support different languages and locales
227. l run Keeping track of how many times the go procedure is run is a useful way to cue these actions To keep track of this we will need to add a global variable e Change the first few lines of your procedures to include a new first line that declares a global variable globals ticks turtles own energy e Next change the setup procedure t setup clear all set ticks 0 Tutorial 3 Procedures 63 NetLogo 3 1 4 User Manual setup patches setup turtles do plots end e Finally change the go procedure CORGO Ae eleke 500 stoo I move turtles eat grass reproduce check death regrow grass do plot s set ticks ticks 1 end e Now setup and run the model The graph and model won t keep running forever They should stop automatically when the ticks counter reaches 500 How would you add a monitor to report the ticks How would you change your procedures so that the model stops when the ticks counter reaches 100 Some more details First instead of always using 100 turtles you can have a variable number of turtles e Make a slider variable called number using the monitor icon on the Toolbar and click on an open spot in the Interface Try changing the minimum and maximum values in the slider e Then inside of setup turt les instead of create turtles 100 you can type to setup turtles create turtles number ask turtles setxy random xcor random ycor end Test this change and compa
228. l stay at zero and max pxcor will set to 11 12 and 13 for each of the runs If neither of these conditions are true the origin is not centered nor at the edge of the world you cannot vary world height or wor1d width directly but you should vary max pxcor max pycor min pxcor and min pycor instead Varying random seed lets you repeat runs by using a known seed for the NetLogo random number generator Note that you re also free to use the random seed command in your experiment s setup commands For more information on random seeds see the Random Numbers section of the Programmer s Guide You may specify values either by listing the values you want used or by specifying that you want to try every value within a given range For example to give a slider named number every value from 100 to 1000 in increments of 50 you would enter numb ce PEO ORS OME OO ON Or to give it only the values of 100 200 400 and 800 you would enter number 100 200 400 800 Be careful with the brackets here Note that there are fewer square brackets in the second example Including or not including this extra set of brackets is how you tell BehaviorSpace whether you are listing individual values or specifying a range Also note that the double quotes around the variable names are required You can vary as many settings as you want including just one or none at all Any settings that you do not vary will retain their current values Not varying any s
229. lay back at 15 frames per second To make a movie with a different frame rate callmovie set frame rate with a different number of frames per second You must set the frame rate after movie start but before grabbing any frames To check the frame rate of your movie or to see how many frames you ve grabbed call movie status which reports a string that describes the state of the current movie To throw away a movie and delete the movie file call movie cancel NetLogo movies are exported as uncompressed QuickTime files To play a QuickTime movie you can use_QuickTime Player a free download from Apple Since the movies are not compressed they can take up a lot of disk space You will probably want to compress your movies with third party software The software may give you a choice of different kinds of compression Some kinds of compression are lossless while others are lossy Lossy means that in order to make the files smaller some of the detail in the movie is lost Depending on the nature of your model you may want to avoid using lossy compression for example if the view contains fine pixel level detail Code Example Movie Example Perspective The 2D and the 3D view show the world from the perspective of the observer By default the observer is looking down on the world from the positive z axis at the origin You can change the perspective of the observer by using the follow ride and watch observer commands and follow me ri
230. lculated from the origin 0 0 7 suppose I have 40 turtles at the origin show count turtles at 0 0 gt 40 If the name of a breed is substituted for turtles then only turtles of that breed are included breed cats cat breed dogs dog create custom dogs 5 setxy 2 3 show count dogs at 2 3 turtles from turtles from agentset reporter Reports a turtle agentset made by gathering together all the turtles reported by reporter for each agent in agentset For each agent the reporter must report a turtle agentset a single turtle or nobody turtles from patches one of turtles here 77 reports a turtle set containing one turtle from 7 each patch that has any turtles on it turtles from neighbors turtles here 5 if run by a turtle or patch reports the set of 5 all turtles on the neighboring eight patches note that 7 this could be written more concisely using turtles on 7 like this 237 turtles on neighbors See also patches from turtles on turtles here lt breed gt here turtles here lt breeds gt here Reports an agentset containing all the turtles on the caller s patch including the caller itself if it s a turtle ca crt 10 ask turtle 0 show count turtles here gt 10 Primitives Dictionary 285 NetLogo 3 1 4 User Manual If the name of a breed is substituted for turtles then only turtles of that breed are included breed cats cat breed dogs dog create cats
231. lding a model The entire set of procedures that was created above is shown below Appendix Complete code The complete model is also available in NetLogo s Models Library in the Code Examples section It s called Tutorial 3 Notice that this listing is full of comments which begin with semicolons Comments let you mix an explanation the code right in with the code itself You might use comments to help others understand your model or you might use them as notes to yourself In the Procedures tab comments are gray so your eyes can pick them out easily globals ticks 5 for keeping track of how many times the 77 go procedure has been run turtles own energy for keeping track of when the turtle is ready 7 to reproduce and when it will die to setup clear all set ticks 0 7 resets the counter to zero when setup is pressed setup patches setup turtles do plots end to setup patches ask patches set pcolor green end to setup turtles create turtles number uses the value of the number slider to create turtles ask turtles setxy random xcor random ycor end to go if ticks gt 500 stop 7 only run these procedures if ticks is less than 500 move turtles eat grass reproduce check death regrow grass do plots set ticks ticks 1 7 increase the tick counter by 1 each time through end to move turtles ask turtles set heading random 360 forward 1 set energy energy 1 when the turt
232. le moves it looses one unit of energy 66 Tutorial 3 Procedures NetLogo 3 1 4 User Manual end to eat grass ask turtles if pcolor green set pcolor black 7 the value of energy from grass slider is added to energy set energy energy energy from grass ifelse show energy set label energy the label is set to be the value of th nergy set label 7 the label is set to an empty text value end to reproduce ask turtles if energy gt birth energy set energy energy birth energy take away birth energy to give birth hatch 1 set energy birth energy give this birth energy to the offspring end to check death ask turtles if energy lt 0 die removes the turtle if it has no energy left end to regrow grass ask patches 3 out of 100 times the patch color is set to green if random 100 lt 3 set pcolor green end to do plots set current plot Totals which plot we want to use next set current plot pen turtles which pen we want to use next plot count turtles what will be plotted by the current pen set current plot pen grass which pen we want to use next plot count patches with pcolor green what will be plotted by the current pen end Tutorial 3 Procedures 67 68 NetLogo 3 1 4 User Manual Tutorial 3 Procedures Interface Guide This section of the manual walks you through every e
233. lement of the NetLogo interface in order and explains its function In NetLogo you have the choice of viewing models found in the Models Library adding to existing models or creating your own models The NetLogo interface was designed to meet all these needs The interface can be divided into two main parts NetLogo menus and the main NetLogo window The main window is divided into tabs e Menus e Tabs e Interface Tab Working with Interface Elements The 2D and 3D Views Command Center Plots e Procedures Tab e Information Tab Menus On Macs if you are running the NetLogo application the menubar is located at the top of the screen On other platforms the menubar is found at the top of the NetLogo window File Edit Tools Zoom Tabs Help NetLogo Untitled The functions available from the menus in the menubar are listed in the following chart Chart NetLogo Menus Save As Applet Used to save a web page in HTML format that has your model embedded in it as a Java applet Print Sends the contents of the currently showing tab to your printer poe ee all variables the current state of all turtles and patches he drawing and the output area to a file Export View Save a picture of the current view 2D or 3D to a file in PNG ormat Interface Guide 69 NetLogo 3 1 4 User Manual Export Interface Save a picture of the current Interface tab in PNG format Export Output Save the contents of the outp
234. licenses embedded in the source code files themselves In this license the Authors means the Copyright Holders listed above and the license itself is Copyright 2003 by Sean Luke The Authors hereby grant you a world wide royalty free non exclusive license subject to third party intellectual property claims to use reproduce modify display perform sublicense and distribute all or any portion of the source code or binary form of this software or related data with or without modifications or as part of a 4 Copyright Information NetLogo 3 1 4 User Manual larger work and under patents now or hereafter owned or controlled by the Authors to make have made use and sell Utilize all or any portion of the source code or binary form of this software or related data but solely to the extent that any such patent is reasonably necessary to enable you to Utilize all or any portion of the source code or binary form of this software or related data and not to any greater extent that may be necessary to Utilize further modifications or combinations In return you agree to the following conditions If you redistribute all or any portion of the source code of this software or related data it must retain the above copyright notice and this license and disclaimer If you redistribute all or any portion of this code in binary form you must include the above copyright notice and this license and disclaimer in the documentation and or other materia
235. links coming in from other nodes to the caller breed links link breed for network links to become friendly node procedure create links with other turtles show _ my links prints the agentset of link turtles that connecting with this node end This reporter is part of the experimental Links support in NetLogo See the_Links section of the Programming Guide for more details __my in lt breeds gt __my in lt breeds gt Reports an agentset of all the directed links coming in from other nodes to the caller breed links link breed for network links to become friendly node procedure create links to other turtles 246 Primitives Dictionary NetLogo 3 1 4 User Manual E show __my in links prints the agentset of link turtles that connect to this node end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details __ my out lt breeds gt __ my out lt breeds gt Reports an agentset of all the directed links going out from the caller to other nodes breed links link breed for network links to become friendly node procedure create links to other turtles show _ my out links prints the agentset of link turtles that connect from this node end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details m
236. lor plot plot number Increments the x value of the plot pen by plot pen interval then plots a point at the updated x value and a y value of number The first time the command is used on a plot the point plotted has an x value of 0 plot name plot name Reports the name of the current plot a string Primitives Dictionary 259 NetLogo 3 1 4 User Manual plot pen down ppd plot pen up ppu plot pen down plot pen up Puts down or up the current plot pen so that it draws or doesn t By default all pens are down initially plot pen reset plot pen reset Clears everything the current plot pen has drawn moves it to 0 0 and puts it down If the pen is a permanent pen the color and mode are reset to the default values from the plot Edit dialog plotxy plotxy number1 number2 Moves the current plot pen to the point with coordinates number1 number2 If the pen is down a line bar or point will be drawn depending on the pen s mode plot x min plot x max plot y min plot y max plot x min plot x max plot y min plot y max Reports the minimum or maximum value on the x or y axis of the current plot These values can be set with the commands set plot x range and set plot y range Their default values are set from the plot Edit dialog position position item list position string1 string2 On a list reports the first position of tem in list or false if it does not appear 260 Prim
237. lot command The plot pen interval also affects the behavior of the histogram from and histogram list commands set plot pen mode set plot pen mode number Sets the mode the current plot pen draws in to number The allowed plot pen modes are e 0 line mode the plot pen draws a line connecting two points together Primitives Dictionary 275 NetLogo 3 1 4 User Manual e 1 bar mode the plot pen draws a bar of width plot pen interval with the point plotted as the upper or lower if you are plotting a negative number left corner of the bar e 2 point mode the plot pen draws a point at the point plotted Points are not connected The default mode for new pens is 0 line mode set plot x range set plot y range set plot x range min max set plot y range min max Sets the minimum and maximum values of the x or y axis of the current plot The change is temporary and is not saved with the model When the plot is cleared the ranges will revert to their default values as set in the plot s Edit dialog setxy setxy X y The turtle sets its x coordinate to x and its y coordinate to y Equivalent to set xcor x set ycor y except it happens in one time step instead of two If xor y is outside the world NetLogo will throw a runtime error setxy 0 0 7 turtle moves to the middle of the center patch setxy random xcor random ycor 7 turtle moves to a random point setxy random pxcor random pycor 7 turtle moves to the center o
238. ls provided with the distribution and must indicate the use of this software in a prominent publically accessible location of the larger work You must not use the Authors s names to endorse or promote products derived from this software without the specific prior written permission of the Authors THE SOFTWARE IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS NOR THEIR EMPLOYERS NOR GEORGE MASON UNIVERSITY BE LIABLE FOR ANY CLAIM DAMAGES OR OTHER LIABILITY WHETHER IN AN ACTION OF CONTRACT TORT OR OTHERWISE ARISING FROM OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE For movie making NetLogo uses code adapted from JpeglmagesToMovie java by Sun Microsystems The copyright for that code is as follows Copyright c 1999 2001 Sun Microsystems Inc All Rights Reserved Sun grants you Licensee a non exclusive royalty free license to use modify and redistribute this software in source and binary code form provided that i this copyright notice and license appear on all copies of the software and ii Licensee does not utilize the software in a manner which is disparaging to Sun This software is provided AS IS without a warranty of any kind ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTI
239. m In NetLogo the number of tiles from right to left is called world width And the number of tiles from top to bottom is world height These numbers are defined by top bottom left and right boundaries 0 0 Screen Edge X Screen Edge X 34 Tutorial 1 Models NetLogo 3 1 4 User Manual Scieen Edge Y 0 0 Screen Edge Y In these diagrams max pxcor is 3 min pxcor is 3 max pycor is 2 and min pycor is 2 When you change the patch size the number of patches tiles doesn t change the patches only get larger or smaller on the screen Let s look at the effect of changing the minimum and maximum coordinates in the world e Using the Edit dialog that is still open change max pxcor to 30 and max pycor value to 10 Notice that min pxcor and min pycor change too That s because by default the origin 0 0 is in the center of the world What happened to the shape of the view e Press the setup button Now you can see the new patches you have created e Edit the view again e Change the patch size to 20 and press OK What happened to the size of the view Did its shape change Editing the view also lets you change other settings including the font size of labels and whether the view uses shapes Feel free to experiment with these and other settings as well Once you are done exploring the Wolf Sheep Predation model you may want to take some time just to explore some of the other models availa
240. m xcor random ycor right rt self set default shape set line thickness setxy shapes show turtle st sprout sprout lt breeds gt stamp stamp erase subject subtract headings tie towards towardsxy turtle turtles turtles at turtles from turtles here turtles on turtles own untie uphill value from Patch related primitives clear patches cp diffuse diffuse4 distance distancexy import pcolors inspect is patch myself neighbors neighbors4 nobody nsum nsum4 of patch patch at patch ahead patch at heading and distance patch here patch left and ahead patch right and ahead patches patches from patches own random pxcor random pycor self sprout sprout lt breeds gt subject value from Agentset primitives any ask at points lt breeds gt at lt breeds gt here lt breeds gt on count histogram from in cone n of neighbors neighbors4 one of other turtles hare other lt breeds gt here patches patches from 2a sort by turtles with with max with min turtles at turtles from turtles here turtles on values from Primitives Dictionary 191 NetLogo 3 1 4 User Manual Color primitives color extract hsb extract rgb hsb import pcolors pcolor rgb scale color shade of wrap color Control flow and logic primitives and carefully end error message foreach if ifelse ifelse value let loop map not or repeat report run runresult semicolon set stop startup to to report wait while without interr
241. max 10 0 Y Autoplot Plot Pens Choose Pen to Edit default 9 Rename Delete Create Color black H Mode Line B Interval 1 0 M Show in Legend Custom Color Many of the fields are fairly self explanatory the name of the plot labels for the x and y axes and ranges for the axes If Autoplot is checked the x and y changes will automatically readjust as points are added to the plot if they are outside the current range In the plot pens section of the dialog you can create and customize different pens in this plot You must always have a least one pen in every plot You start out with one named default you probably want to rename it something that is meaningful in the model All the items in the box below the pen name are settings relevant to that particular pen e Set the color to one of the NetLogo base hues or a custom color using the color swatches e Mode allows you to change the appearance of the plot pen line bar like a bar chart or point like line except the points are not connected e Interval is the amount by which x advances every time you use plot y e If the Show in Legend checkbox is checked the selected pen will be a part of the legend in the upper right hand corner of the plot which can be revealed by clicking on the word Pens on the plot itself For more detailed information on how each of these features works you can see the Plotting Section of the Programming Guide I
242. mber export view export interface export output export plot export all plots export world export view filename export interface filename export output filename export plot plotname filename export all plots filename export world filename Primitives Dictionary 211 NetLogo 3 1 4 User Manual export view writes the current contents of the current view to an external file given by the string filename The file is saved in PNG Portable Network Graphics format so it is recommended to supply a filename ending in png export interface is similar but for the whole interface tab export output writes the contents of the model s output area to an external file given by the string filename If the model does not have a separate output area the output portion of the Command Center is used export plot writes the x and y values of all points plotted by all the plot pens in the plot given by the string plotname to an external file given by the string filename If a pen is in bar mode mode 0 and the y value of the point plotted is greater than 0 the upper left corner point of the bar will be exported If the y value is less than 0 then the lower left corner point of the bar will be exported export all plots writes every plot in the current model to an external file given by the string filename Each plot is identical in format to the output of export plot export world writes the values of all variables both built in and use
243. mber in the range from 0 to 10 Choices are listed in the table below 234 Primitives Dictionary NetLogo 3 1 4 User Manual pa AS SOUTHEAST 4 a CAN SSSSSSSCSCSSCC r sommes OOOO ws o TAN CONCENTRIC 10 Magnetic field runs clockwise around the origin in concentric circles If bidirectional is true then links try to align with the magnetic field by pushing attached turtles both in the direction of the field and in the opposite direction Otherwise the links just push in a single direction breed links link breed nodes node to make a tree set default shape nodes circle create custom nodes 5 ask turtle 0 create link with turtle 1 create link with turtle 2 ask turtle 1 create link with turtle 3 create link with turtle 4 one turtle the root of the tree is our anchor set let anchor set turtles with who 0 layout with a fairly strong SOUTH magnetic field repeat 50 __layout magspring nodes anchor set 0 3 4 1 0 50 5 false end This command is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details __layout radial Primitives Dictionary 235 NetLogo 3 1 4 User Manual _ layout radial agentset root agent breed Arranges the agentset of turtles agentset in a radial tree layout centered around root agent Only links of the given breed will be used to determine the layout
244. ments Reports a list of the names of the 128 instruments for use with play note play note later start note and stop note play drum play drum drum velocity Plays a drum play drum ACOUSTIC SNARE 64 play note play note instrument keynumber velocity duration Plays a note for a specified duration in seconds The agent does not wait for the note to finish before continuing to next command 7 play a trumpet at middle C for two seconds play note TRUMPET 60 64 2 play note later play note later delay instrument keynumber velocity duration Waits for the specified delay before playing the note for a specified duration in seconds The agent does not wait for the note to finish before continuing to next command 7 in one seconds play a trumpet at middle C for two seconds play note later 1 TRUMPET 60 64 2 start note start note instrument keynumber velocity Starts a note The note will continue until stop note stop instrument or stop music is called 7 play a violin at middle C start note VIOLIN 60 64 7 play a C major scale on a xylophone foreach 60 62 64 65 67 69 71 72 start note XYLOPHONE 65 wait 0 2 stop note XYLOPHONE 166 Sound Extension NetLogo 3 1 4 User Manual stop note stop note instrument keynumber Stops a note 77 stop a violin note at middle C stop note VIOLIN 60 stop instrument stop instrument instrument Stops all notes of an i
245. mmetrical graphs and Programming Guide 119 NetLogo 3 1 4 User Manual give more space to branches that are wider layout radial also takes a breed as an input so you use one breed of links to layout the network and not another Given a set of anchor nodes __layout tutte places all the other nodes at the center of mass of the nodes it is linked to The anchorset is automatically arranged in a circle layout with a user defined radius and the other nodes will converge into place this of course means that you may have to run it several times before the layout is stable layout spring and __layout magspring are quite similar and are useful for many kinds of networks The drawback is that they are relatively slow since they take many iterations to converge In both layouts the links act as springs that pull the nodes they connect toward each other and the nodes repel each other In the magnetic spring there is also a magnetic field pulling the nodes in a compass direction you choose The strength of all of these forces are controlled by inputs to the primitives These inputs will always have a value between 0 and 1 keep in mind that very small changes can still affect the appearance of the network The springs also have a length in patch units however because of all the forces involved the nodes will not end up exactly that distance from each other The magnetic spring layout also has a boolean input bidirectional which indicates whether t
