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Agent Based Simulator

1. Now let s try running it Try displaying the Control Panel window Notice how the range has changed to from 50 to 500 for just the number of red ants So how does this change affect the simulation Try running it yourself and see 1 3 Constructing a Simple Model In this section you ll learn about the basic elements and procedures for constructing an agent model from a completely blank state Construction of a model usually follows a sequence like the one described following 1 8 Agent Based Simulator User s Manual Segregation ABS File Edit View Add Settings Run Playback Window Help Ose sels Control Panel E INFORMATION a ao s00 HAPPINESS LIMIT HAPPINESS asooo UNHAPPY HAPPY Simulating 1 Component placement and settings 2 Output settings 3 Describing agent rules 4 Running and debugging This list comes up many times during the creation process so use it to get a general idea of what operation you re performing at the time This section also deals with the important programming concepts of conditional branches If statements methods of setting initial values and debugging Rules are still at an undeveloped stage but beginners should familiarize themselves with the unique modes of expression and Control Panel List of user settings Agent Based Simulator User s Manual 1 9 ways of writing that are used in programming If you already have a certain lev
2. Agent Based Simulator User s Manual 2 13 This dialog box appears when you go to the Tree window select Two dimensional Space then go into the Settings menu and choose Initialize You place agents and variables by click ing any coordinates in Space Two dimensional Space important When you display this dialog box in the initial state all the agents may be bunched together in the upper left corner If this happens click the Clear Screen button to reset the screen Doing this eliminates the placed agents Make sure the agents are gone from the space then click where you want to place the agents In order to place multiple agents at one location enter the numerical value in Range of Change Setting Target Select the agent or variable to be placed on the two dimensional space Number of Agents This sets the number of agents to be placed at the point you select by clicking with the mouse If you have chosen Select with Mouse described later then the numerical value set for Range of Change is automatically entered If you have chosen a variable for Setting Target this field changes to Initial Value Total Number of Agents Maximum Number The value set for Number of Agents in Properties automatically appears in the Maximum Number field and the present number of placed agents automatically appears in the Total Number of Agents field If you have chosen a variable for Setting Target these do not appear
3. Control Panel xj Once the button is clicked it remains ON D gt I E Toggle Button Used GROWTH RATE The button is ON when clicked once and switched OFF j 1 4 when clicked a second time SEASON Slider Used RED ANT By dragging with the mouse you can change the value freely within the Range entered in the Control Panel Settings dialog BLUE_ANT box 30 200 Direct Entry Used Click to select then type a value directly from the keyboard Agent Based Simulator User s Manual 2 31 2 4 Log Playback Feature To use this feature you must first make settings run a simulation and generated a log file When you open the log file you can replay the simulation When you do this the Playback menu becomes available for selection Selecting Run in this state displays the Playback panel and replays the simulation File Edit View Add Settings Run Playback Window Help D Shl mtela Replay Panel x gt wif a os RunNo StepO Date 00708720 00 08 20 00 08 20 00 08 20 00 08 20 00 08 20 00 08 20 00 08 20 14 48 35 00 08 20 14 48 35 007 08 20 14 48 36 w es o w o upan ponroa RED ANT i BLUE ANT Playback button This button performs continuous playback to the end Step Playback button Each click of this button plays back one step Pause button Clicking this during playback pauses the playback Stop button This button stops playb
4. by Var sTaTUS Var 7 Teepeeerine Indicate Set Map Name and Map Title to Two dimensional Space At the Map Component List click Add to add the component When the Two dimensional Map Component Settings dialog box appears set Component Name to Tree and set Output Target to Tree as well Leave Marker View blank unselected set Agent Color to Set by Variable and select State Leave Agent Variable Information unselected When you ve finished making the settings close the Output Item List dialog box Making the Settings for the Control Panel Window From the menu bar select the Settings menu and choose Control Panel Settings When the Control Panel window s User Setting List dialog box appears click Add User Setting Component Control DENSITY_wooDs Target DENsTTY_woops Cancel Interface C Button C Toggle Range 20 to 100 Spacing fa Slide Bar C Input Agent Based Simulator User s Manual A 21 When the User Settings dialog box appears set Control Name to treeDensity and Setting Target to treeDensity as well For Interface choose Slider Set Range to 20 to 100 and Scale Interval to 1 When you ve finished making the settings click OK to close the window The User Setting List dialog box closes Writing the World Rule Write the following rule for the World agent This is not used here as the initial rule The rule first obtains the size of the space then calculates the number of a