246. mple extensions sound jar speech jar Some extensions depend on additional files Check the instructions that come with the extension to see if you need to keep any other files with the extension Applets Models saved as applets using Save as Applet on NetLogo s File menu can make use of extensions However applets still cannot use extensions that require additional external jars We plan to fix this in a future release Writing Extensions We assume you have experience programming in Java Summary A NetLogo extension is a JAR that contains e one or more classes that implementation org nlogo api Primitive e a main class that implements org nlogo api ClassManager and e a NetLogo extension manifest file The manifest file must contain four tags e Manifest Version always 1 0 e Extension Name the name of the extension e Class Manager the fully qualified name of a class implementing org nlogo api ClassManager e Net Logo Version the version of NetLogo for which this JAR is intended If a user opens the extension with a different version of NetLogo a warning message is issued Tutorial Let s write an extension that provides a single reporter called first n integers first n integers will take a single numeric input n and report a list of the integers 0 through n 1 Of course you could easily do this just in NetLogo it s only an example 150 Extensions Guide 1 Write NetLogo 3 1 4 Use
247. mpty agentset The most straightforward way is n of 0 turtles or n of 0 patches Every agentset even an empty one is either a turtle set or a patch set FAQ Frequently Asked Questions 189 NetLogo 3 1 4 User Manual 190 FAQ Frequently Asked Questions Primitives Dictionary ABCDEFGHIJLMNOPRSTUVWXY Categories Turtle Patch Agentset Color Control Logic World Perspective Input Output Files List String Math Plotting Links Movie System HubNet Special Variables Keywords Constants Categories of Primitives This is an approximate grouping Remember that a turtle related primitive might still be called by patches or observers and vice versa To see which agent turtles patches observer can actually run each command consult each individual entry in the dictionary Turtle related back bk lt breeds gt at lt breeds gt here lt breeds gt on can move clear turtles ct create lt breeds gt create custom lt breeds gt create custom turtles cct create turtles crt die distance distancexy downhill downhill4 dx dy face facexy forward fd hatch hatch lt breeds gt hide turtle ht home inspect is lt breed gt is turtle jump left It myself nobody of other turtles here other lt breeds gt here paich ahead patch at heading and distance patch here patch left and ahead patch right and ahead pen down pd pen erase pe pen up pu rando
248. n The calculators are able to send and receive the following data types from NetLogo e Valid calculator lists such as 11 or PLOTS e Valid calculator matrices such as A or e Valid calculator strings such as Str1 or Str5 e Numbers such as A or B B The length of the list of numbers that a calculator sends depends on what information you want to send to the NetLogo model Further how those numbers are interpreted by the model is also up to you For more information on writing the calculator program portion of a HubNet Activity please_contact US Saving The data sent by calculators or NetLogo is saved in the order that the server receives the data 144 HubNet Authoring Guide NetLogo 3 1 4 User Manual Computer HubNet Information The following information is specific to Computer HubNet How To Make an Interface for a Client Open a new model in NetLogo Add any interface buttons sliders switches monitors plots choosers or text boxes that you want in the Interface Tab For buttons and monitors you only need to type a Display Name Any code you write in the Code or Reporter sections will be ignored The Display Name you give to the interface element is the tag that is returned by the hubnet message tag reporter in the NetLogo code For example if in the Interface Tab of the client interface you had a button called Move Left a slider called step size a switch called all in one step and
249. n for the product So for example NetLogo includes APIs so that NetLogo can be controlled from external Java code and users can write new commands and reporters in Java See Controlling and Extensions in the User Manual Do you offer any workshops or other training opportunities for NetLogo We offer workshops from time to time If a workshop has been scheduled we will announce it on the NetLogo home page and on the netlogo users group If interested in this type of opportunity please contact us at_feedback ccl northwestern edu What s the difference between StarLogo MacStarLogo StarLogoT and NetLogo The original StarLogo was developed at the MIT Media Lab in 1989 1990 and ran on a massively parallel supercomputer called the Connection Machine A few years later 1994 a simulated parallel version was developed for the Macintosh computer That version eventually became MacStarLogo StarLogoT 1997 developed at the Center for Connected Learning and Computer Based Modeling CCL is essentially an extended version of MacStarLogo with many additional features and capabilities Since then two multi platform Java based multi agent Logos have been developed NetLogo from the CCL and a Java based version of StarLogo from MIT The NetLogo language and environment differ in many respects from MIT StarLogo s Both languages were inspired by the original StarLogo but were redesigned in different ways NetLogo s design was driven by
250. n you re done adding segments double click After you draw a new element it is selected so you can move delete or reshape it if you want e To move it drag it with the mouse e To delete it press the Delete button e To reshape it drag the small handles that appear on the element only when it is selected e To change its color click on the new color Previews As you draw your shape you will also see it in five smaller sizes in the five preview areas found near the bottom of the editing window The previews show your shape as it might appear in your model including how it looks as it rotates The number below each preview is the size of the preview in pixels When you edit the view patch size is also measured in pixels So for example the preview with 20 below it shows you how your shape would look on a turtle of size 1 on patches of size 20 pixels The rotatable feature can be turned off if you want a shape that always faces the same way regardless of the turtle s heading Overlapping Shapes New elements go on top of previous elements You can change the layering order by selecting an element and then using the Bring to front and Send to back buttons Undo At any point you can use the Undo button to undo the edit you just performed Colors Elements whose color matches the Color that changes selected from a drop down menu the default is gray will change color according to the value of each turtle s color var
251. n your model Use the set command to set them If you don t set them they ll start out storing a value of zero Global variables can be read and set at any time by any agent As well a turtle can read and set patch variables of the patch it is standing on For example this code ask turtles set pcolor red causes every turtle to make the patch it is standing on red Because patch variables are shared by turtles in this way you can t have a turtle variable and a patch variable with the same name In other situations where you want an agent to read or set a different agent s variable you put of after the variable name and then specify which agent you mean Examples set color of turtle 5 red 5 turtle with ID number 5 turns red set pcolor of patch 2 3 green 7 patch with pxcor of 2 and pycor of 3 turns green ask turtles set pcolor of patch at 1 0 blue 7 every turtle turns the patch to its east blue ask patches with any turtles here set color of one of turtles here yellow 7 on every patch a random turtle turns yellow 88 Programming Guide Local variables A local variable is defined and used only in the context of a particular procedure or part of a procedure To create a local variable use the let command You can use this command NetLogo 3 1 4 User Manual anywhere If you use it at the top of a procedure the variable will exist throughout the procedure If you use it inside a set of square brackets fo
252. nce 90 1 green 7 turns the patch 1 to the west of the calling patch ja green See also patch patch at patch left and ahead patch right and ahead patch here patch here patch here reports the patch under the turtle Note that this reporter isn t available to a patch because a patch can just say self patch left and ahead patch right and ahead patch left and ahead angle distance patch right and ahead angle distance Reports the single patch that is the given distance from the calling turtle in the direction turned left 256 Primitives Dictionary NetLogo 3 1 4 User Manual or right the given angle in degrees from the turtle s current heading Reports nobody if the patch does not exist because it is outside the world If you want to find a patch in a given absolute heading rather than one relative to the current turtle s heading use patch at heading and distance instead set pcolor of patch right and ahead 30 1 green 7 the calling turtle looks 30 degrees right of its aie current heading at the patch 1 unit away and turns ioe that patch green note that this might be the same i patch the turtle is standing on See also patch patch at patch at heading and distance patches patches Reports the agentset consisting of all patches patches from patches from agentset reporter Reports a patch agentset made by gathering together all the patches reported by reporter for each agent in agen
253. nd Final commands These are any extra commands that you want run once when the run ends Usually this is left blank but you might use it to call the export world command or record the results of the run in some other way Time limit This lets you set a fixed maximum length for each run If you don t want to set any maximum but want the length of the runs to be controlled by the stop condition instead enter 0 130 BehaviorSpace Guide NetLogo 3 1 4 User Manual Running an experiment When you re done setting up your experiment press the OK button followed by the Run button You will be prompted to select the formats you would like the data from your experiment saved in Data is collected for each interval run or tick according to the setting of Measure runs at every tick option Table format lists each interval in a row with each metric in a separate column Table data is written to the output file as each run completes Table format is suitable for automated processing of the data such as importing into a database or a statistics package Spreadsheet format calculates the min mean max and final values for each metric and then lists each interval in a row with each metric in a separate column Spreadsheet data is more human readable than Table data especially if imported into a spreadsheet application Note however that spreadsheet data is not written to the results file until the experiment finishes Since spreadsheet d
254. nd Center you type plot 5 This will cause a message to be sent to all the clients telling them that they need to plot a point with a y value of 5 in the next position of the plot Notice if you are doing a lot of plotting all at once this can generate a lot of plotting messages to be sent to the clients If there is no plot with the exact same name in the clients or if the Mirror Plots on Clients checkbox in the HubNet Control Center is not checked then no plot updates are sent to the clients Clicking in the View on Clients If the View is included in the client it is possible for the client to send locations in the View to NetLogo by clicking in the client s View The tag reported by hubnet message tag for client clicks is the same as what is needed to send the View to a client the string View hubnet message reports a two item list with the x coordinate being the first item and the y coordinate being the second item So for example to turn any patch that was clicked on by the client red you would use the following NetLogo code if hubnet message tag View ask patches with pxcor pycor set pcolor red round item 0 hubnet message and round item 1 hubnet message Text Area for Input and Display A few models use an experimental interface element in the HubNet client that allows the modeler to display text on the client that can change throughout the run of the activity Further it can allow users to
255. nd extract hsb let you convert colors in the other direction Since the NetLogo color space doesn t include all hues hsb and rgb can t always give you the exact color you ask for but they try to come as close as possible Code Example You can use the HSB and RGB Example model to experiment with the HSB and RGB color systems Ask NetLogo uses the ask command to specify commands that are to be run by turtles or patches All code to be run by turtles must be located in a turtle context You can establish a turtle context in any of three ways e In a button by choosing Turtles from the popup menu Any code you put in the button will be run by all turtles e In the Command Center by choosing Turtles from the popup menu Any commands you enter will be run by all the turtles e By using ask turtles The same goes for patches and the observer except that code to be run by the observer must not be inside any ask Here s an example of the use of ask syntax in a NetLogo procedure to setup ca ert 100 create 100 turtles ask turtles set color red turn them red rt random float 360 77 give them random headings fa 50 7 spread them around Programming Guide 91 NetLogo 3 1 4 User Manual ask patches if pxcor gt 0 7 patches on the right side set pcolor green Of the view turn green end The models in the Models Library are full of other examples A good place to start looking is in the Code Examples
256. negative it turns right length length list length string Reports the number of items in the given list or the number of characters in the given string let let variable value Creates a new local variable and gives it the given value A local variable is one that exists only within the enclosing block of commands If you want to change the value afterwards use_set Example let prey one of sheep her if prey nobody ask prey die 238 Primitives Dictionary NetLogo 3 1 4 User Manual list list value value2 list value valuen Reports a list containing the given items The items can be of any type produced by any kind of reporter show list random 10 random 10 gt 4 9 or similar list show list 5 gt 5 show list random 10 1 2 3 random 10 gt 4 1 2 3 9 or similar list In In number Reports the natural logarithm of number that is the logarithm to the base e 2 71828 See also e log locals locals Vax1 var2 NOTE This keyword should not be used in new models Please use the let command instead locals is included only for backwards compatibility with NetLogo version 2 0 and earlier It will not necessarily continue to be supported in future versions of NetLogo Locals is a keyword used to declare local variables in a procedure that is variables that are usable only within that procedure It must appear at the beginning of the pro
257. nformation on using and editing plots in the Interface tab see the Interface Guide Specifying a plot If you only have one plot in your model then you can start plotting to it right away But if you have more than one plot you have to specify which one you want to plot to To do this use the set current plot command with the name of the plot enclosed in double quotes like this set current plot Distance vs Time You must supply the name of the plot exactly as you typed it when you created the plot Note that later if you change the name of the plot you ll also have to update the set current plot calls in your model to use the new name Copy and paste can be helpful here Programming Guide 105 NetLogo 3 1 4 User Manual Specifying a pen When you make a new plot it just has one pen in it If the current plot only has one plot pen then you can start plotting to it right away But you can also have multiple pens in a plot You can create additional pens by editing the plot and using the controls in the Plot Pens section at the bottom of the edit dialog Each pen should have a unique name You ll be using its name to refer to it in your code in the Procedures tab For a plot with multiple pens you have to specify which pen you want to plot with If you don t specify a pen plotting will take place with the first pen in the plot To plot with a different pen use the set current plot pen command with the name of the pen enclosed in d
258. ng and Computer Based Modeling Northwestern University Evanston IL HubNet Wilensky U amp Stroup W 1999 HubNet http ccl northwestern edu netlogo hubnet html Center for Connected Learning and Computer Based Modeling Northwestern University Evanston IL How do cite a model from the Models Library in a publication The proper citation is shown in the CREDITS AND REFERENCES section of each model s Info tab What license is NetLogo released under Are there are any legal restrictions on use redistribution etc The license is given in the Copyright section of the NetLogo User Manual as well as in the application s about box and the README file accompanying the download A quick summary of the license is that use is unrestricted including commercial use but there are some restrictions on redistribution and or modification unless you contact Uri Wilensky to arrange different terms We are in the process of reevaluating the language of the license in response to user feedback In the future we intend to send out a revised license Is the source code to NetLogo available At present no We are evaluating how best to distribute NetLogo when it is in a more mature state Making the source available is one possibility FAQ Frequently Asked Questions 173 NetLogo 3 1 4 User Manual We do understand however that it is important that NetLogo not be a closed and non extensible platform That is not our intentio
259. now that uses it may need changes in order to continue to work in future NetLogo versions e Note on memory Usage e Example with GUI e Example headless e BehaviorSpace e Other Options e Conclusion The NetLogo API Specification contains further details Note on memory usage In all of the examples below when invoking Java to run them you probably don t want to accept the default heap size settings Most Java VM s have a very small initial heap size and a small maximum heap size too When you run the NetLogo application it uses an initial heap size of 16 megabytes and a maximum heap size of 512 megabytes This is enough for most models Here s how to specify the heap sizes on the command line java server Dsun java2d noddraw true Xmsl6M Xmx512M Note that we recommend the server flag for best performance in most situations We also recommend setting the noddraw option to true when using the GUI as Direct Draw can conflict with OpenGL Example with GUI Here is a small but complete program that starts the full NetLogo application opens a model moves a slider sets the random seed runs the model for 50 ticks and then prints a result import org nlogo app App import java awt EventQueue public class Examplel public static void main String argv App main argv try EventQueue invokeAndWait new Runnable public void run Controlling Guide 155 NetLogo 3 1 4 User Manual
260. ns in population sizes There are two main variations to this model 82 Interface Guide NetLogo 3 1 4 User Manual You can edit the text in this view as in any text editor However a few different forms will be displayed specially when you switch out of the edit view Information Tab Markup Lines that come after blank lines and contain capital letters and no lower case el WHAT IS IT letters become section headers Any line that has only dashes is omitted Anything beginning with http becomes http ccl northwestern edu http ccl northwestern edu a Clickable hyperlink E mail addresses become clickable bugs ccl northwestern edu bugs ccl northwestern edu mailto links Lines that begin with the pipe shift backslash become monospaced text This is useful for diagrams and complicated formulas among other things this is preformatted text this is preformatted text you can put spacesin it you can put spaces in it To return to the normal view click the edit button Interface Guide 83 84 NetLogo 3 1 4 User Manual Interface Guide Programming Guide The following material explains some important features of programming in NetLogo The Code Example models mentioned throughout can be found in the Code Examples section of the Models Library e Agents e Procedures e Variables e Colors e Ask e Agentsets e Breeds e Synchronization e Buttons e Lists e Math e R
261. nstrument 7 stop all cello notes stop instrument CELLO stop music stop music Stops all notes Sound names Drums 35 Acoustic Bass Drum 59 Ride Cymbal 2 36 Bass Drum 1 60 Hi Bongo 37 Side Stick 61 Low Bongo 38 Acoustic Snare 62 Mute Hi Conga 39 Hand Clap 63 Open Hi Conga 40 Electric Snare 64 Low Conga 41 Low Floor Tom 65 Hi Timbale 42 Closed Hi Hat 66 Low Timbale 43 Hi Floor Tom 67 Hi Agogo 44 Pedal Hi Hat 68 Low Agogo 45 Low Tom 69 Cabasa 47 Open Hi Hat 70 Maracas 47 Low Mid Tom 71 Short Whistle 48 Hi Mid Tom 72 Long Whistle 49 Crash Cymbal 1 73 Short Guiro 50 Hi Tom 74 Long Guiro 51 Ride Cymbal 1 75 Claves 52 Chinese Cymbal 76 Hi Wood Block 53 Ride Bell 77 Low Wood Block 54 Tambourine 78 Mute Cuica 55 Splash Cymbal 79 Open Cuica 56 Cowbell 80 Mute Triangle 57 Crash Cymbal 2 81 Open Triangle 58 Vibraslap Sound Extension 167 Instruments Piano 1 Acoustic Grand Piano 2 Bright Acoustic Piano 3 Electric Grand Piano 4 Honky tonk Piano 5 Electric Piano 1 6 Electric Piano 2 7 Harpsichord 8 Clavi Chromatic Percussion 9 Celesta LO Glockenspiel L1 usic Box 12 Vibraphone 13 Marimba L4 Xylophone L5 Tubular Bells L6 Dulcimer Organ 17 Drawbar Organ 18 Percussive Organ 9 Rock Organ 20 Church Organ 21 Reed Organ 22 Accordion 23 Harmonica 24 Tango Accordion Guitar 25
262. nt NetLogo version the user is running On Macs this menu item is on the NetLogo menu instead User Manual Opens this manual in a web browser Tabs At the top of NetLogo s main window are three tabs labeled Interface Information and Procedures Only one tab at a time can be visible but you can switch between them by clicking on the tabs at the top of the window interface Information Procedures TEN 7 Chooser BS Monitor Vi plot Ed Output 5 Text a E 7 Taoa Pt E abe Button am Slider 8 Switch Right below the row of tabs is a toolbar containing a row of buttons The buttons available vary from tab to tab Interface Tab The Interface tab is where you watch your model run It also has tools you can use to inspect and alter what s going on inside the model When you first open NetLogo the Interface tab is empty except for the View where the turtles and patches appear and the Command Center which allows you to issue NetLogo commands Working with Interface Elements The toolbar on the Interface tab contains buttons that let you edit delete and create items in the Interface tab such as buttons and sliders Interface Guide 71 NetLogo 3 1 4 User Manual Chooser Em Monitor Plot FE Output Text f Edic Dele abe Button ot Slider 18 Switch So The buttons in the toolbar are described below
263. nterface Guide 79 NetLogo 3 1 4 User Manual Procedures Tab This tab is the workspace where the code for the model is stored Commands you only want to use immediately go in the Command Center commands you want to save and use later over and over again are found in the Procedures tab Interface Information Procedures es PLM MEETS Find Check blobals ticks breed sheep a sheep breed wolves wolf turtles own energy sheep own grabbed used to prevent two wolves from eating the same sheep patches own countdown to setup ca set ticks O ask patches set pcolor green if grass indicates whether the grass switch is on if it is true then grass grows and the sheep eat it if it false then the sheep don t need to eat ask patches set countdown random grass regrowth time initialize grass grow clocks randomly if random 2 O half the patches start out with grass set pcolor brown 4 To determine if the code has any errors you may press the Check button If there are any syntax errors the Procedures tab will turn red and the code that contains the error will be highlighted and a comment will appear in the top box Switching tabs also causes the code to be checked and any errors will be shown so if you switch tabs pressing the Check button first isn t necessary 80 Interface Guide NetLogo 3 1 4 User Manual Interface Information D Find A check
264. nth Strings 1 115 Steel Drums 52 Synth Strings 2 116 Woodblock 53 Choir Aahs 117 Taiko Drum 54 Voice Oohs 118 Melodic Tom 55 Synth Voice 119 Synth Drum 56 Orchestra Hit 120 Reverse Cymbal Brass Sound Effects 57 Trumpet 121 Guitar Fret Noise 58 Trombone 122 Breath Noise 59 Tuba 123 Seashore 60 Muted Trumpet 124 Bird Tweet 61 French Horn 125 Telephone Ring 62 Brass Section 126 Helicopter 63 Synth Brass 1 127 Applause 64 Synth Brass 2 128 Gunshot Sound Extension 169 NetLogo 3 1 4 User Manual 170 Sound Extension FAQ Frequently Asked Questions Feedback from users is very valuable to us in designing and improving NetLogo We d like to hear from you Please send comments suggestions and questions to feedback ccl northwestern edu and bug reports to bugs ccl northwestern edu Questions General e Why is it called NetLogo e What programming language was NetLogo written in e How do cite NetLogo in an academic publication e How do cite a model from the Models Library in an academic publication e What license is NetLogo released under Are there are any legal restrictions on use redistribution etc e Is the source code to NetLogo available e Do you offer any workshops or other training opportunities for NetLogo e What s the difference between StarLogo MacStarLogo StarLogoT and NetLogo e Has anyone built a model of lt x gt e Are NetLogo models runs scientifically reprod
265. ny questions about Computer HubNet or Calculator HubNet or need help getting started please email us at feedback ccl northwestern edu HubNet Guide 139 NetLogo 3 1 4 User Manual 140 HubNet Guide HubNet Authoring Guide This explains how to use NetLogo to modify the existing HubNet activities or build your own new HubNet activities e General HubNet Information e NetLogo Primitives Setup Data Extraction Sending Data e Calculator HubNet Information e Computer HubNet Information How To Make an Interface for a Client View Updates on the Clients Plot Updates on the Clients Clicking in the View on Clients Text Area for Input and Display General HubNet Information If you are interested in more general information on what HubNet is or how to run HubNet activities you should refer to the HubNet Guide NetLogo Primitives This section will introduce the set of primitives used to turn a NetLogo Model into a HubNet Activity These commands allow you to send data to and receive data from the clients Setup In order to make a NetLogo model into a HubNet Activity it is necessary to first indicate whether the clients are computers or calculators and then establish a connection between the server your computer and the clients the students calculators or computers using the following primitives hubnet set client interface client type client info If client type is COMPUTER client info is a list contain
266. o 3 1 4 User Manual mean list Reports the statistical mean of the numeric items in the given list Ignores non numeric items The mean is the average e the sum of the items divided by the total number of items show mean values from turtles xcor 7 prints the average of all the turtles x coordinates median median list Reports the statistical median of the numeric items of the given list Ignores non numeric items The median is the item that would be in the middle if all the items were arranged in order If two items would be in the middle the median is the average of the two show median values from turtles xcor 7 prints the median of all the turtles x coordinates member member value list member string1 string2 member agent agentset For a list reports true if the given value appears in the given list otherwise reports false For a string reports true or false depending on whether string1 appears anywhere inside string2 as a substring For an agentset reports true if the given agent is appears in the given agentset otherwise reports false how member 2 1 2 3 gt true how member 4 1 2 3 gt false how member rin string gt true how member turtle 0 turtles gt true how member turtle 0 patches gt false loo Il a n ll a n See also_position min min list Reports the minimum number value in the list It ignores other types of items 242 Primitives Di
267. o com group netlogo users message 2354 How can use different patch neighborhoods circular Von Neumann Moore etc The in radius primitives lets you access circular neighborhoods of any radius The neighbors primitive gives you a Moore neighborhood of radius 1 and the neighbors4 primitive gives you a Von Neumann neighborhood of radius 1 For Moore or Von Neumann neighborhoods of a larger radius see Moore amp Von Neumann Example in the Code Examples section of the Models Library Can connect turtles with lines to indicate connections between them Yes See the Links section of the Programming Guide How can I convert an agentset to a list of agents or vice versa If you want the list in a particular order use the sort or sort by primitives The Lists section of the Programming Guide explains how to do this If you want the list in a random order here s how values from lt agentset gt self Because all operations on agentsets are in random order the resulting list is in random order And here s how to convert a list of agents to an agentset turtles patches with member self lt list gt Note however that this method is not efficient and may slow down your model We hope to address this issue in a future version of NetLogo How does NetLogo decide when to switch from agent to agent when running code If you ask turtles or ask a whole breed the turtles are scheduled for execution in random order becau
268. ode hits the stop command or you press the button again to stop it If you stop the button the code doesn t get interrupted The button waits until the code has finished then pops up Normally a button is labeled with the code that it runs For example a button that says go on it usually contains the code go which means run the go procedure Procedures are defined in the Procedures tab see below But you can also edit a button and enter a display name for the button which is a text that appears on the button instead of the code You might use this feature if you think the actual code would be confusing to your users When you put code in a button you must also specify which agents you want to run that code You can choose to have the observer run the code or all turtles or all patches If you want the code to Programming Guide 95 NetLogo 3 1 4 User Manual be run by only some turtles or some patches you could make an observer button and then have the observer use the ask command to ask only some of the turtles or patches to do something When you edit a button you have the option to assign an action key This makes that key on the keyboard behave just like a button press If the button is a forever button it will stay down until the key is pressed again or the button is clicked Action keys are particularly useful for games or any model where rapid triggering of buttons is needed Buttons take turns More than one
269. oes not exist because it is outside the world set pcolor of patch ahead 1 green 7 turns the patch 1 in front of the calling turtle ae green note that this might be the same patch He the turtle is standing on See also patch at patch left and ahead patch right and ahead patch at heading and distance Primitives Dictionary 255 NetLogo 3 1 4 User Manual patch at patch at dx dy Reports the single patch at dx dy from the caller that is dx patches east and dy patches north of the caller If the caller is the observer the given offsets are computed from the origin Reports nobody if the patch does not exist because it is outside the world ask patch at 1 1 set pcolor green if caller is the observer turn the patch ii at 1 1 green 7 if caller is a turtle or patch turns the a patch just southeast of the caller green See also patch patch ahead patch left and ahead patch right and ahead patch at heading and distance patch at heading and distance patch at heading and distance heading distance st a patch at heading and distance reports the single patch that is the given distance from the calling turtle or patch along the given absolute heading In contrast to patch left and ahead and patch right and ahead the calling turtle s current heading is not taken into account Reports nobody if the patch does not exist because it is outside the world set pcolor of patch at heading and dista
270. of a slider 181 Can change the choices in a chooser on the fly ea 181 Can divide the code for my model up into several files 2 rea 181 How do show the legend in a plot occccccnnnnococnccccccnonnnononncncccnnnnnnnonnnnnnnnncnnnnnnnnnnnnos 181 Why does my code have strange Characters init eee 182 BENAVIOLS PACE io lat NAG SA 182 How do measure runs every NtiCkSB ccccccononococnncncccnnnnnonnnnnncnnnnnnnnnonnncnnnnnncnonnnnnnnnos 182 I m varying a global variable declared in the Procedures tab but it doesn t work a e e RS 182 PEO AMO A AA ie 182 How is the NetLogo language different from the StarLogoT language How do convert my StarLogoT model to NetLogo serena 182 How does the NetLogo language differ from other LOgoOsS cccccocnnoconcccccnonocononananonoss 183 My model from NetLogo 3 0 or earlier doesn t work or looks funny in 3 1 Help 184 Why do get a runtime error when use setxy random world width random world height It worked Defore occccccooooccccoconcccnnnononnnnoncccnnnnnononncnnnnnnnnnannnnennnnos 184 How do take the negative Of a nUMber occccooonococcccccccnnnonononnnncnnnnnnnononnncnnnnnncnnnnnnnnnnons 185 My turtle moved forward 1 but it s still on the same patch Why oocccccncccccoccccncccnanannns 185 patch ahead 1 is reporting the same patch my turtle is already standing on Why 185 How do give my turtle
271. of the root turtle When the root turtle turns right or left the leaf turtle is rotated around the root turtle the same amount The heading of the leaf turtle is also changed by the same amount Note that the movements of the root affect the leaf but not vice versa The leaf is free to move and turn on its own even while remaining tied and the root is not affected Programming Guide 121 NetLogo 3 1 4 User Manual The __ tie command connects a leaf turtle to a root turtle The __untie command removes the connection Code Example Tie System Example model shows turtles tied together including leaf turtles being the root of other leaf turtles 122 Programming Guide Shapes Editor Guide The Shapes Editor allows you to create and save turtle designs NetLogo uses fully scalable and rotatable vector shapes which means it lets you create designs by combining basic geometric elements which can appear on screen in any size or orientation Getting Started To begin making shapes choose Shapes Editor in the Tools menu A new window will open listing all the shapes currently in the model beginning with default the default shape The Shapes Editor allows you to edit shapes create new shapes and borrow shapes from a library or from another model Importing Shapes Every new model in NetLogo starts off containing a small core set of frequently used shapes Many more shapes are available by using the Import from library button
272. og to turn the updating off This will make the experiment go faster If you want to stop your experiment before it s finished press the Abort button But note that you ll lose any results that were generated up to that point When all the runs have finished the experiment is complete Advanced usage Running from the command line It is possible to run BehaviorSpace experiments headless that is from the command line without any graphical user interface GUI This is useful for automating runs on a single machine or a BehaviorSpace Guide 131 NetLogo 3 1 4 User Manual cluster of machines No Java programming is required Experiment setups can be created in the GUI and then run later from the command line or if you prefer you can create or edit experiment setups directly using XML It is easiest if you create your experiment setup ahead of time in the GUI so it is saved as part of the model To run an experiment setup saved in a model here is an example command line java server Xmsl16M Xmx512M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo xperiment experimentl After the named experiment has run the results are sent to standard output in spreadsheet format as CSV To change this see below When running the HeadlessWorkspace class as an application it forces the system property java awt headless to be true This tells Java to run in headless mode allowing NetLogo to run
273. ogo If your agents carry out a repetitive calculation on multiple variables it might be easier to have a list variable instead of multiple number variables Several primitives simplify the process of performing the same computation on each value in a list The Primitives Dictionary has a section that lists all of the list related primitives Constant lists You can make a list by simply putting the values you want in the list between brackets like this set mylist 2 4 6 8 Note that the individual values are separated by spaces You can make lists that contain numbers and strings this way as well as lists within lists for example 2 4 3 Sas The empty list is written by putting nothing between the brackets like this Building lists on the fly If you want to make a list in which the values are determined by reporters as opposed to being a series of constants use the List reporter The list reporter accepts two other reporters runs them and reports the results as a list If wanted a list to contain two random values might use the following code set random list list random 10 random 20 This will set random 1i st to a new list of two random integers each time it runs To make longer or shorter lists you can use the 1ist reporter with fewer or more than two inputs but in order to do so you must enclose the entire call in parentheses e g list random 10 list random 10 random 20 random 30 For more inform
274. older computers especially laptops have reported that entering fullscreen mode caused NetLogo to crash If you experience this problem please let us know Library Conflicts NetLogo includes JOGL version 1 1 0 for the 3D View On Mac OS X and Windows NetLogo uses the version of JOGL that comes with NetLogo even if you have a different version of JOGL on your computer If for some reason NetLogo is unable to find and use the correct version it will warn you If you get such a warning you may need to remove your separate JOGL installation in order for NetLogo s 3D View to work On a Linux machine if NetLogo is finding the wrong version of JOGL trying running with the Djava ext dirs command line option like this java Djava ext dirs jar NetLogo jar That should fix the problem If it doesn t try removing your JOGL installation Removing an old JOGL If NetLogo tells you you need to remove your JOGL installation here s how to do it You need to remove the jogl jar file and one or two native library files e Remove jogl jar from 1ib ext in your Java home directory e On Mac OS X remove liblog1 3nilib from Library Java Extensions or Library Java Extensions e On Windows remove 3og1 d11 and jog1_cg d11 from jre bin in your Java home e On Linux remove 1ibjog1 so from your always checked Java native libraries directory System Requirements 15 16 NetLogo 3 1 4 User Manual System Requirements Known
275. om manner Is there any type of pattern to this kind of grouping Let s take a closer look at this question by using the computer to model human behavior at a party NetLogo s Party model looks specifically at the question of grouping by gender at parties why do groups tend to form that are mostly men or mostly women Let s use NetLogo to explore this question What to do 1 Start NetLogo 2 Choose Models Library from the File menu NetLogo MIES Edit Tools Zoon 8 4 New N tl 3 Open O Models Library 3M t mi tet it B Deleg Save 36S Save AS Save As Applet Print dE P 3 Open the Social Science folder 4 Click on the model called Party Sample Model Party 23 NetLogo 3 1 4 User Manual 5 Press the open button 6 Wait for the model to finish loading 7 optional Make the NetLogo window bigger so you can see everything 8 Press the setup button In the view you will see pink and blue lines with numbers 10 15 13 12 18 14 15 18 17 These lines represent mingling groups at a party Men are represented in blue women in pink The numbers are the total number of people in each group Do all the groups have about the same number of people Do all the groups have about the same number of each sex Let s say you are having a party and invited 150 people You are wondering how people will gather together Suppose 10 groups form at the party How do you think they will g
276. on is pcolor green so that gives us just the green patches Now we have two monitors that will report how many turtles and green patches we have to help us track what s going on in our model As the model runs the numbers in the monitors will automatically change e Use the setup and go buttons and watch the numbers in the monitors change Switches and labels The turtles aren t just turning the patches black they re also gaining and losing energy As the model runs try using a turtle monitor to watch one turtle s energy go up and down It would be nicer if we could see every turtle s energy all the time We will now do exactly that and add a switch so we can turn the extra visual information on and off e To create a switch click on the switch icon on the Toolbar in the Interface tab and click on an open spot in the Interface A dialog box will appear e In the Global variable section of the dialog box type show energy Don t forget to include the question mark in the name See image below setup count turtles green patche 100 1225 Switch 800 FERA Global variable show energy Cancel 09 144 IE gt G08 Ei 30 e Now go back to the go procedure using the Procedures tab with the Toolbar e Rewrite the cat grass procedure as follows to cal grass ask turtles if pcolor green set pcolor black Tutorial 3 Procedures 57 NetLogo 3 1 4 User Manual
277. on of what s really going on with this checkbox To understand why this option is offered you need to understand a little about how NetLogo updates the view When something changes in the world for example if a turtle moves or a patch changes color the change does not always immediately become visible NetLogo would run too slowly if changes always immediately became visible So NetLogo waits until a certain amount of time has passed usually about 1 5 of a second and then redraws the view so that all the changes that have happened so far become visible This is sometimes called skipping frames by analogy with movies Skipping frames is good because each frame takes NetLogo time to draw so your model runs faster if NetLogo can skip some of them But skipping frames may be bad if the frames skipped contained information that you wanted to see Sometimes the way a model looks when frames are being skipped can be misleading 96 Programming Guide NetLogo 3 1 4 User Manual Even when the checkbox is on for a button NetLogo will still skip frames while the code in the button is running Checking the box only ensures that NetLogo will draw a frame when the code is done In some contexts you may want to force NetLogo to draw a frame even in the middle of button code To do that use the display command that forces NetLogo to refresh the view immediately In other contexts you may want to force NetLogo neverto draw a frame in the middle of
278. onents needed to build a USB compatible board would be more expensive If your computer does not have a serial port you need to purchase a USB to Serial adapter which can be easily found in computer stores with prices ranging from US 15 to US 30 if you have a Mac or Linux machine make sure the adapter is compatible with your platform To communicate with the GoGo Board through the serial port the GoGo Extension uses Sun Microsystems Java Communications API In each platform PC Mac Linux the procedures for installing the software needed to enable serial communication are slightly different Mac OS X There is no official implementation of the Java Communications API for OS X but the RXTX project provides an open source implementation You can download the RXTX installer for OS X from SourceForge Be sure to follow all the directions in the installer to create lock file directories and make sure your user is in the appropriate groups to use the lock files There are several commercial implementations of the Java Communications API for OS X which have not been tested with the GoGo extension but in theory should work Please contact us if you GoGo Extension 159 NetLogo 3 1 4 User Manual successfully use them or run into problems trying Windows Sun provides an implementation of the Java Communications API for Windows which you can download Once downloaded extract the files into a temporary directory Several files need
279. or the second items and so on All the lists must be the same length In commands use_ 1 through_ n to refer to the current item of each list Some examples make this clearer foreach 1 2 3 2 4 6 show the sum is 21 2 1 gt the sum is 3 gt the sum is 6 gt the sum is 9 foreach list turtle 1 turtle 2 3 4 ask 1 fd 2 7 turtle 1 moves forward 3 patches 7 turtle 2 moves forward 4 patches See also_map _ Primitives Dictionary 219 NetLogo 3 1 4 User Manual forward fd forward number The turtle moves forward by number steps If number is negative the turtle moves backward Turtles using this primitive can move a maximum of one unit per turn So fd 0 5 and fd 1 both take one turn but fd 3 takes three If the turtle cannot move forward number steps because it is not permitted by the current topology the turtle will complete as many steps of 1 as it can then stop See also jump can move fput fput item list Adds item to the beginning of a list and reports the new list 7 Suppose mylist is 5 7 10 set mylist fput 2 mylist 7 mylist is now 2 5 7 10 G globals globals var1 var2 This keyword like the breed lt breeds gt own patches own and turtles own keywords can only be used at the beginning of a program before any function definitions It defines new global variables Global variables are global because they are accessible by all a
280. ord Sensor sensor 7 will show the value of all sensors in the Command Center if sensor 1 lt 500 ask turtles fd 10 7 will move all turtles 10 steps forward if sensor 1 s value is less than 500 forever if sensor 1 lt 500 ask turtles fd 10 7 will continuously check sensor 1 s value and 7 move all turtles 10 steps forward every time 7 that the sensor value is less than 500 GoGo Extension 163 NetLogo 3 1 4 User Manual set output port power set output port power power level Sets the power level of the active output ports power level is a number between O off and 7 full power The output ports effected by those command are determined by the talk to output ports command Note that for many practical applications it is more efficient to use mechanical devices such as gears and pulleys to control the torque of motors Example talk to motors Tat Mb HEM gu set motor power 4 7 will lower the power of all output ports by half of the full power 164 GoGo Extension Sound Extension The Sound Extension for NetLogo provides primitives to add sound to NetLogo models The extension simulates a 128 key electronic keyboard with 47 drums and_128 melodic instruments as provided by General MIDI Level 1 specification It supports 15 polyphonic instrument channels and a single percussion channel Using more than 15 different melodic instruments simultaneously in a model will cause some sounds to
281. ored towards the end of the nlogo file in a section that begins and ends with a experiments tag Example lt experiments gt lt experiment name experiment repetitions 10 runMetricsEveryTick true gt lt setup gt setup lt setup gt lt go gt go lt go gt lt exitCondition gt not any fires lt exitCondition gt lt metric gt burned trees lt metric gt lt enumeratedValueSet variable density gt lt value value 40 gt lt value value 0 1 gt lt value value 70 gt lt enumeratedValueSet gt lt experiment gt lt experiments gt In this example only one experiment setup is given but you can put as many as you want between the beginning and ending experiments tags Between looking at the DTD and looking at examples you create in the GUI it will hopefully be apparent how to use the tags to specify different kind of experiments The DTD specifies which tags are required and which are optional which may be repeated and which may not and so forth When XML for experiment setups is included in a model file it does not begin with any XML headers because not the whole file is XML only part of it If you keep experiment setups in their own file separate from the model file then the extension on the file should be xml not nlogo and you ll need to begin the file with proper XML headers as follows lt xml version 1 0 encoding us ascii gt lt DOCTYPE experiments SYSTEM behaviorspace dtd
282. ormation Falo Marau ais gn Bic a A E E E E Ra 83 WHAT IS Esses sata Des trans ua A REED a TEL a Dou lapa A ea Ladies 83 PLOMO UI id O ASP RE R ERA OR 85 Agenissa A tastes PERSON aa ae a aa aeaaea 85 BLO caa E e EEEE RA AAA ea ae ee hot Bee ee 86 AY Fs iF fo sae aae oe AA e N lada ala ida eat aa cal da lema N 88 COM e e a te a a e O qua alo 89 A ld 91 AQGNISEtS cu AAA A A AAA A A 92 nn UPE RR A PP E ND nubian hace rae 94 BUTONS x tre Be AAD A O AA O O A a a 95 Syn hroniZa Nr dad 97 SS a A a at A EN 98 Mi a od o ean dm taal 102 Random NUMDETS A EE AE A nono ncnno nan E E A acena nana 104 Lules 105 PIO AA A ANA E 105 MOLINOS E A od 108 O A OA states 109 A E O NR 110 MOVIES a AA AS een Mla ee eae 111 POTS MO A A A daa 112 DAW ING a EEE AE E E tE 113 TODOIO oca 114 Pink A to Tc 118 MA A tl 121 Shapes Editor GUI aleeSatscs sos wnund cask cate aAA aAa t daw AA E Aa AAAA taaeaseateteeeaaas 123 Ge tting Started ta i n 123 Importing O aaa 123 Creating and Editing Shapes eres aaeaaaraaee re nanaaanaaaarereeaaaananna 124 A shel tea leet iM RD O DS E RR Si A tel A de SNIS EM ALE 125 Preview oxic r RR ARA ND oi tees ante RR RN A 125 Overlapping SAPOS its dado sio eb 125 AA A A A AR 125 CUM ll RR at 125 Other buttons aia AI A A A aided acess ede eee tees 126 Shape DOSIS a 126 REDDING A SHADE a A RS AA A RARO Reed 126 NetLogo 3 1 4 User Manual Table of Contents Shapes Editor Guide Using Shapes in a Modelacaniai
283. ort turtles and patches note that NetLogo adds import world though 18 Known Issues NetLogo 3 1 4 User Manual ebit bitand bitneg bitor bitset bitstring bitxor make bitarray rotate left rotate right shift left shift right e camera brightness camera click camera init camera set brightness enetlogo directory project directory project name project pathname save project Known Issues 19 20 NetLogo 3 1 4 User Manual Known Issues Contacting Us Feedback from users is very valuable to us in designing and improving NetLogo We d like to hear from you Web Site Our web site at_ccl northwestern edu includes our mailing address and phone number It also has information about our staff and our various research activities Feedback Questions Etc If you have general feedback suggestions or questions write to feedback ccl northwestern edu If you need help with your model you should also consider posting to the NetLogo users group at http groups yahoo com group netlogo users Reporting Bugs If you would like to report a bug that you find in NetLogo write to bugs ccl northwestern edu When submitting a bug report please try to include as much of the following information as possible e A complete description of the problem and how it occurred e The NetLogo model or code you are having trouble with If possible attach a complete model e Your system information NetLogo version OS ve