5. 3 _xxx The number of function arguments does not match the function specification Call x arguments Function specification y arguments Remedy Check for an error in the format of the arguments 4 xx is required after Remedy Make sure that Xx exists after 3 18 Agent Based Simulator User s Manual Appendix Creating More Advanced Models The interesting thing about multi agent models is that they affect each other based on local information Local information could also be termed limited information around the agents themselves For instance even in our real lives we depend on limited information around ourselves to act and make decisions on a day to day basis We also learn about events occurring elsewhere through the media and from other people In simulations using earlier programming languages however it was rather difficult to produce such local interactions Agent Based Simulator was designed for manipulating agents so you can program local interaction fairly easily However you still need to know some procedures and methods This chapter describes some expressions that are unique to Agent Based Simulator Give them a try even if you already have experience with Visual Basic or the like Because this chapter uses simple explanations that omit the descriptions of on screen procedures in earlier chapters if you re not sure about a procedure go back to the previous chapters to check it A 1 A M
6. Marker Color These set the type and color of the markers indicating agents and variables in the two dimensional space Select with Mouse When you select this check box then each time you click the coordinate the number of components increases or decreases by the amount set for Range of Change File Input File Output You can import the initial values from an existing file or save them in a file by clicking these buttons Display List Selected components appears on Space Two dimensional Space Initialize Dialog Box for Agents and Variables You can set the initial values of agents and variables that are used when the simulation starts To display this dialog box select an agent or a variable in Tree window then go into the Settings menu and choose Initialize 2 14 Agent Based Simulator User s Manual lnitial Value Agent initialize RED_ANT RED_ANT X Y VIEW STOMACH DIRECTION ENERGY a D 0 0000 0 0000 3 4 0000 0 0000 0 E 1 0 0000 0 0000 3 4 0000 0 0000 0 2 0 0000 0 0000 3 4 0000 0 0000 0 3 0 0000 0 0000 3 4 0000 0 0000 0 4 0 0000 0 0000 3 4 0000 0 0000 0 5 0 0000 0 0000 3 4 0000 0 0000 0 6 0 0000 0 0000 3 4 0000 0 0000 D 0 0000 0 0000 3 4 0000 0 0000 0 8 0 0000 0 0000 3 4 0000 0 0000 0 9 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3
7. One For i 0 To 10 For i 0 To 10 For Next Nee i eel X Variable i required at end i Comments L ass ere IP Seg 8 Agt_Init Executed once when created Special functions Agt_Step Executed at every step Agent Based Simulator User s Manual 1 29 Chapter 2 Reference 2 1 Making Settings for Models This section describes the features for making model settings including agents variables and other components 2 1 1 Job File Input and Output Select one of the commands from the File menu in the following figure to create a new simulation import an existing job file or save the settings for a simulation you have created The setting data for a simulation is saved as a job file abs Creating a New Job To make settings for a new simulation from the File menu select New or click the New button on the tool bar Saving a Job File To save a job file for which you have made settings from Open Ctri O Glose Save Gtri S Saye As ABS Client Print Gtrl P Print Preview Print Setup Exit ABS File Edit View Add Settin the File menu select Save or Save As or click the Save button on the tool bar 2 2 Agent Based Simulator User s Manual 2 1 2 Creating a New Job File When you start Agent Based Simulator and create a new job file the following screen appears Untitled ABS File Edit View Add Settings Run Playback Window Help eh mtgal Canvas
8. forest e ABS File Edit View Add Settings Run Playback Window Help Dah tases two dimensional map Number output parameter LOST WOODS 473 RATE LOST WOODS 25 6 Simulating fot tre seat a 7 Agent Based Simulator User s Manual A 33 Index and Infomation Index A E Agent 0 2 1 11 Edge of space 2 5 properties 2 6 Else statement A 7 adding 1 12 2 6 _ExitSimulation A J 3 function 3 14 Expression 3 8 rule 0 3 F destroying 2 10 File individually set 2 15 output settings 2 23 Find future 2 8 Font settings 2 9 For statement 1 23 3 10 For Each statement A 23 Forest fire model A 18 initialize dialog 2 14 new 2 3 variable information A 5 Agt_Init 3 2 Agt_Step 3 2 Argument 3 9 Function Assignment statement 3 7 iser defied 3 3 A tomatie indent 72 2 Function statement 3 3 B important note on naming 1 27 Backup variable A 24 user defined 1 27 Bar graph G output settings 2 19 GetCountStep A 26 Break statement 3 11 Gdtost atemehi 3 11 g H Canvas 1 10 2 3 Help 9 40 CdblQ A 28 _CollectAround A 23 I Collection If statement 1 17 function 3 14 Initialize how to use type variable A 18 two dimensional space 2 13 Comments 3 17 J Common rule editor 1 22 Job file Conditional statement 3 9 creating new 2 2 Control panel 1 3 1 5 1 11 saving 2 2 setting 2 29 A 8 L _CountAgent 1 23 Log _CreateAgent A Il file tab 2 26 D playi
9. z al To make the settings for x z Type to Add in this dialog box choose a graph or Add Edit Delete file then click Add Add to Output Items As If multiple outputs are required you need to add the output methods The series of Output Items settings change to Move Icons To change visible unvisible selects to View check box Time series Graph Output Settings Time series graph displays components as a time series line To make settings this graph select Time series Graph in Output Type to Add field 2 16 Agent Based Simulator User s Manual Time Series Graph Setting a xj Name time series graph 1l Graph Cancel Exp Notes v Setting of X Axis Setting of Y Axis Axis Axis Max Indicate 1000 Max Spacing fo Spacing Graph Component List Add Edit Delete Name This is the name referenced when calling up this graph Title This title appears on the graph displayed on the output screen Show Legend When you select this check box a legend is displayed next to the graph Axis Label When the graph is displayed this item is also displayed as the label for the axis Minimum Value Maximum Value Scale Interval These specify the minimum value the maximum value and the interval of the scale for the displayed graph Maximum Number of Displayed Steps With each step the time series graph is displayed in a compressed form Wh
10. Examples Function Function2 a as Integer b As Integer c As Double As Integer Sub Function2 a as Integer b As Integer c As Double Differences between Function and Sub When a user defined function is executed if you want to use the value of the result the return value directly in an execution statement use Function In other cases use Sub For example Agt_Step Dima As Integer a Function1 5 3 Function Function1 b As Integer c As Integer As Integer Dim answer As Integer Answerl b c Return answer1 In line 2 we declare variable a of Integer data type Next we pass the values 5 and 3 to the user defined function Functionl and assign its calculation result to a In the user defined function starting at line 5 we declare the variable answerl of Integer data type line 6 assign the calculation result of b c in this case 5 3 to answerl line 7 then return the value of answerl to the Function location in Agt_Step That is this example says to assign the answer of the calculation of 5 3 to the variable a However if it s not necessary to assign the calculation result to the a variable then there is no need for the user defined function to return a value In such cases use Sub instead of Function 3 4 Rules for Names The names of variables and functions used in agent rules must follow the convention below The first character of a name must be a letter e Each of the second
11. Rewriting the Rules Rewrite the necessary portions of the respective rules for the red turtles and blue turtles to reference the variable you just created If my happiness lt 0 6 Then _MoveToSpace my X my Y 3 EndIf Change the portions with this constant as follows If my happiness lt World threshold Then _MoveToSpace my X my Y 3 EndIf Agent Based Simulator User s Manual A 9 Making the Settings for the Control Panel Window From the menu bar select the Settings menu and choose Control Panel Settings When the Control Panel window s User Setting List dialog box appears click Add User Setting Component Target imr Hao Interface C Button Toggle Range 0 2 tofo 8 Spacing fo os Slide Bar C Input When the User Settings dialog box appears set Control Name to Threshold and Setting Target to Threshold For Interface choose Slider Set Range to 0 2 to 0 8 and Scale Interval to 0 05 When you ve finished making the settings click OK to close the window The User Setting List dialog box closes gt Create variables to be manipulated with the Control Panel window directly under the World hierarchy A 2 2 Making It Possible to Change the Starting Number of Turtles With the simple segregation model it s necessary to set the starting number of turtles in advance with Agent Properties However this means that in order to investigate changes due to an increase or decr