284. orts a string containing the current date and time The format is shown below All fields are fixed width so they are always at the same locations in the string The potential resolution of the clock is milliseconds Whether you get resolution that high in practice may vary from system to system depending on the capabilities of the underlying Java Virtual Machine show date and time gt 01 19 36 685 PM 19 Sep 2002 die die The turtle dies if xcor gt 20 die 7 all turtles with xcor greater than 20 die See also _ct diffuse diffuse patch variable number ig Tells each patch to share number 100 percent of the value of patch variable with its eight neighboring patches number should be between 0 and 1 Regardless of topology the sum of patch variable will be conserved across the world If a patch has fewer than eight neighbors the remainder stays on the patch at the edge of the world Note that this is an observer command only even though you might expect itto be a patch command The reason is that it acts on all the patches at once patch commands act on individual patches diffuse chemical 0 5 7 each patch diffuses 50 of its variable 7 Chemical to its neighboring 8 patches Thus 77 each patch gets 1 8 of 50 of the chemical from each neighboring patch 206 Primitives Dictionary NetLogo 3 1 4 User Manual diffuse4 diffuse4 patch variable number ig Like diffuse but only diffuses to the
285. ot in the Interface tab You can also change the interval temporarily with the set plot pen interval command or the set histogram num bars If you use the latter command NetLogo will set the interval appropriately so as to fit the specified number of bars within the plot s current x range Code Example Histogram Example Clearing and resetting You can clear the current plot with the clear plot command or clear every plot in your model with clear all plots The clear a11 command also clears all plots in addition to clearing everything else in your model If you only want to remove only the points that the current plot pen has drawn use plot pen reset When a whole plot is cleared or when a pen is reset that doesn t just remove the data that has been plotted It also restores the plot or pen to its default settings as they were specified in the Programming Guide 107 NetLogo 3 1 4 User Manual Interface tab when the plot was created or last edited Therefore the effects of such commands as set plot x range and set plot pen color are only temporary Autoplotting By default all NetLogo plots have the autoplotting feature enabled This means that if the model tries to plot a point which is outside the current displayed range the range of the plot will grow along one or both axes so that the new point is visible In the hope that the ranges won t have to change every time a new point is added when the ranges grow th
286. ou re done the dialog box closes Now you have a setup button Pressing the button runs a procedure called setup A procedure is a sequence of NetLogo commands that we assign a new name We haven t defined that procedure yet we will soon Because the button refers to a procedure that doesn t exist yet the button turns red Tutorial 3 Procedures 47 NetLogo 3 1 4 User Manual interface Information Procedures O Se ma da E SM E gt Edit Delete Button Slider Switch Chooser Monitor Plot Output Text noS IE gt eh sit 30 setup If you want to see the actual error message click the button Now we ll create the setup procedure so the error message will go away e Switch to the Procedures tab e Type the following EO Setup clear all create turtles 100 ask turtles setxy random xcor random ycor end When you re done the Procedures tab looks like this O 06 NetLogo Untitled Interface Information _ Procedures 9 Y Procedures w Find Check to setup clear all create turtles 100 ask turtles 1 setxy random xcor random ycor J end Note that the lines are indented different amounts Most people find it helpful to indent their code like this but it is not mandatory It makes the code easier to read and change Your procedure began with the word to and ended with the word end Every new procedure you create will begin and end with these two words
287. ouble quotes like this set current plot pen distance Plotting points The two basic commands for actually plotting things are plot and plotxy With plot you need only specify the y value you want plotted The x value will automatically be 0 for the first point you plot 1 for the second and so on That s if the plot pen s interval is the default value of 1 0 you can change the interval The plot command is especially handy when you want your model to plot a new point at every time step Example to setup plot count turtles end to go plot count turtles end Note that in this example we plot from both the setup and go procedures That s because we want our plot to include the initial state of the system We plot at the end of the go procedure not the beginning because we want the plot always to be up to date after the go button stops If you need to specify both the x and y values of the point you want plotted then use plot xy instead Code Example Plotting Example Other kinds of plots By default NetLogo plot pens plot in line mode so that the points you plot are connected by a line 106 Programming Guide NetLogo 3 1 4 User Manual If you want to move the pen without plotting you can use the plot pen up command ppu for short After this command is issued the plot and plot xy commands move the pen but do not actually draw anything Once the pen is where you want it use plot pen down to put t
288. p from basic geometric shapes squares circles and lines rather than a grid of pixels Vector shapes are fully scalable and rotatable NetLogo caches bitmap images of vector shapes size 1 1 5 and 2 in order to speed up execution A turtle s shape is stored in its shape variable and can be set using the set command New turtles have a shape of default The set default shape primitive is useful for changing the default turtle shape to a different shape or having a different default turtle shape for each breed of turtle The shapes primitive reports a list of currently available turtle shapes in the model This is useful if for example you want to assign a random shape to a turtle ask turtles set shape one of shapes Use the Shapes Editor to create your own turtle shapes or to add shapes to your model from our shapes library or to transfer shapes between models For more information see the Shapes Editor section of this manual The thickness of the lines used to draw the vector shapes can be controlled by the set line thickness primitive Code Examples Breeds and Shapes Example Shape Animation Example Plotting NetLogo s plotting features let you create plots to help you understand what s going on in your model Before you can plot you need to create one or more plots in the Interface tab Each plot should have a unique name You ll be using its name to refer to it in your code in the Procedures tab For more i
289. pcolor red 7 each turtle makes a red splotch of patches in a 60 degree cone of radius 3 ahead of itself in lt breed gt neighbor __in lt breed gt neighbor agent Reports true if there is a link going from agentto the caller to check friendship neighbors ca cct turtles 2 ask turtle 0 Primitives Dictionary 229 NetLogo 3 1 4 User Manual create link to turtle 1 show __in link neighbor turtle 1 prints false show __out link neighbor turtle 1 prints true ask turtle 1 show __in link neighbor turtle 0 j prints true show __out link neighbor turtle 0 prints false end This reporter is part of the experimental Links support in NetLogo See the_Links section of the Programming Guide for more details _ in lt breed gt neighbors __in lt breed gt neighbors Reports the agentset of all the node turtles that have links coming from them to the caller breed links link breed for network links to become friendly node procedure create links to friends show __out link neighbors prints the agentset of friends end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details __in lt breed gt from __in lt breed gt from agent Report the link turtle from the agent to the caller If no link exists then it reports nobody to find friendship with ca ect 2 ask tur
290. ple as possible so that it is easy to understand Eventually it will include many other things you want to have happen as the model runs such as calculating something or plotting the results Each of these things to do will have its own procedure and each procedure will have its own unique name The go button you made in the Interface tab is a forever button meaning that it will continually run its commands until you shut it off by clicking on it again After you have pressed setup once to create the turtles press the go button Watch what happens Turn it off and you ll see that all the turtles stop in their tracks Note that if a turtle moves off the edge of the world it wraps that is it appears on the other side This is the default behavior It can be changed see the_Topology section of the Programming Guide for more information Experimenting with commands We suggest you start experimenting with other turtle commands Type commands into the Command Center like turtles gt set color red or add commands to setup go Of move turtles Note that when you enter commands in the Command Center you must choose turtles gt patches gt Or observer gt in the popup menu on the left depending on which agents are going to Tutorial 3 Procedures 51 NetLogo 3 1 4 User Manual run the commands It s just like using ask turtles Or ask patches but saves typing You can also use the tab key to switch agent types which you
291. plotting work we ll need to create a plot in the Interface tab and set some settings in it Then we ll add one more procedure to the Procedures tab which will update the plot for us Let s do the Procedures tab part first 60 Tutorial 3 Procedures NetLogo 3 1 4 User Manual e Change setup to call the new procedure do plot s which we re about to add to setup clear all setup patches setup turtles do plots end e Also change go to call the do plots procedure LO go move turtles gat grass reproduce check death regrow grass do plots end e Now add the new procedure What we re plotting will be be the number of turtles and the number of green patches versus time At each time step a single run through the go procedure these values are added to the plot tordo plots set current plot Totals set current plot pen turtles plot count turtles set current plot pen grass plot count patches with pcolor green end Note that we use the p1ot command to add the next point to a plot However before doing that we need to tell NetLogo two things First we need to specify what plot we will be using since later our model might have more than one plot and second we need to specify which pen we want to plot with we will be using two pens on this plot The plot command moves the current plot pen to the point that has an X coordinate equal to 1 greater than the previously plotted X coordinate and a Y coordinate
292. pport will be enough without needing to use the API In some situations though you may want additional flexibility afforded by the API The HeadlessWorkspace has four methods for running experiments three variants of Controlling Guide 157 NetLogo 3 1 4 User Manual runExperiment plus runExperimentFromModel runExperimentFromModel is used when the experiment setup is already stored in the model file The two forms of runExperiment that take File arguments are used when the experiment setup is stored in a standalone XML file separate from the model file If the file contains only one setup you only need to pass in the File object If the file contains multiple setups you must also pass in a String Object holding the experiment name The form of runExperiment that takes only a String argument and an argument to specify the output format is used to pass the XML for the experiment setup directly All of these methods take a PrintWriter as a destination for the results If you just want to send them to standard output you can pass new java io PrintWriter System out The BehaviorSpace Guide explains how to specify experiment setups in XML The NetLogo API Specification contains further details on the HeadlessWorkspace class and its methods Other Options When your program controls NetLogo using the App class the entire NetLogo application is present including tabs menubar and so forth This arrangement is su
293. procedures e Control structures such as if and while are special forms not ordinary functions You can t define your own special forms so you can t define your own control structures NetLogo s run command is no help here FAQ Frequently Asked Questions 183 NetLogo 3 1 4 User Manual e As in most Logos functions as values are not supported Most Logos provide similar if less general functionality though by allowing passing and manipulation of fragments of source code in list form NetLogo s capabilities in this area are presently limited A few of our built in special forms use UCBLogo style templates to accomplish a similar purpose for example sort by length 21 lt length 22 string list In some circumstances using run and runresult instead is workable but unlike most Logos they operate on strings not lists Of course the NetLogo language also contains many additional features not found in most other Logos most importantly agents and agentsets My model from NetLogo 3 0 or earlier doesn t work or looks funny in 3 1 Help Here are short discussions of the issues that are likeliest to arise with links to further information If you are seeing pieces of turtle shapes wrapping around the view edges it s because NetLogo 3 0 allowed you to turn off such wrapping in the view without affecting the behavior of the model In NetLogo 3 1 if you don t want the view to wrap you must make it so the world doesn t wrap using 3
294. r __ lt breed gt neighbor agent k Reports true if there is a link going from agent to the caller or from the caller to agent to check friendship neighbors ca cct turtles 2 ask turtle 0 create link to turtle 1 show __in link neighbor turtle 1 prints false show __out link neighbor turtle 1 prints true show __link neighbor turtle 1 j prints true ask turtle 1 show __in link neighbor turtle 0 prints true show __out link neighbor turtle 0 prints false show __link neighbor turtle 0 prints true end This reporter is part of the experimental Links support in NetLogo See the_Links section of the Programming Guide for more details Primitives Dictionary 249 NetLogo 3 1 4 User Manual netlogo version netlogo version Reports a string containing the version number of the NetLogo you are running show netlogo version gt 3 1 4 new seed new seed Reports a number suitable for seeding the random number generator The numbers reported by new seed are based on the current date and time in milliseconds and lie in the range 2147483648 to 2147483647 new seed never reports the same number twice in succession This is accomplished by waiting a millisecond if the seed for the current millisecond was already used See also random seed no display no display Turns off all updates to the current view until the display command is issued This has two major uses One
295. r show abs 7 gt 7 show abs 5 gt 5 acos acos number Reports the arc cosine inverse cosine of the given number The input must be in the range 1 0 to 1 0 The result is in degrees and lies in the range 0 0 to 180 0 and condition and condition2 Reports true if both condition and condition are true Note that if condition is false then condition2 will not be run since it can t affect the result 1f pxcor gt 0 and pycor gt 0 set pcolor blue the upper right quadrant of 7 patches turn blue any any agentset Reports true if the given agentset is non empty false otherwise Equivalent to count agentset gt 0 but arguably more readable if any turtles with color red show at least one turtle is red Note nobody is not an agentset You only get nobody back in situations where you were expecting a single agent not a whole agentset If any gets nobody as input an error results See also_nobody Primitives Dictionary 195 NetLogo 3 1 4 User Manual Arithmetic Operators 4 lt gt lt gt All of these operators take two inputs and all act as infix operators going between the two inputs as in standard mathematical use NetLogo correctly supports order of operations for infix operators The operators work as follows is addition is multiplication is subtraction is division is exponentiation lt is less than gt is grea
296. r Manual primitives A command performs an action a reporter reports a value To create a new command or reporter create a class that implements the interface org nlogo api Command or org nlogo api Reporter which extend org nlogo api Primitive In most cases you can extend the abstract class org nlogo api DefaultReporter or org nlogo api DefaultCommand DefaultReporter requires that we implement Object report Argument args Context context throws Since ou ExtensionException r reporter takes an argument we also implement Syntax getSyntax Here s the implementation of our reporter in a file called IntegerList java import o public c LIE publ publ Notice rg nlogo api lass IntegerList extends DefaultReporter ake one number as input report a list ic Syntax getSyntax return Syntax reporterSyntax new int Syntax TYPE_NUMBER Syntax TYPE_LIST y ic Object report Argument args Context context throws ExtensionException create a NetLogo list for the result LogoList list new LogoList use typesafe helper method from org nlogo api Argument to access argument int n args 0 getIntegerValue if n lt 0 signals a NetLogo runtime error to the modeler throw new ExtensionException input must be positive populate the list for int i 0 i lt n i list add new Integer
297. r defined including all observer turtle and patch variables the drawing and the contents of the output area if one exists to an external file given by the string filename The result file can be read back into NetLogo with the impori world primitive export plot export all plots and export world save files in in plain text comma separated values csv format CSV files can be read by most popular spreadsheet and database programs as well as any text editor If the file already exists it is overwritten If you wish to export to a file in a location other than the model s location you should include the full path to the file you wish to export Use the forward slash as the folder separator Note that the functionality of these primitives is also available directly from NetLogo s File menu export world fire csv 7 exports the state of the model to the file fire csv 7 located in the NetLogo folder export plot Temperature c My Documents plot csv 7 exports the plot named 5 Temperature to the file plot csv located in the C My Documents folder export all plots c My Documents plots csv 77 exports all plots to the file plots csv located in the C My Documents folder extract hsb extract hsb color Reports a list of three values in the range 0 0 to 1 0 representing the hue saturation and brightness respectively of the given NetLogo color in the range 0 to 140 212 Primitives Dictionary
298. r example inside an ask then it will exist only inside those brackets to swap colors end set set Colors turtlel turtle2 let temp color of turtlel color of turtlel color of turtle2 color of turtle2 temp NetLogo represents colors as numbers in the range 0 to 140 with the exception of 140 itself Below is a chart showing the range of colors you can use in NetLogo gray 5 red 15 orange 25 brown 35 yellow 45 green 55 lime 65 turquoise 75 cyan 85 sky 95 blue 105 violet 115 magenta 125 pink 135 black 0 The chart shows that e Some of the colors have names You can use these names in your code e Every named color except black and white has a number ending in 5 e On either side of each named color are darker and lighter shades of the color e O is pure black 9 9 is pure white Programming Guide 108 118 137 138 white 9 9 9 9 9 19 199 29 299 E 399 49 49 9 59 599 69 69 9 79 79 9 89 89 9 99 999 109 109 9 119 119 9 129 129 9 139 139 9 89 NetLogo 3 1 4 User Manual e 10 20 and so on are all so dark they appear black 19 9 29 9 and so on are all so light they appear white Code Example The color chart was made in NetLogo with the Color Chart Example model You can also view a similar chart and experiment with the colors by opening the Color Swatches from the Tools Menu 606 Color Swatches white 9 9999 A Pr
299. r message error message Reports a string describing the error that was suppressed by carefully This reporter can only be used in the second block of a carefully command See also carefully 210 Primitives Dictionary NetLogo 3 1 4 User Manual every every number commands Runs the given commands at most every number seconds By itself every doesn t make commands run over and over again You need to use every inside a loop or inside a forever button if you want the commands run over and over again every only limits how often the commands run More technically its exact behavior is as follows When an agent reaches an every it checks a timer to see if the given amount of time has passed since the last time the same agent ran the commands in the every in the same context If so it runs the commands otherwise they are skipped and execution continues Here in the same context means during the same ask or button press or command typed in the Command Center So it doesn t make sense to write ask turtles every 0 5 because when the ask finishes the turtles will all discard their timers for the every The correct usage is shown below every 0 5 ask turtles fd 1 7 twice a second the turtles will move forward 1 every 2 set index index 1 7 every 2 seconds index is incremented See also_wait exp exp number Reports the value of e raised to the number power Note This is the same as e nu
300. rara 138 Calculator HubNeL cai dao 139 ROQUIES MENS ia A AAA ia 139 Teacher O A ANO 139 HubNet Authoring Guide a aavthnan dai adia SUR Sinden RU a A AD eid abeecasveantadiadagennastaanncae 139 Getting Nel iaa 139 H bNet Authoring Guides sisi iii ttisher A dada ia 141 General HubNet INfOrMAtiQON cccccooncccccnnncnccnnnanoninnnonccnnnnnnccnnnon nono nonananono nana ncnonnnnccncnanananos 141 Netlogo PriMitiVeS icono cacatengetadvcnctieaceangcecasedoadestdacdedacceteadsdendeceadecatvciecaecesvacenaas 141 SO A O 141 Data CXIACHON caes idas fia so AG A aa q a OD a CE da CR A a E ideados 142 SOCIA ai AS RE RREO 143 Example cia raacia idad 144 Calculator HubNet INfOrMatiQN ccooooncccccnnnccncnnnccncnnnoncnnnnnanccno nono nonononanancno nana nano nnna cana nanananas 144 yq ON 144 Computer HubNet INnforMatiQN ccccccnononccnnnnnnccnnnnnnnnnnnnncccnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnrnninnnnnnnnnos 145 How To Make an Interface for a ClieMt oo coonncccccnnnccccnnnncncnnnananonononananononanonononaninanono 145 View Updates on the Clean da 146 Plot Updates On tne CIS a 147 Clicking in the View on ClientS ccccccconoooocncccnccnononononncncnnnnccnonnnnnnnnnnnccconnnannnnnnnnnnnnnn 147 NetLogo 3 1 4 User Manual Table of Contents HubNet Authoring Guide Text Area for Input and Displavicaii dci 147 Extensions QUIde A EE E SP AE E ad da 149 USING EXTENSIONS aiii dia 149 ADM Sa A A iodo 150 Witing Exte sioNS ee e delves inten
301. rary which is Copyright c 2003 2005 Werner Randelshofer _http www randelshofer ch werner randelshofer bluewin ch All Rights Reserved The library is covered by the GNU LGPL Lesser General Public License The text of that license is included in the docs folder which accompanies the NetLogo download and is also available from http Awww gnu org copyleft lesser html For the system dynamics modeler NetLogo uses the JHotDraw library which is Copyright c 1996 1997 by IFA Informatik and Erich Gamma The library is covered by the GNU LGPL Lesser General Public License The text of that license is included in the docs folder which accompanies the NetLogo download and is also available from_http www gnu org copyleft lesser html For movie making NetLogo uses code adapted from sim util media MovieEncoder java by Sean Luke distributed under the MASON Open Source License The copyright for that code is as follows This software is Copyright 2003 by Sean Luke Portions Copyright 2003 by Gabriel Catalin Balan Liviu Panait Sean Paus and Dan Kuebrich All Rights Reserved Developed in Conjunction with the George Mason University Center for Social Complexity By using the source code binary code files or related data included in this distribution you agree to the following terms of usage for this software distribution All but a few source code files in this distribution fall under this license the exceptions contain open source
302. re how having more or fewer turtles initially affect the plots over time Second wouldn t it be nice to adjust the energy the turtles gain and lose as they eat grass and reproduce e Make a slider called energy from grass e Make another slider called birth energy 64 Tutorial 43 Procedures NetLogo 3 1 4 User Manual e Then inside of cat grass make this change to cal grass ask turtles if pcolor green set pcolor black set energy energy energy from grass ifelse show energy set label energy set label end e And inside of reproduce make this change to reproduce ask turtles if energy gt birth energy Setlencegyienengy birth energy hatch 1 set energy birth energy Finally what other slider could you add to vary how often grass grows back Are there rules you can add to the movement of the turtles or to the newly hatched turtles that happen only at certain times Try writing them What s next So now you have a simple model of an ecosystem Patches grow grass turtles wander eat the grass reproduce and die You have created an interface containing buttons sliders switches monitors and plots You ve even written a series of procedures to give the turtles something to do That s where this tutorial leaves off If you d like to look at some more documentation about NetLogo the Interface Guide section of the manual walks you through every element of the N
303. remove lt breed gt from agent remove lt breed gt to agent _ Yemove lt breed gt with agent __remove lt breeds gt from agentset __remove lt breeds gt to agentset __remove lt breeds gt with agentset Used for removing link turtles between node turtles __remove lt breed gt to removes the link turtle from the caller to agent remove lt breed gt to removes all agents in agentset remove lt breed gt from removes the link turtle from agent or all agents in agentset to the caller remove lt breed gt with ignores direction and removes link turtles going in either direction __remove lt breed gt to and remove lt breed gt from throw an error if the caller is not linked to agent or one or more agents in agentset in the direction that they try to remove in __remove lt breed gt with throws an error only if there are no links of links breed in either direction breed links link breed for network links to reduce friends node procedure remove link to one of __link neighbors end to become nasty node procedure remove links to __link neighbors breaks any friendships this node had end This command is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details repeat repeat number commands Runs commands number times pd repeat 36 fd 1 rt 10 the turtle draws a circle replace item replace item index list value
304. rmation about HubNet see the HubNet Guide What s Next If you want to learn how to explore models at a deeper level Tutorial 2 Commands will introduce you to the NetLogo modeling language In_Tutorial 3 Procedures you can learn how to alter and extend existing models and build your own models 36 Tutorial 1 Models Tutorial 2 Commands In Tutorial 1 you had the opportunity to view some of the NetLogo models and you have successfully navigated your way through opening and running models pressing buttons changing slider and switch values and gathering information from a model using plots and monitors In this section the focus will start to shift from observing models to manipulating models You will start to see the inner workings of the models and be able to change how they look Sample Model Traffic Basic e Go to the Models Library File menu e Open up Traffic Basic found in the Social Science section e Run the model for a couple minutes to get a feel for it e Consult the Information tab for any questions you may have about this model In this model you will notice one red car in a stream of blue cars The stream of cars are all moving in the same direction Every so often they pile up and stop moving This is modeling how traffic jams can form without any cause such as an accident a broken bridge or an overturned truck No centralized cause is needed for a traffic jam to form You may alter the s
305. rnate method of downloading the software Downloading NetLogo takes too long Is it available any other way such as on a CD At present no If this is a problem for you contact us at feedback ccl northwestern edu I downloaded and installed NetLogo but the Models Library has few or no models in it How can fix this So far users reporting this problem all used the without VM download option for Windows Uninstall NetLogo and try the with VM download instead Even if the with VM download fixes it for you please contact us at bugs Dccl northwestern edu so we can find out more details about your setup We d like to fix this in a future version but to troubleshoot it we need help from users Can have multiple versions of NetLogo installed at the same time Yes When you install NetLogo the folder that is created contains has the version number in its name so multiple versions can coexist On Windows systems whichever version you installed last will be the version that opens when you double click a model file in Windows Explorer On Macs you can control what version opens via Get Info in the Finder I m on a UNIX system and can t untar the download Why Some of the files in the tarball have very long pathnames too long for the standard tar format You must use the GNU version of tar instead or another program which understands the GNU tar extensions On some systems the GNU version of tar is available under the n
306. roup Instead of asking 150 of your closest friends to gather and randomly group let s have the computer simulate this situation for us What to do 1 Press the go button Pressing go again will stop the model manually 2 Observe the movement of people until the model stops 3 Watch the plots to see what s happening in another way Now how many people are in each group Originally you may have thought 150 people splitting into 10 groups would result in about 15 people in each group From the model we see that people did not divide up evenly into the 10 groups instead some groups became very small whereas other groups became very large Also the party changed over time from all mixed groups of men and women to all single sex groups What could explain this 24 Sample Model Party NetLogo 3 1 4 User Manual There are lots of possible answers to this question about what happens at real parties The designer of this simulation thought that groups at parties don t just form randomly The groups are determined by how the individuals at the party behave The designer chose to focus on a particular variable called tolerance erro Tolerance is defined here as the percentage of people of the opposite sex an individual is comfortable with If the individual is in a group that has a higher percentage of people of the opposite sex than their tolerance allows then they become uncomfortable and leave the group to
307. rsion Java version and so on This information is available from NetLogo s About NetLogo menu item In saved applets the same information is available by control clicking Mac or right clicking the white background of the applet e Any error messages that were displayed Contacting Us 21 22 NetLogo 3 1 4 User Manual Contacting Us Sample Model Party This activity is designed to get you thinking about computer modeling and how you can use it It also gives you some insight into the NetLogo software We encourage beginning users to start with this activity At a Party Have you ever been at a party and noticed how people cluster in groups You may have also noticed that people do not stay within one group but move throughout the party As individuals move around the party the groups change If you watched these changes over time you would notice patterns forming For example in social settings people tend to exhibit different behavior than when they are at work or home Individuals who are confident within their work environment may become shy and timid at a social gathering And others who are quiet and reserved at work may be the party starter with friends The patterns may also depend on what kind of gathering it is In some settings people are trained to organize themselves into mixed groups for example party games or school like activities But in a non structured atmosphere people tend to group in a more rand
308. runs slowly How can speed it up Here s some ways to make it run faster without changing the code e Edit the forever buttons in your model and turn off the Force view update after each run checkbox This allows the view to skip frames which may speed up models which are graphics intensive See the Buttons section of the Programming Guide for a discussion of this e Use the freeze switch in the view control strip or the no display command to freeze the view temporarily For example to go FAQ Frequently Asked Questions 179 NetLogo 3 1 4 User Manual no display display end If you use this technique you should turn off the Force view update checkbox since the display command already forces a view update e If your model is using all available RAM on your computer then installing more RAM should help If your hard drive makes a lot of noise while your model is running you probably need more RAM e Use turtle size 1 1 5 or 2 as these sizes are cached by NetLogo In many cases though if you want your model to run faster you may need to make some changes to the code Usually the most obvious opportunity for speedup is that you re doing too many computations that involve all the turtles or all the patches Often this can be reduced by reworking the model so that it does less computation per time step If you need help with this if you contact us at feedback ccl northwestern edu we may be able to help if you can send us
309. s hubnet broadcast view This broadcasts the current state of the 2D View in the NetLogo model to all the Computer HubNet Clients It does nothing for Calculator HubNet hubnet send list of strings tag name value hubnet send string tag name value When using Calculator HubNet this primitive acts in exactly the same manner as hubnet broadcast For Computer HubNet it has the following effects 0 When string is the first input this sends value from NetLogo to the tag tag name on the client that has string for a user name O When list of strings is the first input this sends value from NetLogo to the tag tag name on all the clients that have a user name that is in the list of strings 0 All the information for the current state of the View is sent at this time regardless of whether the clients Views were already up to date Note Sending a message to a non existent client using hubnet send generates a hubnet exit message hubnet send view string hubnet send view list of strings For Calculator HubNet does nothing For Computer HubNet it acts as follows 0 For a string this sends the current state of the 2D View in the NetLogo model to the Computer HubNet Client with string for its user name 0 For a list of strings this sends the current state of the 2D View in the NetLogo model to all the Computer HubNet clients that have a user name that is in the list of strings 0 All the information for the current state of the view is sent at thi
310. s An agentset is exactly what its name implies a set of agents An agentset can contain either turtles or patches but not both at once An agentset is not in any particular order In fact its always in a random order And every time you use it the agentset is in a different random order This helps you keep your model from treating any particular turtles or patches differently from any others unless you want them to be Since the order is random every time no one agent always gets to go first You ve seen the turtles primitive which reports the agentset of all turtles and the patches primitive which reports the agentset of all patches But what s powerful about the agentset concept is that you can construct agentsets that contain only some turtles or some patches For example all the red turtles or the patches with pxcor evenly divisible by five or the turtles in the first quadrant that are on a green patch These agentsets can 92 Programming Guide NetLogo 3 1 4 User Manual then be used by ask or by various reporters that take agentsets as inputs One way is to use turtles here Or turtles at to make an agentset containing only the turtles on my patch or only the turtles on some other particular patch There s also turtles on so you can get the set of turtles standing on a given patch or set of patches or the set of turtles standing on the same patch as a given turtle or set of turtles Here are some more examples of how to m
311. s It reports TRUE if there is new data and FALSE if there is not hubnet fetch message If there is any new data sent by the clients this retrieves the next piece of data so that it can be accessed by hubnet message This will cause an error if there is no new data from the clients So be sure to check for data with hubnet message wait ing before calling this hubnet message source This reports the user name of the client that sent the data This will cause an error if no data has been fetched So be sure to fetch the data with hubnet fetch message before calling this hubnet message tag This reports the tag that is associated with the data that was sent For Calculator HubNet this will report one of the variable names set with the hubnet set client interfac primitive For Computer HubNet this will report one of the Display Names of the interface elements in the client interface See_below for more information about the Computer HubNet tags For both types of HubNet this primitive will cause an error if no data has been fetched So be sure to fetch the data with hubnet fetch message before calling this hubnet message This reports the data collected by hubnet fetch message This will cause an error if no data has been fetched So be sure to fetch the data with hubnet fetch message before calling this There are two additional data extraction primitives that are only used in Computer HubNet models hubnet enter messa
312. s ViSIOMN cccccccccccsssssesneeeeeeeesseseneeeeeeeceseesseeneeeeeeeeeeessssenaaees 185 Can agents sense what s in the drawing layer serenas 186 Does NetLogo have a command like StarLogo s grab command 186 tried to put at after the name of a variable for example variable at 1 0 but NetLogo won t let me Why not e eeerararereeaaeaaaaeaaarereaaanana 186 l m getting numbers like 0 10000000004 and 0 799999999999 instead of 0 1 and 08 WAY NNE ROS REED ND ROD SEDA RIO Sa Aa aa ad 186 The documentation says that random float 1 0 might return 0 0 but will never return 1 0 What if want 1 0 to be included errar 186 How can keep two turtles from occupying the same patch 187 How can find out if a turtle is dead errantes cara 187 How do find out how much time has passed in my model na 187 Does NetLogo have Arrays cccccecsssssceceeeeesssennnaeeeeeeessseseeceeeeeeeeesesseeneseeeeeeeeessseenaaees 187 vii NetLogo 3 1 4 User Manual Table of Contents FAQ Frequently Asked Questions Does NetLogo have associative arrays or lookup tables nenene 188 How can use different patch neighborhoods circular Von Neumann Moore EOR EAA A a A A REE EEE EE de A A 188 Can connect turtles with lines to indicate connections between them 188 How can convert an agentset to a list of agents or vice versa
313. s does not apply a braking force as output port off does Therefore the motor will gradually slow down before stopping completely This will have the same effect as output port off on most output devices other than motors The output ports effected by this command are determined by the talk to output ports command The following code will will turn on output port a for 1 second and then stop the motor gradually talk to output ports a output port on wait 1 output port coast output port off output port off Turns off power to the output ports If using motors a braking force is applied The output ports effected by this command are determined by the talk to output ports command output port reverse output port reverse Reverses the direction of the output ports The output ports effected by this command are determined by the talk to output ports command output port that this way output port thatway output port thisway Apply power to the output port in a given direction Output ports can be powered in two directions arbitrarily called thisway and thatway The output ports effected by the command are determined by the talk to output ports command Note that this is different ffom output port reverse because thisway and thatway will always be the same direction provided the connector s polarity is the same talk to output poris talk to output ports output portlist This command will set the corresponding output ports as a
314. s and issue commands to the turtle You can also open a turtle monitor via the View see the View section below Patch Monitor Displays the values of all of the variables in a particular patch ou can can also edit the values of the patch s variables and issue commands to the patch You can also open a patch monitor via the View see the View section below Hide Show Command Makes the command center visible or invisible Note that the ommand center can also be shown or hidden or resized with 3D View Opens the 3D view See the View section for more information Color Swatches q 0 Interface Guide NetLogo 3 1 4 User Manual Opens the Color Swatches See the Color Section of the Programming Guide for details A Pe turtle shapes See the_Shapes Editor Guide for more information BehaviorSpace Guide for more information System Dynamics Opens the System Dynamics Modeler See the_System Modeler Dynamics Modeler Guide for more details HubNet Control Center Disabled if no HubNet activity is open See the HubNet Guide or more information Larger Increase the overall screen size of the model Useful on large monitors or when using a projector in front of a group Normal Size Smaller Decrease the overall screen size of the model his menu offers keyboard shortcuts for each of the tabs On Macs it s Command 1 through Command 3 On Windows it s Control 1 through Control 3 About NetLogo Information on the curre
315. s directed and the other is undirected A runtime error occurs if you try to do it If all link turtles of a breed die then you can create links of that breed that are different in flavor from the previous links In general primitives that work with directed links have in Undirected ones either omit these or use with out to and from in their names There cannot be more than one undirected link of the same breed between a pair of agents nor more than one directed link of the same breed in the same direction between a pair of agents You can have two directed links of the same breed between a pair if they are in opposite directions Layouts As part of the experimental network support we have also added several different primitives that will help you to visualize the networks The simplest is __layout circle which evenly spaces the agents around the center of the world given a radius layout radial is a good layout if you have something like a tree structure though even if there are some cycles in the tree it will still work though as there are more and more cycles it will probably not look as good layout radial takes a root agent to be the central node places it at 0 0 and arranges the nodes connected to it in a concentric pattern Nodes one degree away from the root will be arranged in a circular pattern around the central node and the next level around those nodes and so on layout radial will attempt to account for asy
316. s in the Wolf Sheep Predation model Do you ever get different results if you run the model several times with the same settings 28 Tutorial 1 Models NetLogo 3 1 4 User Manual Adjusting Settings Sliders and Switches The settings within a model give you an opportunity to work out different scenarios or hypotheses Altering the settings and then running the model to see how it reacts to those changes can give you a deeper understanding of the phenomena being modeled Switches and sliders give you access to a model s settings Here are the switches and sliders in Wolf Sheep Predation setup go a Grass settings i Sheep settings Wolf settings Let s experiment with their effect on the behavior of the model e Open Wolf Sheep Predation if it s not open already e Press setup and go and let the model run for about a 100 time ticks Note there is a readout of the number of ticks right above the plot e Stop the model by pressing the go button What happened to the sheep over time Let s take a look and see what would happen to the sheep if we change one of the settings e Turn the grass switch on e Press setup and go and let the model run for a similar amount of time as before What did this switch do to the model Was the outcome the same as your previous run Just like buttons switches have information attached to them Their information is set up in an on off
317. s time regardless of whether the clients views were already up to date Note Sending the View to a non existent client using hubnet send view generates a hubnet exit message HubNet Authoring Guide 143 NetLogo 3 1 4 User Manual When using Calculator HubNet the hubnet send and the hubnet broadcast primitives take a number a string a list of numbers or a matrix a list of lists of numbers as the value input When using Computer HubNet you may send any kind of information with the exceptions of patches turtles and agentsets Here are some examples of using the two primitives to send various types of data that you can send data type hubnet broadcast example hubnet send example t send Jimmy A 3 14 STR1 LS I TH a 3 14 SAA STRI t broadcast send 12 ERE t broadcast HERE t send t broadcast L2 t broadcast A 1 t message source Ar t send 4 susie Examples t broadcast user names jimmy bob george Hd ubnet send bob user names george susie teacher 3immy susie Study the models in the HubNet Computer Activities and the HubNet Calculator Activities sections of the Models Library to see how these primitives are used in practice in the Procedures window Disease is a good one with which to start Calculator HubNet Informatio
318. s two inputs show 62 mod 5 Primitives Dictionary 243 NetLogo 3 1 4 User Manual Z show 8 mod 3 gt L See also_remainder mod and remainder behave the same for positive numbers but differently for negative numbers modes modes list Reports a list of the most common item or items in ist The input list may contain any NetLogo values If the input is an empty list reports an empty list show modes 1 2 2 3 4 gt 2 show modes 1 2 2 3 3 4 gt 2 3 show modes 1 2 3 1 2 3 2 3 4 gt 1 2 3 show modes values from turtles pxcor 7 shows which columns of patches have the most turtles on them mouse down mouse down Reports true if the mouse button is down false otherwise Note If the mouse pointer is outside of the current view mouse down will always report false mouse inside mouse inside Reports true if the mouse pointer is inside the current view false otherwise mouse xcor mouse ycor mouse xcor mouse ycor Reports the x or y coordinate of the mouse in the 2D view The value is in terms of turile coordinates so it is a floating point number If you want patch coordinates use round mouse xcor and round mouse ycor 244 Primitives Dictionary NetLogo 3 1 4 User Manual Note If the mouse is outside of the 2D view reports the value from the last time it was inside to make the mouse draw in red if mouse down set pcolor of patch at mous
319. s2 Runs commands1 If a runtime error occurs inside commands1 NetLogo won t stop and alert the user that an error occurred It will suppress the error and run commands2 instead The error message reporter can be used in commands2 to find out what error was suppressed in commands1 See error message Note both sets of commands run without interruption as with the without interruption command carefully show 1 1 print error message gt 1 carefully show 1 0 print error message gt division by zero ceiling ceiling number Reports the smallest integer greater than or equal to number show ceiling 4 5 gt 5 show ceiling 4 5 gt 4 clear all ca clear all Resets all global variables to zero and calls clear turtles clear patches clear drawing clear all plots and clear output clear all plots clear all plots ig Clears every plot in the model See clear plot for more information clear drawing cd Primitives Dictionary 201 NetLogo 3 1 4 User Manual clear drawing Clears all lines and stamps drawn by turtles clear output clear output pa Clears all text from the model s output area if it has one Otherwise does nothing clear patches cp clear patches is Clears the patches by resetting all patch variables to their default initial values including setting their color to black clear plot clear plot In the current plot only resets all plot pens del
320. se all operations on agentsets happen in random order Once scheduled an agent s turn ends only once it performs an action that affects the state of the world such as moving or creating a turtle or changing the value of a global turtle or patch 188 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual variable Setting a local variable doesn t count To prolong an agent s turn use the without interruption command The command blocks inside some commands such as cct and hat ch have an implied without interruption around them NetLogo s scheduling mechanism is completely deterministic Given the same code and the same initial conditions the same thing will always happen if you are using the same version of NetLogo and begin your model run with the same random seed In general we suggest you write your NetLogo code so that it does not depend on a particular scheduling mechanism We make no guarantees that the scheduling algorithm will remain the same in future versions How do stop foreach To stop a foreach from executing you need to define a separate procedure that contains only the foreach for example to test foreach 12 3 if 2 stop print end This code will only print the number 1 The stop returns from the current procedure so nothing after the foreach will be executed either If the procedure is a reporter procedure use report instead of stop How do make an e
321. se extensions that require additional extra jars Also unsigned applets aren t allowed to access external devices anyway 160 GoGo Extension NetLogo 3 1 4 User Manual For examples that use the GoGo extension see the GoGo section under Code Examples in NetLogo s Models Library Primitives gogo open gogo open gogo open gogo ports output port coast output port off output port reverse output port thailthis way ping sensor set output port power talk to output ports gogo close gogo close Close the connection to the GoGo Board See also gogo open and gogo open gogo open gogo open port name Open a connection to the GoGo Board connected to serial port named port name See gogo ports for more information about port names If the GoGo Board is not responding or you attempt to open a port without a GoGo Board connected to it an error will be generated Example gogo open COM1 See also gogo open and gogo close gogo open gogo open Reports true if there is a connection to a GoGo board open Reports false otherwise gogo poris gogo ports Reports a list of serial port names which a GoGo Board may be connected to On certain computers you might get a list of two or three different serial ports In that case try to open each of them until the connection is successful GoGo Extension 161 NetLogo 3 1 4 User Manual output port coast output port coast Turns off the power of the active ports When attached to motor