12. WORLD os Select New Space Ss New Agent ea New Var Tree This is the most basic screen for this simulator It displays the hierarchical structure of the various components One agent the World agent always exists in the tree Create other components such as two Dimensional space agents and variables under it and make up the settings for the simulation Canvas This is a window that only agents can have To display it first select an agent in the Tree window then go into the View menu and select Canvas or double click the agent You can use this window to place child agents and variables Toolbox You use this when placing child agents variables spaces and the like on the Canvas Spaces can be placed only on the World agent Select Click this to select or move a component on the Canvas New Space Click this to place a space on the World Canvas New Agent Click this to place an agent on the Canvas Agent Based Simulator User s Manual 2 3 New Variable Click this to place a variable on the Canvas You can also add the components you want to the toolbox Click the agent or variable on the canvas you want to import then go into the Settings menu choose Toolbox then select Add The component you selected is added to the toolbox Segregation ABS File Edit View Add Settings Run Playback Window Help bre fe amp hhitial Value Default Value 2 Output Simulation Mo
13. 2 In the disk1 folder run Setup exe Uninstalling 1 In Control Panel double click Add Remove Programs 2 At the Install Uninstall tab select Agent Based Simulator from the list of programs then click Uninstall 4 Basic Concepts Agent The dictionary defines agent as one who acts on behalf of another but here it is a construct that is substituted for an actual entity in a simulation and behaves as if it were that entity It exerts effects on itself and others according to certain rules In specific terms an agent performs actions such as referencing and changing the values of its variables creating new agents and deleting old ones To speak figuratively it can see items that other people are carrying variables and can give and receive such items but it doesn t know what other people are thinking rules World agent This is a special agent at the highest level and forms the frame of reference for this simulation Other components are defined within it producing the simulation model 0 2 Agent Based Simulator User s Manual Space This is a two dimensional space to which an agent or variable belongs Variable This is like a carton for string and numerical value text or other data that an agent has It corresponds to terms such as x and y in mathematics Computers cannot process vague definitions such as friendly or short tempered and so all aspects of an agent s personality are maintained
14. Select the variable you aal C Toggle want to manipulate Rangel tofa with the Control Panel Slide Bar hr Spacing jl Note that you can C Input select only variables immediately under World Interface Button Select this when you want to assign a value when the button is ON Interface Toggle Button Select this when you want to assign respective values when the button is ON and OFF 2 30 Agent Based Simulator User s Manual Interface Slider Select this when you want to intermittently vary a value within specified range by dragging a Slider to the left or right Interface Direct Entry Select this when you want to directly type a value to be assigned to the variable 2 3 Simulation Execution Features After making the Control Panel settings as require you can run pause and stop simulations perform stepped execution and change variables during simulation To execute a simulation use the Control Panel window Run button Click this to start a simulation Step button This executes a simulation one step at a time Each click of the button executes one step after which the simulation pauses Pause button Click this to pause a simulation Stop button Click this to quit a simulation When you push ESC key exit a simulation If you have specified variables to change in the Control Panel settings then several elements are added to the Control Panel window Button Used
15. right click the X variable to display the context menu Next from the context menu choose Initialize to return the values of 5 10 and 15 for the respective X variables to 0 In the tree click the Y variable to select it then from the menu bar go into the Settings menu and choose Set Default to return the setting to the default value of 0 1 4 2 Using World When there is a large number of agent for example 100 or 200 how can we assign initial values to them efficiently If they are arranged regularly then it should be enough simply to write a rule somewhere However in the rules for an agent although local information for the agent itself and its surroundings are determined this isn t practical for manipulating multiple agents as a group More accurately this is structurally unsound What we use at such times is World at the highest level World is also an agent so you can also write rules for it However what is special is that World rules are often used in cases of batch processing that affects all agents in the hierarchy gt World agent rules are often used to perform batch processing that affects agents in the hierarchy There is also common rules although we are not using them here To display the Common Rule Editor go into the View menu and select Common Rule Editor Because these rules can be referenced either from agents or from World it is sufficient to write a computational expression function used by both a
16. variable 1 and so on as map components In other words the corresponding number of elements must be arranged in the list You can select and edit existing map components by clicking Edit You can also select and delete existing map components by clicking Delete Agent Based Simulator User s Manual 2 21 Numerical Screen Output Settings This output method displays components as numerical values When you select this with Output Type to Add this dialog box appears Numeric Output Setting xj Output Screen Cancel Numeric Output Component List Tumber output 1 Add Edit Delete Numerical Screen Output Component List Add Clicking the Add button for Numerical Screen Output Component List displays this screen Component Name Setting Component of Numeric Output 4 x fn this field you can give Gonponenge1enent gk a the numerical screen output component a name of your Output eee choosing Output Value Enter the variable or Decimal computational expression you want to output Show Fractional Numbers This setting determines how many digits to the right of the decimal point are displayed If you want to display multiple components on the screen at the same time you need to add each of the components such as agent 1 agent 2 variable 1 and so on as numerical screen output components In other words the corresponding number of elements must be arranged in
17. which is relatively easy to learn For information about the required syntax see Chapter 3 Agent Rule Syntax Rule Editor Settings You can set the font for the Rule Editor by going into the Settings menu and selecting Other Settings Automatic Indent Other Setting When this check box is selected automatic oe a Rule Editor Setting indenting is performed for rules you write in the Rule Editor JV Indent Set Font ae Font Clicking Set Font displays the Font dialog box Leave output screen open al embed ModelFile Files Font Font style Regular Arial Black O Comic Sans MS Bold Courier Bold Italic O Courier New Fixedsys O Georgia x Effects Sample I Strikeout M Underline AaBbYyZz Color L Black Md Script This is an OpenType font This same font will be used on both your printer and your screen Agent Based Simulator User s Manual 2 9 Keep Output Screen After Running When you clear this check box the output screen is deleted when the simulation ends Import Model Description File Select File button You can embed a file describing the model in the job file The embedded file must be in HTML and images are not permitted You can view the embedded model description file at any time by going into the Help menu and selecting Model Description For more information see section 2 5 The Rule Editor view is immediately updated with the sett
18. 10 to 11 sites and the blue ants have a narrow field of view 2 to 3 sites and the red ants have large appetites 2 to 3 whereas the blue ants eat little 1 5 to 2 5 Also there are initial assets of 10 to 13 as acommon setting for both types of ants Segregation ABS File Edit View Add Settings Run Playback Window Help Dee stela Control Panel Simulating The sugar that serves as food is placed beforehand in islandlike mounds on the World map the closer to the center of each island the more sugar is available Each ant consumes its appetite s worth of sugar at every step so to get the most sugar possible each one looks around moves to the site with the most sugar then grabs every bit of sugar in the site which it hoards as its assets Because the sugar in the World would eventually run out under these conditions it is replenished a little at a time Each ant merely seeks and moves to the location where sugar is most plentiful but when seen overall it looks just like the ants are moving in a swarm over mountains of sugar If an ant s assets are depleted the ant dies Conversely if an ant stockpiles assets equal to at 1 4 Agent Based Simulator User s Manual least ten times its appetite it reproduces You can also change these settings however you like of course but first try running the simulation with the original settings 2 Settings Go into the Tutorial folder and open the Sugarscape abs file Th
19. 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 0 0 0000 0 0000 3 4 0000 0 0000 D 0 0000 0 0000 3 4 0000 0 0000 0 V RED ANT B Output selec men mE Individual Input select Target Agent Red Ant This indicates that current setting target is the initial value of the agent named Red Ant When you have selected a variable this field changes to Agent Variable Initialize variable name Enter the numerical values you want to set in the table under this Individually Set Agents When setting for multiple agents you can set the values individually for each by selecting the corresponding check boxes File Input File Output You can import the initial values from an existing file or save them in a file by clicking these buttons Agent Based Simulator User s Manual 2 15 2 2 2 Set Default Dialog Box To set the default values for vari ables Default Value Setting E xi by going into the Settings menu and Var Name ix choosing Defaults Ordinarily variables are assigned initial values but if a variable is added by an agent rule with _CreateAgent for example then the numerical value of this default is stored in the added variable 2 2 3 Output Settings Dialog Box The Output Item List dialog Output Item List xi box appears when you go MElanT map into the Settings menu and s MIRA NUMBER OF ANTS choose Output graph and file output methods go into Output