322. send text back to the server If you are interested in using it in an activity please_contact us for further information HubNet Authoring Guide 147 NetLogo 3 1 4 User Manual 148 HubNet Authoring Guide Extensions Guide NetLogo allows users to write new commands and reporters in Java and use them in their models This section of the User Manual introduces this facility The first part discusses how to use an extension in your model once you have written one or once someone has given you one The second part is intended for Java programmers interested in writing their own extensions Caution The extensions facility is new in NetLogo 2 0 1 and is still in an early stage of development Therefore it is considered experimental It is likely to continue to change and grow If you write an extension now it may need changes in order to continue to work in future NetLogo versions e Using Extensions e Writing Extensions The NetLogo API Specification contains further details Using Extensions NetLogo extensions have names that end in jar short for Java Archive To use an extension in a model add the __ extensions keyword at the beginning of the Procedures tab before declaring any breeds or variables The keyword begins with two underscores to indicate that it is experimental In a future NetLogo version it may have a different name and syntax __ extensions takes one input a list of strings Each string contains the n
323. set energy energy 10 ifelse show energy set label energy set label end The eat grass procedure introduces the ifelse command Look at the code carefully Each turtle when it runs these new commands checks the value of show energy determined by the switch If the switch is on comparison is true and the turtle will run the commands inside the first set of brackets In this case it assigns the value for the energy to the label of the turtle If the comparison is false the switch is off then the turtle runs the commands inside the second set of brackets In this case it removes the text labels by setting the label of the turtle to be nothing In NetLogo a piece of text is called a string A string is a sequence of letters and other characters written between double quotes Here we have two double quotes right next to each other with nothing in between them That s an empty string If a turtle s label is an empty string no text is attached to the turtle e Test this in the Interface tab by running the model using the setup and go buttons switching the show energy switch back and forth When the switch is on you ll see the energy of each turtle go up each time it eats grass You ll also see its energy going down whenever it moves 58 Tutorial 3 Procedures NetLogo 3 1 4 User Manual 2000 ot Ig 0 55 500 5500 soc 4000 sde 2500 4 4500 esac 4500 6000 150 0 3000 an 150 o 700 E
324. sort by size of 1 lt size of 2 turtles This returns a list of turtles sorted in ascending order by their turtle variable size Asking a list of agents Once you have a list of agents you might want to ask them each to do something To do this use the foreach and ask commands in combination like this foreach sort turtles ask Programming Guide 101 NetLogo 3 1 4 User Manual This will ask each turtle in ascending order by who number Substitute patches for turtles to ask patches in left to right top to bottom order If you use foreach like this the agents in the list run the commands inside the ask sequentially not concurrently Each agent finishes the commands before the next agent begins them Note that you can t use ask directly on a list of turtles ask only works with agentsets and single agents Math NetLogo supports two different kinds of math integer and floating point Integers have no fractional part and may range from 2147483648 to 2147483647 2 31 to 2 31 1 Integer operations that exceed this range will not cause runtime errors but will produce incorrect answers Floating point numbers are numbers containing a decimal point In NetLogo they operate according to the IEEE 754 standard for double precision floating point numbers These are 64 bit numbers consisting of one sign bit an 11 bit exponent and a 52 bit mantissa See the IEEE 754 standard for details Any operation which produces
325. ss in the HubNet Control Center is not always the entire IP address of the server e Authoring new HubNet activities is more arcane and difficult than it should be e Computer HubNet has only been tested on LANs and not on dial up connections or WANs Calculator HubNet Requirements To use Calculator HubNet you need e A computer with an attached projector This computer will run NetLogo and project the simulation for class viewing e A classroom set of Texas Instruments Tl 83 graphing calculators e The Ti Navigator calculator network from Texas Instruments NOTE Calculator HubNet works with a prototype version of the Tl Navigator system and is not yet compatible with the commercially available version To learn more about the TI Navigator system please visit the Texas Instruments web site We are actively working in partnership with Texas Instruments on integrating the new Tl Navigator with Calculator HubNet We expect to release a new version in the near future For more information about Calculator HubNet please refer to the Participatory Simulations Guide which can be found on the Participatory Simulations Project web site Teacher workshops For information on upcoming workshops and NetLogo and HubNet use in the classroom please contact us at feedbackOccl northwestern edu HubNet Authoring Guide To learn about authoring or modifying HubNet activities see the HubNet Authoring Guide Getting help If you have a
326. ss you installed NetLogo in a different location Edit this line lax nl java option additional Djava ext dirs server Dsun java2d noddraw true and add Dsun java2d ddoffscreen false at the end of the last line You can see the details of the Java bug and vote for Sun to fix it_here How do change how many patches there are A quick method is to use the three sets of black arrows in the upper left corner of the 2D view Another method is as follows Select the 2D view by dragging a rectangle around it with the mouse Click the Edit button in the Toolbar A dialog will appear in which you may enter new values for Screen Edge X and Screen Edge Y You can also right click Windows or control click Mac on the 2D view to edit it or select it then double click Can I use the mouse to paint in the view NetLogo does not have a built in set of painting tools for painting in the view But with only a few lines of code you can add painting capability to your model To see how it s done look at Mouse Example in the Code Examples section of the Models Library The same techniques can be used to let the user interact with your model using the mouse in other ways too Another possibility is to use a special drawing model such as the Drawing Tool model by James Steiner which is available from_http ccl northwestern edu netlogo models community A third possibility is to create an image in another program and import it See the an
327. st input specifies which item in the list is to be changed 0 means the first item 1 means the second item and so forth To add an item say 42 to the end of a list use the 1put reporter fput adds an item to the beginning of a list set mylist lput 42 mylist mylist is now 2 7 10 Bob 3 0 2 42 But what if you changed your mind The but 1ast b1 for short reporter reports all the list items but the last set mylist but last mylist mylist is now 2 7 10 Bob 3 0 2 Suppose you want to get rid of item 0 the 2 at the beginning of the list set mylist but first mylist mylist is now 7 10 Bob 3 0 2 Suppose you wanted to change the third item that s nested inside item 3 from 2 to 9 The key is to realize that the name that can be used to call the nested list 3 0 2 is item 3 mylist Then the replace item reporter can be nested to change the list within a list The parentheses are added for clarity Programming Guide 99 NetLogo 3 1 4 User Manual set mylist replace item 3 mylist replace item 2 item 3 mylist 9 mylist is now 7 10 Bob 3 0 9 Iterating over lists If you want to do some operation on each item in a list in turn the foreach command and the map reporter may be helpful foreach is used to run a command or commands on each item in a list It takes an input list and a block of commands like this foreach 2 4 6 E creo show created turtles gt created 2 turtles
328. started a HubNet activity but when participants open a HubNet Client my activity isn t listed On some networks the HubNet Client cannot automatically detect a HubNet server Tell your participants to manually enter the server name and port of your HubNet server which appear in the HubNet Control Center Note The technical details on this are as follows In order for the client to detect the server multicast routing must be available between them Not all networks support multicast routing In HubNet Guide 137 NetLogo 3 1 4 User Manual particular networks that use the IPsec protocol typically do not support multicast The IPsec protocol is used on many virtual private networks VPNs When a participant tries to connect to an activity nothing happens the client appears to hang or gives an error saying that no server was found If your computer or network has a firewall it may be impeding the HubNet server from communicating Make sure that your computer and network are not blocking ports used by the HubNet server ports 9173 9180 The view on the HubNet client is grey e Verify that the Mirror 2D view checkbox in the HubNet Control Center is selected e Make sure that the display switch in the model is on e The view on the server must be exactly the same size as on the client If you changed the size of the view on the HubNet server you need to restore it to its original dimensions There is no view on the HubNet client
329. stom By default the world has a center configuration where 0 0 is at the center of the world and the user defines the number of patches from the center to the right and left boundaries and the number of patches from the center to the top and bottom boundaries For Example If you set Max Pxcor 10 Min Pxcor will automatically be set to 10 thus there are 10 patches to the left of the origin and 10 patches to the right of patch 0 0 74 Interface Guide NetLogo 3 1 4 User Manual A Corner configuration allows the user to define the location of the origin as one of the corners of the world upper left upper right lower left or lower right Then you define the far boundary in the x and y directions For example if you choose to put the origin in the lower left corner of the world you define the right and top positive boundaries Edge mode allows you to place the origin along one of the edges x or y then define the far boundary in that direction and both boundaries in the other For example if you select edge mode along the bottom of the world you must also define the top boundary as well as the left and the right Finally Custom mode allows the user to place the origin at any location in the world though patch O 0 must still exist in the world As you change the settings you will notice that the changes you make are reflected in the preview on the right side of the panel which shows the origin and the boundaries The width and heigh
330. swer to_Can import a graphic into NetLogo How big can my model be How many turtles patches procedures buttons and so on can my model contain We have tested NetLogo with models that use hundreds of megabytes of RAM and they work fine We haven t tested models that use gigabytes of RAM though Theoretically it should work but you might hit some limits that are inherent in the underlying Java VM and or operating system either designed in limits or bugs The NetLogo engine has no fixed limits on size On Macintosh and Windows operating systems though by default NetLogo ships with a 512 megabyte ceiling on how much total RAM it can use On other operating systems the ceiling is determined by your Java VM Here s how to raise the limit if you need to e Windows Edit this section of the NetLogo lax file in the NetLogo folder 178 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual LAX NL JAVA OPTION JAVA HEAP SIZE MAX allow the heap to get huge lax nl java option java heap size max 536870912 Note this might not help on some Windows 98 or Windows ME systems e Macintosh Edit the Contents Info plist file in the NetLogo application package You can reach this file by control clicking the application in the Finder and choosing Show Package Contents from the popup menu The relevant section is this the second number is the ceiling lt key gt VMOpt ions lt key gt lt string gt Xms16
331. t and how NetLogo helps learners explore it you may wish to explore NetLogo s Models Library It contains models that demonstrate these ideas in systems of all kinds For a longer discussion of emergence and how NetLogo helps learners explore it see Modeling Nature s Emergent Patterns with Multi agent Languages Wilensky 2001 What s Next The section of the User Manual called_Tutorial 1 Running Models goes into more detail about how to use the other models in the Models Library If you want to learn how to explore the models at a deeper level Tutorial 2 Commands will introduce you to the NetLogo modeling language Eventually you ll be ready for Tutorial 3 Procedures where you can learn how to alter and extend existing models to give them new behaviors and build your own models 26 Sample Model Party Tutorial 1 Models If you read the Sample Model Party section you got a brief introduction to what it s like to interact with a NetLogo model This section will go into more depth about the features that are available while you re exploring the models in the Models Library Throughout all of the tutorials we ll be asking you to make predictions about what the effects of making changes to the models will be Keep in mind that the effects are often surprising We think these surprises are exciting and provide excellent opportunities for learning Some people have found it helpful to print out the tutorials in order to work
332. t formats are specified is to send table output to the system standard output stream Here is one final example that shows how to run an experiment setup which is stored in a separate XML file instead of in the model file java server Xmsl16M Xmx512M cp NetLogo jar org nlogo headless HeadlessWorkspace model Fire nlogo N setup file fire setups xml xperiment experiment 3 If the XML file contains more than one experiment setup it is necessary to use the experiment argument to specify the name of the setup to use The next section has information on how to create standalone experiment setup files using XML Setting up experiments in XML We don t yet have detailed documentation on authoring experiment setups in XML but if you already have some familiarity with XML then the following pointers may be enough to get you started The structure of BehaviorSpace experiment setups in XML is determined by a Document Type Definition DTD file The DTD is stored in NetLogo jar as system behaviorspace dtd JAR files are also zip files so you can extract the DTD from the JAR using Java s jar utility or with any BehaviorSpace Guide 133 NetLogo 3 1 4 User Manual program that understands zip format The easiest way to learn what setups look like in XML though is to author a few of them in BehaviorSpace s GUI save the model and then examine the resulting nlogo file in a text editor The experiment setups are st
333. t is procedures that report return a value must be defined with to report instead of to The command to report a value from a reporter procedure is report not output e When defining a procedure the inputs to the procedure must be enclosed in square brackets e g to square x e Variable names are always used without any punctuation always foo never foo or foo To make this work instead of a make command taking a quoted argument we supply a set special form which does not evaluate its first input As a result procedures and variables occupy a single shared namespace The last three differences are illustrated in the following procedure definitions most Logos NetLogo to square x to report square x output x x report x x end end Deeper differences e NetLogo is lexically scoped not dynamically scoped e NetLogo has no word data type what Lisp calls symbols Eventually we may add one but since it is seldom requested it may be that the need doesn t arise much in agent based modeling We do have strings In most situations where traditional Logo would use words we simply use strings instead For example in Logo you could write see spot run alist of words but in NetLogo you must write see spot run astring or see spot run a list of strings instead e NetLogo s run command works on strings not lists since we have no word data type and does not permit the definition or redefinition of
334. t of the world are displayed below the preview Also below the preview there are two checkboxes the world wrap settings These allow you to control the topology of the world Notice when you click the check boxes the preview indicates which directions allow wrapping and the name of the topology is displayed next to the world dimensions See the Topology Section of the Programming Guide for more information The view settings allow you to customize the look of the view without changing the world Changing view settings will never force a world reset To change the size of the 2D View adjust the Patch Size setting measured in pixels This does not change the number of patches only how large the patches appear in the 2D View Note that the patch size does not affect the 3D View as you can simply make the 3D View larger by making the window larger The Turtle Shapes checkbox performs the same function as the shapes button in the control strip discussed above The Smooth edges checkbox controls the use of anti aliasing in the 3D view only It will make the lines appear less jagged but it will slow down the model Turtle and patch monitors are easily available through the View just control click Macintosh or right click other systems on the turtle or patch you want to inspect and choose inspect turtle or inspect patch from the popup menu You can also watch follow or ride a turtle by selecting the appropriate item in the
335. t radial__ layout spring layout tutte lt breed gt neighbor lt breed gt neighbors lt breed gt with__my lt breeds gt my in lt breeds gt my out lt breeds gt other end_ out lt breed gt neighbor out lt breed gt neighbors out lt breed gt to remove lt breed gt from remove lt breeds gt from_ remove lt breed gt to remove lt breeds gt to _ remove lt breed gt with _ remove lt breeds gt with Movie primitives movie cancel movie close movie grab view movie grab interface movie set frame rate movie start movie status System primitives neilogo version Built In Variables Turtles breed color heading hidden label label color pen mode pen size shape size who xcor ycor Primitives Dictionary 193 NetLogo 3 1 4 User Manual Patches pcolor plabel plabel color pxcor pycor Other 2 Keywords breed end globals patches own to to report turtles own Constants Mathematical Constants e 2 718281828459045 pi 3 141592653589793 Boolean Constants false true Color Constants black 0 0 gray 5 0 white 9 9 red 15 0 orange 25 0 brown 35 0 yellow 45 0 green 55 0 lime 65 0 turquoise 75 0 cyan 85 0 sky 95 0 blue 105 0 violet 115 0 magenta 125 0 pink 135 0 See the_Colors section of the Programming Guide for more details 194 Primitives Dictionary NetLogo 3 1 4 User Manual A abs abs number Reports the absolute value of numbe
336. t really must be possible to get 1 0 you can use precision to round your answer to a certain number of decimal places For example print precision random float 1 0 10 186 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual 0 2745173723 If you use this method note that 0 0 and 1 0 are only half as likely to come up as other answers To see why this is so consider the case where you only keep one digit after the decimal places Results between 0 0 and 0 5 get rounded to 0 0 but results between 0 5 and 1 5 get rounded to 1 0 the latter range is twice as large So if you want 0 0 0 1 0 2 0 9 and 1 0 to all be equally likely you must write random 11 10 How can I keep two turtles from occupying the same patch See One Turtle Per Patch Example in the Code Examples section of the Models Library How can find out if a turtle is dead When a turtle dies it turns into nobody nobody is a special value used in NetLogo used to indicate the absence of a turtle or patch So for example if turtle 0 nobody You could also use is turtle if is turtle turtle O How do find out how much time has passed in my model NetLogo does not automatically keep track of this If you want to keep track of the passage of time add a global variable to your model with a name like clock or steps In your setup procedure set the variable to 0 In your go procedure increment the variable Many of the mo
337. taia 126 BehaviorSpace QUIE ai anclada 127 What is BehaviorSpace nidad ic 127 WhyBahavoOrSpaceo sisi 127 ElIStOFCal Note e e oat ln eR ee ca ida 128 FRONIN OIRO sas secs am sie ds a aa does dia 128 Managing experiment SelupS occoccconcconcconcnnnnnonnnnnononnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnninnninnnnss 128 Creating an experiment SOD viii oca rr ii 128 Running an EXPeriIMeNb ococccccccnncnnncnnncnnncnonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnrnnnninenineness 131 Advanced MUET le e MEA descem iam assa nadas idad datada 131 Running from the command ING aiii iaa 131 Setting up experiments in XAML 102 iii 133 Controllina ABL EEEE E E a 134 AA E EAE EEEE A E D EE EE S E A EESTE 134 HubNet GUid8 cooocccccoconococonononocononanacononanarononanarononann coronan rr conan rr conan nenna nnna nananana 135 Understanding HubNet ooccccccnnccnncnnncnnncnnnccnnnennnennnnnnennnennnennnernnrrnn erre rene 135 NOOO E A I E ia 135 HubNer r ArcMNeCt E ina A a A AiR 135 Computer dubNel ciar ia 136 A O do pe a ede lS oe tas a dt Ta 136 REQUIFEMENHS cccccecccsceeneceeeeaeeeaeceaeeeaeceecaeeceaeceaeceaecececeaecsaeceeceeeceseseeeeeaeeceneeeeesaees 136 SLU ANACO SR 136 HubNet Control Centel occcccncncccccncncccnononocincnononcnonononcncnononanono nono ncnononancno no na nnn cnn naninannns 137 Troubleshooting si cedssarbenseedatesitess steed RETOS NAO OTRA ET A AGAR IAE 137 KNOWN LiMILatiONS A EEE E AT EE arara era arena a
338. te you only have to give the command itself e Press setup What happened Why did the View revert back to the old version with the black background and white road Upon pressing the setup button the model will reconfigure itself back to the settings outlined in the Procedures tab The Command Center is not often used to permanently change the model It is most often used as a tool to customize current models and allows for you to manipulate the NetLogo world to further answer those What if questions that pop up as you are investigating the models The Procedures tab is explained in the next tutorial and in the_Programming Guide Now that we have familiarized ourselves with the Command Center let s look at some more details about how colors work in NetLogo Working With Colors You may have noticed in the previous section that we used two different words for changing color color and pcolor What is the difference between color and pcolor e Choose turtles from the popup menu in the Command Center or use the tab key e Type set color blue and press return What happened to the cars 40 Tutorial 2 Commands NetLogo 3 1 4 User Manual Think about what you did to make the cars turn blue and try to make the patches turn red If you try to ask the patches to set color red an error message occurs Command Center 2 turtles gt set color yellow ERROR You can t use COLOR in a patch context because COLOR
339. ter than is equal to is not equal to lt is less than or equal gt is greater than or equal Note that the subtraction operator always takes two inputs unless you put parentheses around it in which case it can take one input For example to take the negative of x write x with the parentheses All of the comparison operators also work on strings and the addition operator also functions as a string concatenation operator see example below If you are not sure how NetLogo will interpret your code you should insert parentheses show 5 6 6 3 gt 32 show 5 6 6 3 gt 20 show tur tle gt turtle asin asin number Reports the arc sine inverse sine of the given number The input must be in the range 1 0 to 1 0 The result is in degrees and lies in the range 90 0 to 90 0 ask ask agentset commands ask agent commands The specified agent or agentset runs the given commands ask turtles fd 1 all turtles move forward one step ask patches set pcolor red all patches turn red ask turtle 4 rt 90 7 Only the turtle with id 4 turns right Note only the observer can ask all turtles or all patches This prevents you from inadvertently having all turtles ask all turtles or all patches ask all patches which is a common mistake to make if you re not careful about which agents will run the code you are writing Note Only the agents that are in the agen
340. the Command Center not followed by a carriage return unlike_print and show The lack of a carriage return allows you to print several values on the same line The calling agent is not printed before the value unlike_show type 3 type print 4 gt 3 4 See also print show and write See also output type U __untie untie leaf turile root turtle Disconnects eaf turtle from root turtle if they were previously tied together See also tie This command is part of the experimental Tie support in NetLogo See the Tie section of the Programming Guide for more details uphill uphill patch variable x Reports the turtle heading between 0 and 359 degrees in the direction of the maximum value of the variable patch variable of the patches in a one patch radius of the turtle This could be as many as eight or as few as five patches depending on the position of the turtle within its patch If there are multiple patches that have the same greatest value a random one of those patches will be selected If the patch is located directly to the north south east or west of the patch that the turtle is currently on a multiple of 90 degrees is reported However if the patch is located to the northeast northwest southeast or southwest of the patch that the turtle is currently on the direction the turtle would need Primitives Dictionary 287 NetLogo 3 1 4 User Manual to reach the nearest corner of that patch is report