20. ABS two dimensional map_1 E oj x zi File Edit View Add Settings Run Playback Window Help 18 x D SW eel E woOODS Control Panel i xi gt l m m DENSITY WOODS 100 20 Simulating 7 The following describes the Forest fire model Tree agents are placed randomly on a map at a specified density Tree agents have three states unburned green burning red and burnt black A tree in the burning state becomes burnt state in the subsequent step If a tree is in the burning state any unburned trees in the eight adjacent locations become burning state In the first step trees on the left edge are burning A 18 Agent Based Simulator User s Manual A 3 1 Creating a Simple Model But Something Is a Little Strange The rules for the Forest fire model are truly simple In the first model we start by creating the two dimensional space and the tree agents then make the settings for the World variable and the Control Panel window to allow us to vary the tree density Then we write the rules for World and the tree agents Creating a New Setting File From the File menu select New Adding the Space Create a single new space component under the World hierarchy then make the settings for the properties Name the space component Two dimensional Space Set a size for the grid model of 50 each for both X and Y and set it not to loop Adding the Variab
21. Assigning initial values to variables individually Initialize Assigning initial values to variables in a batch Set Default Debugging 1 3 14 Let s Review Have you mastered the basic structural elements in the ABS programming environment Do you understand the flow of the basic steps for creating an ABS program Component locations and settings Output settings Describing agent rules Running and debugging Did you try making Agent Based Simulator settings yourself while referring to the text Did the programs run as expected Agent Based Simulator User s Manual 1 21 1 4 Making Modifications for a Slightly More Complex Model In this section you ll add increasingly complex elements while modifying the rule for the turtle that moves back and forth The programming concepts covered include declaration of variables loop control random numbers functions and arrays So far the examples we ve seen have been somewhat mechanical but incorporating random numbers in the rules makes it possible to make agents move separately This makes the examples more like actual agent models This section also contains numerous techniques and tricks for using Agent Based Simulator so be sure not to overlook them 1 4 1 Resetting the X and Y Variables to Their Original State In Prog05 abs we set the initial values and default values for the X and Y variables so let s return these to their initial state In the tree
22. Consider for a moment how we should express this 1 16 Agent Based Simulator User s Manual rule It should be able to change direction when it reaches the edge of the screen but the orientation cannot be determined from just the agent s X and Y coordinates In this example we are not using DIRECTION which controls the orientation We ll add a new variable to the turtle agent that indicates the direction of advancing along the X axis as a positive or negative value In the component tree right click the Turtle agent to display the context menu From the menu select Add Variable The Variable Properties dialog box appears Enter DIRX for Variable Name and Integer for Variable Type Leave Number of Dimensions set to 0 Then click OK 2 Adding a Conditional Branch Rule Before we write the code let s write out the rule in text form e Initial rule Assign 1 to DIRX e Execution rules If the X coordinate is 0 or less than 0 then assign 1 to DIRX changing the orientation to the front e If the X coordinate is 49 or greater than 49 then assign 1 to DIRX changing the orientation to the back e Add the value of DIRX to the X coordinate When we write the code for this it looks like the following Prog03 abs Turtle agent rule Agt_Init my DIRX 1 Agt Step If my X lt 0 Then my DIRX 1 EndIf Ifmy X gt 49 Then my DIRX 1 EndIf my X my X my DIRX To review what you learned earlier Agt_Init is a rule that
23. Describing agent rules 4 Running and debugging You re now finished making the settings for a simple agent but clicking the Run button in the Control Panel window still will not display anything Click the Stop button to go back to the original state To display something while running you need to add output settings gt Output settings are required to run a simulation From the menu bar select the Settings menu and choose Output The types of output items include Time series Graph Bar Graph 2D Map Numerical Output and File Output From the drop down combo box choose 2D Map then click Add The Two dimensional Map Settings dialog box appears Leave Map Name unchanged as 2Dmap_1 and Map Title unchanged as space and in the Map Component List click Add The Two dimensional Map Component Space Property x Settings dialog box appears Change Component Name to turtle leave Space Name everything else unchanged then click OK Space Type two dementional to close the dialog box This adds turtle to the Map Component List Dimention 2 x so In the Two dimensional Map Settings dialog box click OK to close the dialog eS EE E 3 tput It box When you go back to the Output Item so List you see that 2Dmap_1 has been Treating Edge added Not Loop C Loop Mer meni Agent Based Simulator User s Manual 1 13 Untitled ABS File Edit View Add Settings Run Pla
24. Punctions derrien E i E Bian eee ae 3 14 375 Collection FUNCHONS areeiro ot aeeiiaii ieee e ee ao eea e ladder ssiestayes 3 14 3 6 Space Functions s nninanon na a ea E a a ein 3 15 3 7 7 File Input Output Functions 20 0 eee ceseceeceseceseecscececeseceseeeaeesaecaeceseeeeeseaeenaees 3 15 30 8 Other PunctOns hissiin angr eshte VEE KEE SE ae aaan 3 15 3 8 Reserved Words s erssian soinnin o e EA EEA 3 15 39 COMMENTI teien Ei a e E E neha E E A T 3 17 310 Error Correction areeiro aE E A EAE E ae 3 18 Creating More Advanced Models A 1 A Model Using Internal Functions Simple Segregation Model A 2 A 1 1 Preparing the Simulation Components 1 0 0 0 cc eseesceeceseceneeeeeeeeceseeseceseeeeneeaaes A 2 A12 Wilting the Rulesissa iei a e ee elu te de A 6 A 2 Making It Easier to Use Segregation model Using the Control Panel Window A 8 A 2 1 Making It Possible to Change the Threshold Value 00 0 0 cee eeeeeeeeeseeeseeereeenees A 8 A 2 2 Making It Possible to Change the Starting Number of Turtles 0 ee A 10 A 2 3 Quitting the Simulation When the Turtles Stop Moving 0 0 0 eeeeeeeesseeeeeeeee A 12 A 2 4 Adding a Time series Graph and Step View 0 0 ci ceecsseceseceseceneceseeeseeeeeeeees A 14 A 3 A Fairly Complex Model Using Collections Forest fire Model A 18 A 3 1 Creating a Simple Model But Something Is a Little Strange oo A 19 A 3 2 Synchronizing the States Using a Backup 0 ee ee
25. To escape from a For loop Fori 0 To 10 Step 1 Forj 0 To 10 Step 1 If conditional expression for escape Then Break EndIf eee Escape one level Nextj Nexti 3 6 8 Other Statements Return statement When function execution ends this statement returns control of execution to the location where called from The function with a return value can return a value at this time The format is as follows Return expression Important There is not limit on the number of Return statements that can appear within a function Important The following cases result in a compile error e When the function is defined as returning a value and an expression is omitted e When the function is defined as returning a value and the data type of the return value differs from the data type of the expression e When the function is defined as not returning a value and an expression appears 3 7 Internal Functions Agent based simulator has predefined functions called internal functions These functions can all be called from within functions The internal functions are listed below 3 12 Agent Based Simulator User s Manual 3 7 1 Numerical calculation Functions name 2 Calculates the arctangent trigonometric function 3 3 i integer less than or equal to the real number 6 7 8 9 10 i 3 7 2 String manipulation Functions Function nam 3 7 3 Data manipulation Functions Action Conver
26. and subsequent characters must be a letter numeral or under score e A name must be 100 characters or fewer e Reserved words see section 3 8 cannot be used as names Important Letters are not case sensitive 3 4 Agent Based Simulator User s Manual For examples Sum sum_x and sum100 are correct names SUM Sum and sum are all considered to be identical The following names are incorrect e Ix A numeral cannot be used as the first character e x A special symbol cannot be used e next Reserved words cannot be used 3 5 Variable Declaration Block This is a section that declares variables to be used only within the relevant function Variables must be declared before they are used If a variable is used without defining it first an undefined error occurs during compiling Variables declared here are called local variables They can be referenced or changed only within the function where they are declared Local variables are initialized when execution of the function starts and are destroyed when execution of the function ends When initialized variables of String data type are reset to a null string and other variables are reset to O zero 3 5 1 Declaration of Variables The format is as follows This may be omitted if local variables are not used Dim variable name I As variable type variable name n As variable type Examples Dim x As Integer Dimx1 As Double x2 10 As Double