341. the GUI e Can I have more than one model open at a time e Does NetLogo support multiple processors e Can distribute NetLogo model runs across a cluster of computers e Can use max pxcor or max pycor etc as the minimum or maximum of a slider e Can change the choices in a chooser on the fly e Can divide the code for my model up into several files e How do show the legend in a plot e Why does my code have strange characters in it BehaviorSpace e How do gather data every n ticks e I m varying a global variable declared in the Procedures tab but it doesn t work Why Programming e How is the NetLogo language different from the StarLogoT language How do convert my StarLogoT model to NetLogo e How does the NetLogo language differ from other Logos e My model from NetLogo 3 0 or earlier doesn t work or looks funny in 3 1 Help e Why do get a runtime error when use setxy random world width random world height It worked before e How do take the negative of a number e My turtle moved forward 1 but it s still on the same patch Why e patch ahead 1 is reporting the same patch my turtle is already standing on Why e How do give my turtles vision e Can agents sense what s in the drawing layer e Does NetLogo have a command like StarLogo s grab command e tried to put at after the name of a variable for example variable at 1 0 but NetLogo won t let me Why not e I m getting numb
342. the need to revise and expand the language so it is easier to use and more powerful and by the need to support the HubNet architecture NetLogo incorporates almost all of the extended functionality of our earlier StarLogoT as well as a great many newer features Has anyone built a model of lt x gt The best place to ask this question is on the NetLogo Users Group You should also check the Community Models section of our Models Library web page Are NetLogo models runs scientifically reproducible Yes NetLogo s agent scheduling algorithms are deterministic and NetLogo always uses Java s strict math library which gives bit for bit identical results regardless of platform But keep the following cautions in mind e If your model uses random numbers then in order to get reproducible behavior you must use the random seed command to set the random seed in advance so that your model will receive the exact same sequence of random numbers every time e If your model uses the every or wait commands in such a way that affects the outcome of the model then you may get different results on different computers or even on the same computer since the model may run at a different speed Such models are rare These two commands are common but using them in a way that affects the outcome is not 174 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual e In order to reproduce model runs exactly you must be using the exact same version
343. then drag the black handles in the selection border Deleting Select the element or elements you want to delete then press the Delete button on the Interface Toolbar You may also delete an element by control clicking Macintosh or right clicking other systems it and choosing Delete from the popup menu If you use this latter method it is not necessary to select the element first To learn more about the different kinds of interface elements refer to the chart below Chart Interface Toolbar Icon amp uc Button Buttons can be either once only buttons or forever buttons When you click on a once button it executes its instructions once The forever button executes the instructions over and over until you click on the button again to stop the action If you have assigned an action key to the button pressing the corresponding keyboard key will act just like a button press when the button is in focus Buttons with action keys have a letter in the upper right corner of the button to show what the action key is If the input cursor is in another interface element such as the Command Center pressing the action key won t trigger the button The letter in the upper right hand corner of the button will be dimmed in this situation To enable action keys click in the white background of the Interface tab 72 Interface Guide NetLogo 3 1 4 User Manual Sliders are global variables which are accessible by all agents They are
344. thored and developed by Kenneth Bradley Russell and Christopher John Kline 6 Copyright Information What s New Feedback from users is very valuable to us in designing and improving NetLogo We d like to hear from you Please send comments suggestions and questions to feedback ccl northwestern edu and bug reports to bugs ccl northwestern edu Version 3 1 4 February 16 2007 e installer now works on Windows Vista e improved models GasLab Circular Particles bugfix Small Worlds bugfix e Unicode characters are now supported when importing and exporting worlds e fixed bug where a too small 2D view could cause unusual behavior Version 3 1 3 September 20 2006 e fixed 3 1 2 only bug where exporting the world could cause a Java exception on Windows machines e fixed bug where saving a model didn t update the expected location of data files Version 3 1 2 August 9 2006 e documentation rewritten and expanded Tutorial 3 e models improved models 3D Shapes Example bugfix GasLab Single Collision improved code Tetris bugfix GasLab Circular Particles bugfixes added code for reversing time new Code Examples Musical Phrase Example Network Import Example e engine fixes fixed 3 1 only bug where startup procedures didn t work properly fixed 3 1 only bug where in radius in non wrapping worlds was slow fixed compiler bug where repeated lt breeds gt own declarations would not result in an error
345. tice this list of conditions and the following disclaimer e Redistribution in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution Neither the name of Sun Microsystems Inc or the names of contributors may be used to endorse or promote products derived from this software without specific prior written permission This software is provided AS IS without a warranty of any kind ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTIES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT ARE HEREBY EXCLUDED SUN MICROSYSTEMS INC SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES INNO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE PROFIT OR DATA OR FOR DIRECT INDIRECT SPECIAL CONSEQUENTIAL INCIDENTAL OR PUNITIVE DAMAGES HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES You acknowledge that this software is not designed licensed or intended for use in the design construction operation or maintenance of any nuclear facility Sun gratefully acknowledges that this software was originally au
346. ticular agents e drawing layer for marks left by turtles e buttons take turns now instead of interleaving their code with each other e more muted harmonious color palette e more attractive Information tab e GoGo extension for interfacing NetLogo with physical devices e Color Swatches dialog helps you choose colors e substantial improvements to BehaviorSpace e commands for importing image files e turtles can have cones of vision e expanded controlling API Version 2 1 December 2004 e much larger and higher quality library of turtle shapes e runs models headless with no GUI from the command line e editor now highlights matching parentheses and brackets e action keys let buttons be triggered by keypresses e makes QuickTime movies of models e redesigned Command Center for greater usability 10 What s New NetLogo 3 1 4 User Manual e optional output area in models e greatly improved shapes editor e easy capture of images from Interface tab e multilevel Undo in editor e new let command for easy creation of local variables e new carefully command for trapping runtime errors e computer HubNet substantially improved reliability server discovery is now fully supported you may serve multiple activities simultaneously from the same computer improved client interface and Control Center Version 2 0 2 August 2004 e new experimental extensions API lets users write new commands and reporters in Java e Net
347. tle 0 create link to turtle 1 create link from turtle 1 show __in link from turtle 1 prints turtle 3 show __out link to turtle 1 prints turtle 2 show __link with turtle 1 prints turtle 2 end This reporter is part of the experimental Links support in NetLogo See the Links section of the Programming Guide for more details 230 Primitives Dictionary NetLogo 3 1 4 User Manual in radius agentset in radius number 4 Reports an agentset that includes only those agents from the original agentset whose distance from the caller is less than or equal to number including the caller itself if wrapping is allowed by the topology members of the agentset within the radius using the wrapped distance will be included The distance to or a from a patch is measured from the center of the patch ask turtles ask patches in radius 3 set pcolor red 7 each turtle makes a red splotch around itself inspect inspect agent Opens an agent monitor for the given agent turtle or patch inspect patch 2 4 77 an agent monitor opens for that patch inspect one of sheep 77 an agent monitor opens for a random turtle from 7 the sheep breed int int number Reports the integer part of number any fractional part is discarded show int 4 7 gt 4 show int 3 5 gt 3 is agent is agentset is boolean is lt breed gt is link is list is number is patch is p
348. ts up the HubNet system HubNet must be started to use any of the other hubnet primitives with the exception of hubnet set client interface See the_HubNet Authoring Guide for details hubnet send hubnet send string tag name value hubnet send list of strings tag name value For Calculator HubNet this primitive acts in exactly the same manner as hubnet broadcast We plan to change this in a future version of NetLogo For Computer HubNet it acts as follows For a string this sends value from NetLogo to the tag tag name on the client that has string for its user name For a list of strings this sends value from NetLogo to the tag tag name on all the clients that have a user name that is in the list of strings Sending a message to a non existent client using hubnet send generates a hubnet exit message See the HubNet Authoring Guide for details Primitives Dictionary 225 NetLogo 3 1 4 User Manual hubnet send view hubnet send view string hubnet send view list of strings For Calculator HubNet does nothing For Computer HubNet it acts as follows For a string this sends the current state of the 2D view in the NetLogo model to the Computer HubNet Client with string for its user name For a list of strings this sends the current state of the view in the NetLogo model to all the Computer HubNet Clients that have a user name that is in the list of strings Sending the 2D view to a non existent client using hu
349. tset For each agent the reporter must report a patch agentset a single patch or nobody patches from turtles patch here 7 reports the set of all patches with turtles on them if there are many more patches than turtles this will 7 run much faster than patches with any turtles here See also turtles from patches own patches own var7 var2 This keyword like the globals breed lt breed gt own and turtles own keywords can only be used at the beginning of a program before any function definitions It defines the variables that all patches can use All patches will then have the given variables and be able to use them All patch variables can also be directly accessed by any turtle standing on the patch See also_globals turtles own breed lt breeds gt own Primitives Dictionary 257 NetLogo 3 1 4 User Manual pcolor pcolor E k This is a built in patch variable It holds the color of the patch You can set this variable to make the patch change color All patch variables can be directly accessed by any turtle standing on the patch See also color pen down pd pen erase pe pen up pu pen down pen erase pen up The turtle changes modes between drawing lines removing lines or neither The lines will always be displayed on top of the patches and below the turtles To change the color of the pen set the color of the turtle using set color Note When a turtle s pen is down all mo
350. tset ca crt 4 show values from turtles who gt 0 1 2 3 show values from turtles who who gt 0 1 4 9 variance variance list Reports the sample variance of a list of numbers Ignores other types of items The sample variance is the sum of the squares of the deviations of the numbers from their mean divided by one less than the number of numbers in the list show variance 2 7 4 3 5 gt 3 7 W wait wait number Wait the given number of seconds You can use floating point numbers to specify fractions of seconds Note that you can t expect complete precision the agent will never wait less than the given amount but might wait slightly more repeat 10 fd 1 wait 0 5 290 Primitives Dictionary NetLogo 3 1 4 User Manual See also_every watch watch agent Puts a spotlight on agent In the 3D view the observer will also turn to face the subject See also follow subject reset perspective watch me watch me watch me k Asks the observer to watch the calling agent See also watch while while reporter commands If reporter reports false exit the loop Otherwise run commands and repeat The reporter may have different values for different agents so some agents may run commands a different number of times than other agents while any other turtles here fd 1 7 turtle moves until it finds a patch that has 7 no other turtles on it who who k This
351. tset at the time the ask begins run the commands 196 Primitives Dictionary NetLogo 3 1 4 User Manual at points agentset at points x1 y1 x2 y2 Reports a subset of the given agentset that includes only the agents on the patches the given distances away from the calling agent The distances are specified as a list of two item lists where the two items are the x and y offsets If the caller is the observer then the points are measured relative to the origin in other words the points are taken as absolute patch coordinates If the caller is a turtle the points are measured relative to the turtle s exact location and not from the center of the patch under the turtle ask turtles at points 2 4 1 2 10 15 fa 1 7 only the turtles on the patches at the 7 distances 2 4 1 2 and 10 15 relative to the caller mov atan atan x y Reports the arc tangent in degrees from 0 to 360 of x divided by y When y is 0 if x is positive it reports 90 if x is negative it reports 270 if x is zero you get an error Note that this version of atan is designed to conform to the geometry of the NetLogo world where a heading of 0 is straight up 90 is to the right and so on clockwise around the circle Normally in geometry an angle of 0 is right 90 is up and so on counterclockwise around the circle and atan would be defined accordingly show atan 1 1 gt 135 0 show atan 1 1 gt 315 0 autoplot
352. tting the xcor or ycor of the root turtle When the root turtle turns right or left the leaf turtle is rotated around the root turtle the same amount The heading of the leaf turtle is also changed by the same amount See also untie This command is part of the experimental Tie support in NetLogo See the Tie section of the Programming Guide for more details 282 Primitives Dictionary NetLogo 3 1 4 User Manual timer timer Reports how many seconds have passed since the command reset timer was last run or since NetLogo started The potential resolution of the clock is milliseconds Whether you get resolution that high in practice may vary from system to system depending on the capabilities of the underlying Java Virtual Machine to to procedure name to procedure name input1 input Used to begin a command procedure to setup ca crt 500 end to circle radius ect 100 fd radius end to report to report procedure name to report procedure name input input2 Used to begin a reporter procedure The body of the procedure should use report to report a value for the procedure See_report to report average a b report a b 2 end to report absolute value number ifelse number gt 0 report number report number end to report first turtle report who 0 reports true or false end towards Primitives Dictionary 283 NetLogo 3 1 4 User Manual towards ag
353. tton Creating an experiment setup In the new dialog that appears you can specify the following information Note that you don t always need to specify everything some parts can be left blank or left with their default values depending on your needs Experiment name If you have multiple experiments giving them different names will help you keep them straight Vary variables as follows This is where you specify which settings you want varied and what values you want them to take Variables can include sliders switches choosers and any global variables in your model Variables can also include max pxcor min pxcor max pycor and min pycor world width world height and random seed These are not strictly speaking variables but BehaviorSpace lets you vary them as if they were Varying the world dimensions lets you explore the effect of world size upon your model Since setting world width and wor1d height does not necessarily define the bounds of the world how they are varied depends on the location of the origin If the origin is centered BehaviorSpace will keep it centered so the values world width or world height must be odd If one of the bounds is at zero that bound will be kept at zero and the other bound will move for example if you start with a world with min pxcor 0 max pxcor 10 and you vary world width like this rom lo zwi adtht ial ik aL J 128 BehaviorSpace Guide NetLogo 3 1 4 User Manual min pxcor wil
354. turtle sub menu Turtle and patch monitors can also be opened from the Tools menu or by using the inspect command Some NetLogo models let you interact with the turtles and patches with your mouse by clicking and dragging in the View Manipulating the 3D View At the bottom of the window there are buttons to move the observer or change the perspective from which you are looking at the world Rotate Zoom Move Interact Reset Perspective Full Screen Interface Guide 75 NetLogo 3 1 4 User Manual A blue cross appears at the current focus point as you are adjusting these settings The little blue triangle will always point up the positive y axis so you can orient yourself in case you get lost It s easy to do To look at the world from a different angle press the rotate button click and drag the mouse up down left or right The observer will continue to face the same point as before where the blue cross is but its position in the relation to the xy plane will change To move closer or farther away from the world or the agent you are watching following or riding press the zoom button and drag up and down along the 3D View Note when you are in follow or ride mode zooming will switch you between ride and follow since ride is just a special case of follow where the distance at which you are following is 0 To change the position of the observer without changing the direction it is facing select th
355. ual to 0 but strictly less than number If number is negative reports a random integer less than or equal to 0 but strictly greater than number If number is zero the result is always 0 as well Note In versions of NetLogo prior to version 2 0 this primitive reported a floating point number if given a floating point input This is no longer the case If you want a floating point answer you must now use random float instead show random 3 prints 0 TD OF 2 show random 3 ip prints 0 1 or 2 show random 3 0 pe prints 0 1 Ox 2 show random 3 5 pp prints 0 15 2 or 3 See also random float random float random float number If number is positive reports a random floating point number greater than or equal to 0 0 but strictly less than number If number is negative reports a random floating point number less than or equal to 0 0 but strictly greater than number If number is zero the result is always 0 0 show random float 3 7 prints a number at least 0 0 but less than 3 0 7 for example 2 589444906014774 show random float 2 5 262 Primitives Dictionary NetLogo 3 1 4 User Manual 7 prints a number at least 0 0 but less than 2 5 7 for example 1 0897423196760796 random exponential random gamma random normal random poisson random exponential mean random gamma alpha lambda random normal mean standard deviation random poisson mean Reports an accordingly distributed random number wit
356. ucible e Are there any NetLogo textbooks e Is NetLogo available in a Spanish version German version your language here version etc e Is NetLogo compiled or interpreted e Will NetLogo and NetLogo 3D remain separate Downloading e The download form doesn t work for me Can have a direct link to the software e Downloading NetLogo takes too long Is it available any other way such as on a CD e downloaded and installed NetLogo but the Models Library has few or no models in it How can fix this e Can have multiple versions of NetLogo installed at the same time e I m on a UNIX system and can t untar the download Why Applets e tried to run one of the applets on your site but it didn t work What should do e Can make my model available as an applet while keeping the code secret e Can a model saved as an applet use import world file open and other commands that read files Usage e Can run NetLogo from a CD e Why is NetLogo so much slower when unplug my laptop e How do change the number of patches FAQ Frequently Asked Questions 171 NetLogo 3 1 4 User Manual e Can use the mouse to paint in the view e How big can my model be How many turtles patches procedures buttons and so on can my model contain e Can import GIS data into NetLogo e My model runs slowly How can speed it up e want to try HubNet Can 1 e Can run NetLogo from the command line without
357. ude all possible colors It contains only certain discrete hues and for each hue either saturation or brightness may vary but not both at least one of the two is always 1 0 show hsb 0 0 0 gt 0 0 black show hsb 0 5 1 0 1 0 gt 85 0 cyan See also_extract hsb rgb extract rgb hubnet broadcast hubnet broadcast tag name value This broadcasts value from NetLogo to the variable in the case of Calculator HubNet or interface element in the case of Computer HubNet with the name tag name to the clients See the_HubNet Authoring Guide for details and instructions hubnet broadcast view hubnet broadcast view This broadcasts the current state of the 2D view in the NetLogo model to all the Computer HubNet Clients It does nothing for Calculator HubNet Note This is an experimental primitive and its behavior may change in a future version See the_HubNet Authoring Guide for details and instructions Primitives Dictionary 223 NetLogo 3 1 4 User Manual hubnet enter message hubnet enter message Reports true if a new computer client just entered the simulation Reports false otherwise hubnet message source will contain the user name of the client that just logged on See the_HubNet Authoring Guide for details and instructions hubnet exit message hubnet exit message Reports true if a computer client just exited the simulation Reports false otherwise hubnet message source will contain the user
358. umber2 number2 show remainder 62 5 gt 2 show remainder 8 3 gt 2 See also_mod mod and remainder behave the same for positive numbers but differently for 266 Primitives Dictionary NetLogo 3 1 4 User Manual negative numbers remove remove tem list remove string1 string2 For a list reports a copy of list with all instances of tem removed For strings reports a copy of string2 with all the appearances of string1 as a substring removed set mylist 2 7 4 7 Bob set mylist remove 7 mylist 7 mylist is now 2 4 Bob show remove na banana gt ba remove duplicates remove duplicates list Reports a copy of list with all duplicate items removed The first of each item remains in place set mylist 2 7 4 7 Bob 7 set mylist remove duplicates mylist 5 mylist is now 2 7 4 Bob remove item remove item index list remove item index string For a list reports a copy of list with the item at the given index removed For strings reports a copy of string2 with the character at the given index removed Note that the indices begin from 0 not 1 The first item is item 0 the second item is item 1 and so on set mylist 2 7 4 7 Bob set mylist remove item 2 mylist 7 mylist is now 2 7 7 Bob show remove item 3 banana gt banna __remove lt breed gt from __remove lt breed gt to __remove lt breed gt with Primitives Dictionary 267 NetLogo 3 1 4 User Manual __
359. up startup io User defined procedure which if it exists will be called when a model is first loaded to startup setup end 280 Primitives Dictionary NetLogo 3 1 4 User Manual stop stop The calling agent exits immediately from the enclosing procedure ask or ask like construct cct hatch sprout Only the current procedure stops not all execution for the agent Note stop can be used to stop a forever button If the forever button directly calls a procedure then when that procedure stops the button stops In a turtle or patch forever button the button won t stop until every turtle or patch stops a single turtle or patch doesn t have the power to stop the whole button subject subject Reports the turtle or patch that the observer is currently watching following or riding Reports nobody if there is no such turtle or patch See also_watch follow ride sublist substring sublist list position position2 substring string position position2 Reports just a section of the given list or string ranging between the first position inclusive and the second position exclusive Note The positions are numbered beginning with 0 not with 1 show sublist 99 88 77 66 1 3 gt 88 77 show substring turtle 1 4 gt urt subtract headings subtract headings heading1 heading2 Computes the difference between the given headings that is the number of degrees in the smallest angle by whic
360. uption xor World primitives clear all ca clear drawing cd clear patches cp clear turtles ct display import drawing import pcolors no display max pxcor max pycor min pxcor min pycor world width world height Perspective primitives follow follow me reset perspective rp ride ride me subject watch watch me HubNet primitives hubnet broadcast hubnet broadcast view hubnet enter message hubnet exit message hubnet fetch message hubnet message hubnet message source hubnet message tag hubnet message waiting hubnet reset hubnet send hubnet send view hubnet set client interface Input output primitives beep clear output date and time export view export interface export output export plot export all plots export world import drawing import pcolors import world mouse down mouse inside mouse xcor mouse ycor output print output show output type output write print read from string reset timer set current directory show timer type user directory user file user new file user input user message user one of user yes or no write File primitives fle at end file close file close all file delete file exists file open file print file read file read characters file read line file show file type file write user directory user file user new file List primitives but first but last empty filter first foreach fput is list item last length list lout map member modes n of n values position one of reduce remove remove
361. urtles point outwards If the first input is an agentset the turtles are arranged in random order If the first input is a list the turtles are arranged clockwise in the given order starting at the top of the circle Any non turtles in the list are ignored 7 in random order layout circle turtles 10 7 in order by who number __layout circle sort turtles 10 7 in order by size layout circle sort by size of 1 lt size of 2 turtles 10 __layout magspring __layout magspring agentset anchor agentset spring constant spring length repulsion constant magnetic field strength magnetic field type bidirectional Very similar to__layout spring but with an added layer of complexity The agentset of turtles attract and repel each other depending on the links between them but there is also a magnetic field which the links try to align with anchor agentsetis a set of turtles whose positions remain fixed If no turtles are anchored down then they will often all slide off to the side of the view spring constant is a measure of the tautness of the spring See___layout spring spring length is the zero force length or the natural length of the springs See___layout spring repulsion constant is a measure of repulsion between the nodes See___layout spring magnetic field strength is the force of the magnetic field Reasonable values range from 0 0 to 1 0 but 0 05 is a good default magnetic field type is a nu
362. urtles to connect their movement to another turtle See the Tie Section of the Programming Guide for details e other language changes the sort and sort by primitives can now be used to convert an agentset to a sorted list of agents if you use sort turtles are sorted by who number and patches are sorted left to right top to bottom new reporters random xcor random ycor random pxcor and random pycor are handy for generating random coordinates 4 member can now be used to check whether an agent is a member of an agentset worked in 3 0 but was undocumented 4 random one of and random n of have been renamed to just one of and n of removed no label from the language use the empty string instead renamed user choice to user one of user choose file to user file user choose new file to user new file user choose directory to user directory e interface changes minor improvements to look amp feel e g vertical buttons in toolbars instead of horizontal ones the info tabs of saved applets are now more attractive as in the application 4 user one of formerly user choice now always shows the choices as a menu never buttons e engine fixes fixed 3 0 only bug where the repeat and let commands didn t always work correctly when used from the Command Center in the System Dynamics Modeler system dynamics t is now incremented at the end of each step not the beginning o What s New 9 NetLogo 3 1 4 User
363. use it on you will have to use NetLogo 1 3 1 to do the converting then open the model in a current version If you need any help converting your StarLogo or StarLogoT model to NetLogo please feel free to seek help on the_NetLogo Users Group You may also ask us for help at feedback ccl northwestern edu 182 FAQ Frequently Asked Questions NetLogo 3 1 4 User Manual How does the NetLogo language differ from other Logos There is no standard definition of Logo it is a loose family of languages We believe that NetLogo shares enough syntax vocabulary and features with other Logos to earn the Logo name Still NetLogo differs in some respects from most other Logos The most important differences are as follows Surface differences e The precedence of mathematical operators is different Infix math operators like etc have lower precedence than reporters with names For example in many Logos if you write sin x 1 it willbe interpreted as sin x 1 NetLogo on the other hand interprets it the way most other programming languages would and the way the same expression would be interpreted in standard mathematical notation namely as sin x 1 e The and and or reporters are special forms not ordinary functions and they short circuit that is they only evaluate their second input if necessary e Procedures can only be defined in the Procedures tab not interactively in the Command Center e Reporter procedures tha
364. ut area or the output section of he command center to a file im port World Load a file that was saved by Export World Import Patch Colors Load an image into the patches see the impori pcolors ommand Import Drawing Load an image into the drawing see the import drawing ommand Quit Exits NetLogo On Macs this item is on the NetLogo menu instead Cut Cuts out or removes the selected text and temporarily saves it o the clipboard P u Copy Copies the selected text aste Places the clipboard text where cursor is currently located Delete _ Deletes selected text o Undo Undo last text editing action you performed Redo Redo last undo action you performed Select All Select all the text in the active window Find Finds a word or sequence of characters within the Information or Procedures tabs used Find with Shift Right ode Comment Used in the Procedures tab to add or remove semicolons from Uncomment ode semicolons are used in NetLogo code to indicate Halt Stops all running code including buttons and the command enter Warning since the code is interrupted in the middle of hatever it was doing you may get unexpected results if you ry to continue running the model without first pressing setup o start the model run over Globals Monitor Turtle Monitor Displays the values of all of the variables in a particular turtle ou can can also edit the values of the turtle s variable
365. uttons are only started when you press them Synchronization In both StarLogoT and NetLogo commands are executed asynchronously each turtle or patch does its list of commands as fast as it can In StarLogoT one could make the turtles line up by putting in a comma At that point the turtles would wait until all were finished before any went on The equivalent in NetLogo is to come to the end of an ask block If you write it this way the two steps are not synced ask turtles fd random 10 do stuff Since the turtles will take varying amounts of time to move they ll begin do stuff at different times But if you write it this way they are ask turtles fd random 10 ask turtles do stuff Programming Guide 97 NetLogo 3 1 4 User Manual Here some of the turtles will have to wait after moving until all the other turtles are done moving Then the turtles all begin do stuff at the same time This latter form is equivalent to this use of the comma in StarLogoT fd random 10 do stuff Lists In the simplest models each variable holds only one piece of information usually a number or a string The list feature lets you store multiple pieces of information in a single variable by collecting those pieces of information in a list Each value in the list can be any type of value a number or a string an agent or agentset or even another list Lists allow for the convenient packaging of information in NetL
366. vement commands cause lines to be drawn including jump and setxy Note These commands are equivalent to setting the turtle variable pen mode to down up and erase Note On Windows drawing and erasing a line might not erase every pixel pen mode k This is a built in turtle variable It holds the state of the turtle s pen You set the variable to draw lines erase lines or stop either of these actions Possible values are up down and erase pen size 258 Primitives Dictionary NetLogo 3 1 4 User Manual x This is a built in turtle variable It holds the width of the line in pixels that the turtle will draw or erase when the pen is down or erasing plabel plabel k This is a built in patch variable It may hold a value of any type The patch appears in the view with the given value attached to it as text You can set this variable to add change or remove a patch s label All patch variables can be directly accessed by any turtle standing on the patch See also plabel color label label color plabel color plabel color This is a built in patch variable It holds a number greater than or equal to O and less than 140 This number determines what color the patch s label appears in if it has a label You can set this variable to change the color of a patch s label All patch variables can be directly accessed by any turtle standing on the patch See also plabel label label co
367. versions were provided for distance xy in radius in cone face xy and towards xy In 3 1 the special no wrap versions are no longer necessary Instead the topology controls whether the primitives wrap or not They always use the shortest path allowed by the topology For example the distance from the center of the patches in the bottom right corner min pxcor min pycor and the upper left corner max pxcor max pycor will be as follows for each topology given that the min and max pxcor and pycor are 2 e Torus sqrt 2 1 414 this will be the same for all world sizes since the patches are directly diagonal to each other in a torus e Box sqrt world width 2 world height 2 7 07 e Vertical Cylinder sart world height 2 1 5 099 e Horizontal Cylinder sqrt world width 2 1 5 099 All the other primitives will act similarly to distance If you formerly used no wrap primitives in your model we recommend removing them and changing the topology of the world instead There are a number of reasons to change your model to use topologies rather than no wrap primitives First we expect if you are using no wrap primitives you are actually modeling a world that is not a torus If you use a topology that matches the world you are modeling NetLogo does automatic bounds checking for you it should make your life easier your code simpler to understand and it adds visual cues to help the model user understand w
368. view both send the entire View to the clients instead of just the patches that need to be redrawn This makes them less efficient but for some models this is feature is necessary To send the View to the clients using this scheme you must use the following NetLogo code hubnet broadcast view to send to all the logged in clients To just send the View to a subset of all the clients use hubnet send view user name list where user name liist is either a single string or a list of strings of the user names of clients that you want to send it to 146 HubNet Authoring Guide NetLogo 3 1 4 User Manual If there is no View in the clients or if the Mirror View on Clients checkbox in the HubNet Control Center is not checked then no view messages are sent to the clients NOTE Since hubnet broadcast view and hubnet send view are experimental primitives their behaviors may change in a future release Note Some of the View features in NetLogo are not yet implemented on the HubNet clients such as View Wrapping and Observer Perspectives Plot Updates on the Clients When a plot in the NetLogo model changes and a plot with the exact same name exists on the clients a message with that change is sent to the clients causing the client s plot to make the same change For example let s pretend there is a HubNet model that has a plot called Milk Supply in NetLogo and the clients Milk Supply is the current plot in NetLogo and in the Comma
369. w and file type filter filter reporter list Reports a list containing only those items of list for which the boolean reporter is true in other words the items satisfying the given condition In reporter use to refer to the current item of list show filter lt 3 1 3 2 gt 1 2 show filter first t hi there everyone gt hi everyone See also_map reduce _ first first list first string On a list reports the first Oth item in the list On a string reports a one character string containing only the first character of the original string floor floor number Reports the largest integer less than or equal to number show floor 4 5 gt 4 218 Primitives Dictionary NetLogo 3 1 4 User Manual show floor 4 5 gt 5 follow follow turtle gt Similar to ride but in the 3D view the view is behind and above turtle See also _follow me ride reset perspective watch subject follow me follow me Asks the observer to follow the calling turtle See also follow foreach foreach list commands foreach list listn commands With a single list runs commands for each item of list In commands use to refer to the current item of list foreach 1 1 2 2 2 6 show gt round With multiple lists runs commands for each group of items from each list So they are run once for the first items once f
370. w command This is used in some other Logos to let the turtle roam over an infinite plane e There is no flood or fill command to fill an enclosed area with color Topology The topology of the NetLogo world has four potential values torus box vertical cylinder or horizontal cylinder The topology is controlled by enabling or disabling wrapping in the x or y directions The default world is a torus as were all NetLogo worlds before NetLogo 3 1 A torus wraps in both directions meaning that the top and bottom edges of the world are connected and the left and right edges are connected So if a turtle moves beyond the right edge of the world it appears again on the left and the same for the top and bottom A box does not wrap in either direction The world is bounded so turtles that try to move off the edge of the world cannot Note that the patches around edge of the world have fewer than eight neighbors the corners have three and the rest have five Horizontal and vertical cylinders wrap in one direction but not the other A horizontal cylinder wraps vertically so the top of the world is connected to the bottom but the left and right edges are bounded A vertical cylinder is the opposite it wraps horizontally so the left and right edges are connected but the top and bottom edges are bounded Code Example Neighbors Example Since NetLogo 3 0 there have been settings to enable wrapping visually so if a turtle shape extends past an edge
371. w squares than special shapes so the model runs faster The freeze button freezes the view The model continues to run in the background and plots and monitors still update but if you want to see what s happening you need to unfreeze the view by turning the switch back on Most models run much faster when the view is frozen The size of the view is determined by three separate settings X Edge Y Edge and Patch Size Let s take a look at what happens when we change the size of the view in the Wolf Sheep Predation model There are more world and view settings than there s room for in the control strip The Edit button lets you get to the rest of the settings e Press the Edit button in the control strip A dialog box will open containing all the settings for the view 32 Tutorial 1 Models NetLogo 3 1 4 User Manual 000 World amp View World Location of origin Center a minimum x coordinate for patches max pxcor 17 maximum x coordinate for patches minimum y coordinate for patches max pycor 17 Torus 35 x 35 maximum y coordinate for patches vi World wraps horizontally M World wraps vertically View Patch size pixels 12 0 Font size of turtle and patch labels 10 Y Turtle shapes Y Smooth edges slower only affects 3D view Cancel Apply Cok What are the current settings for max pxcor min pxcor max pycor min pycor and Patch size e Press cancel to mak
372. x If you re doing very long model runs you might not want all that data Uncheck this box if you only want to measure each run after it ends Setup commands These commands will be used to begin each model run Typically you will enter the name of a procedure that sets up the model typically setup But it is also possible to include other commands as well Go commands These commands will be run over and over again to advance to the model to the next tick Typically this will be the name of a procedure such as go but you may include any commands you like Stop condition This lets you do model runs of varying length ending each run when a certain condition becomes true For example suppose you wanted each run to last until there were no more turtles Then you would enter not any turtles If you want the length of runs to all be of a fixed length just leave this blank The run may also stop because the go commands use the stop command in the same way that stop can be used to stop a forever button The stop command may be used directly in the go commands or in a procedure called directly by the go commands The intent is that the same go procedure should work both in a button and in a BehaviorSpace experiment Note that the step in which stop is used is considered to have been aborted so no results will be recorded for that step Therefore the stopping test should be at the beginning of the go commands or procedure not at the e
373. xcor min pycor and max pycor are 17 17 17 and 17 respectively This means that pxcor and pycor both range from 17 to 17 so there are 35 times 35 or 1225 patches total You can change the number of patches by editing NetLogo s view Turtles have coordinates too xcor and ycor A patch s coordinates are always integers but a turtle s coordinates can have decimals This means that a turtle can be positioned at any point within its patch it doesn t have to be in the center of the patch The world of patches can have different shapes By default the world is a torus which means it isn t bounded but wraps so when a turtle moves past the edge of the world it disappears and reappears on the opposite edge and every patch has the same number of neighbor patches if you re a patch on the edge of the world some of your neighbors are on the opposite edge However you can change the shape of the world by adjusting the wrap settings by editing the view If wrapping is not allowed in a given direction then in that direction x or y the world is bounded Patches along that boundary will have fewer than 8 neighbors and turtles will not move beyond the edge of the world See the Topology section for more information Procedures In NetLogo commands and reporters tell agents what to do A command is an action for an agent to carry out A reporter computes a result and report it Most commands begin with verbs create die jump
374. y cannot interact with or process images imported by import drawing If you need agents to sense an image use import pcolors The following image file formats are supported BMP JPG GIF and PNG If the image format supports transparency alpha that information will be imported as well import pcolors import pcolors filename io Reads an image file scales it to the same dimensions as the patch grid while maintaining the original aspect ratio of the image and transfers the resulting pixel colors to the patches The image is centered in the patch grid The resulting patch colors may be distorted since the NetLogo color space does not include all possible colors See the Color section of the Programming Guide import pcolors may be slow for some images particularly when you have many patches and a large image with many different colors Since import pcolors sets the pcolor of patches agents can sense the image This is useful if agents need to analyze process or otherwise interact with the image If you want to simply display a static backdrop without color distortion see_import drawing The following image file formats are supported BMP JPG GIF and PNG If the image format supports transparency alpha then all fully transparent pixels will be ignored Partially transparent pixels will be treated as opaque import world 228 Primitives Dictionary NetLogo 3 1 4 User Manual import world filename Reads the values
375. yfile txt print file at end gt false Can still read in more characters print file read line gt This is the last line in file print file at end gt true We reached th nd of the file See also file open file close all file close file close Closes a file that has been opened previously with file open Note that this and file close all are the only ways to restart to the beginning of an opened file or to switch between file modes If no file is open does nothing See also file close all file open file close all file close all Closes all files if any that have been opened previously with file open See also file close file open file delete file delete string Deletes the file specified as string string must be an existing file with writable permission by the user Also the file cannot be open Use the command file close to close an opened file before deletion Note that the string can either be a file name or an absolute file path If it is a file name it looks in whatever the current directory is This can be changed using the command set current directory It is defaulted to the model s directory 214 Primitives Dictionary NetLogo 3 1 4 User Manual file exists file exists string Reports true if string is the name of an existing file on the system Otherwise it reports false Note that the string can either be a file name or an absolute file path If it is a file name it looks
376. you will be able to see relationships form between different sliders and the behavior of the system After all the runs are over a dataset is generated which you can open in a different tool such as a spreadsheet database or scientific visualization application and explore By enabling you to explore the entire space of behaviors a model can exhibit BehaviorSpace can be a powerful assistant to the modeler BehaviorSpace Guide 127 NetLogo 3 1 4 User Manual Historical Note Old versions of NetLogo prior to 2 0 included an earlier version of the BehaviorSpace tool That version was much different lt wasn t nearly as flexible in the kinds of experiments it let you set up But it had facilities for display and analyzing experiment results that are missing from the current version With the current version it is assumed that you will use other software to analyze your results We hope to re add data display and analysis facilities to a future version of BehaviorSpace How lt Works To begin using BehaviorSpace open your model then choose the BehaviorSpace item on NetLogo s Tools menu Managing experiment setups The dialog that opens lets you create edit duplicate delete and run experiment setups Experiments are listed by name and how by model runs the experiment will consist of Experiment setups are considered part of a NetLogo model and are saved as part of the model To create a new experiment setup press the New bu
377. your model or give us some idea of how it works The members of the NetLogo Users Group may be able to help as well want to try HubNet Can I Yes There are two types of HubNet available With Computer HubNet participants run the HubNet Client application on computers connected by a regular computer network In Calculator HubNet created in conjunction with Texas Instruments participants use Tl 83 graphing calculators and the Tl Navigator Classroom Learning System Note that Calculator HubNet works with a prototype version of the Tl Navigator system and is not yet compatible with the commercially available TI Navigator We are actively working in partnership with Texas Instruments on integrating the new TI Navigator with Calculator HubNet which we expect to release in the near future For more information on HubNet see the HubNet Guide Can I run NetLogo from the command line without the GUI Yes The easiest way is to set up your model run as a BehaviorSpace experiment No additional programming is required See the BehaviorSpace section of the User Manual for details Another option is to use our Controlling API Some light Java programming is required See the Controlling section of the User Manual for details and sample code Can I have more than one model open at a time One instance of NetLogo can only have one model open at a time We plan to change this ina future version You can have multiple models open by open
378. yself myself E ka self and myself are very different self is simple it means me patch who asked me to do what I m doing right now myself means the turtle or When an agent has been asked to run some code using myself in that code reports the agent turtle or patch that did the asking myself is most often used in conjunction with of to read or set variables in the asking agent myself can be used within blocks of code not just in the ask command but also hatch sprout values from value from turtles from patches from histogram from with min one of and max one of ask turtles ask patches in radius 3 set pcolor color of myself 7 each turtle makes a colored splotch around itself See the Myself Example code example for more examples See also_self Primitives Dictionary 247 NetLogo 3 1 4 User Manual N n of n of size agentset From an agentset reports an agentset of size size randomly chosen from the input set with no repeats From a list reports a list of size size randomly chosen from the input set with no repeats The items in the result appear in the same order that they appeared in the input list If you want them in random order use shuffle on the result It is an error for size to be greater than the size of the input ask n of 50 patches set pcolor green 7 50 randomly chosen patches turn green See also one of n values n values size reporter

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