27. in an error and cause the simulation to stop gt If condition Then rule when condition is satisfied Else rule when condition is not satisfied End If Now that you ve completed the rules for red turtles try using them as the basis for writing the rules for the blue turtles The answer is as follows Agent Based Simulator User s Manual A 7 Seg01 abs Blue turtle agent rule Agt_Init Agt_Step Dim redTurtleNumber as integer blueTurtleNumber as integer turtleTotal as double redTurtleNumber _ViewCountAgent my X my Y 1 World twoDimensionalSpace redTurtle blueTurtleNumber _ViewCountAgent my X my Y 1 World twoDimensionalSpace blueTurtle 1 turtleTotal redTurtleNumber blueTurtleNumber If blueTurtleNumber gt 0 Then my happiness blueTurtleNumber turtleTotal Else my happiness 0 EndIf if my happiness lt 0 6 Then _MoveToSpace my X my Y 3 endif A 2 Making It Easier to Use Segregation model Using the Control Panel Window When you try running the simple segregation model covered earlier you see that it shows exactly the same operation as the segregation model included in the tutorial With the simple model however you can t change user parameters unless you start the Rule Editor Accordingly as the next step we ll try using the Control Panel window and the World variable to improve it to a user friendly segregation model Here we ll add the following features e Ability to change the thr
28. is employed for simulations of strategy and the like The setting for Edge of Space determines whether coordinates wrap around to the opposite side when they exceed the boundaries of the space When set to Loop an agent that disappears from the right side appears again on the left side like with a LOGO graphic turtle Note that because this feature is effective only in the functions of Agent Based Simulator processing code must be implemented in the program Agent Agent Based Simulator User s Manual 1 11 A component that acts and interacts in a simulation according to certain rules is called an agent An agent acts on and is affected by other components Agent Based Simulator makes it simple to place multiple agents and carry out simulations Variable This is something like a container for storing the information and state of a component in the form of numerical values or text It may be useful to consider it more or less synonymous with variables in mathematics such as x and y What is unique about computer variables is that they are always typed Before you use a variable you must declare what type it is Types include Integer Double and Text data types It s necessary to use variables of the appropriate types matched to the kind of information 1 3 2 Adding a Component Space 1 Component placement and settings 2 Output settings 3 Describing agent rules 4 Running and debugging In the component
29. is executed only once when an agent is created The new variable is given a value of 0 in its initial state so unless the initial rule assigns a value 1 or 1 to DIRX the turtle won t move Something newly added here is a conditional branch rule This is written with this syntax If condition Then rule carried out if the condition is fulfilled End If The portion from Then to End If may be any number of lines It is usual to use tabs to indent this portion so that the branched structure of the conditional expression is apparent Also rule statements are not case sensitive upper case and lower case are not differentiated This means that my X and My X are actually processed in the same way gt If condition Then rule carried out if the condition is fulfilled End If gt Rule statements are not case sensitive Agent Based Simulator User s Manual 1 17 3 Running It A Turtle That Moves Back and Forth When you finish writing the rule go to the Control Panel window and click Run If it runs correctly the turtle continues moving back and forth changing direction at the edges of the map As an exercise to apply this try adding DIRY to indicate the direction of the Y coordinate as well creating an agent that moves diagonally The agent rule of the answer may look like the following Prog04 abs Turtle agent rule Agt_Init my DIRX 1 my DIRY 1 Agt_Step Ifmy X lt 0 Then my DIRX 1 EndIf Ifmy X gt 49 Then
30. it displays a warning message indicating the line where the problem occurred In almost all cases the error is caused by a mistake in how the line is written so check the points like the following e Spelling mistakes in variable and function names e Missing spaces around commands variables and operators Tip The spaces between words in the program list have an important meaning If the words are connected then may not be recognized correctly Remedy2 Include the DebugStrd function in the rules to verify the values of variables For example DebugStr World NumberOfTurles The value of the World NumberOfTurtles variable appears on the Debug Screen 2 Incorrect Output Settings With Agent Based Simulator nothing is displayed during execution unless output settings are made Also if only one type is displayed even though two types are supposed to appear or if the behavior of graphs or numerical values is different from what it expected it often means that there is a mistake in the output settings Often no warning is displayed for such errors so it can be difficult at first to discover where the problem is Remedy Output settings are essential for obtaining any kind of result during execution Check the output settings to make sure the Item Name and Component Name settings for the elements are correct If there are not enough output elements in almost cases a Component Name setting is incorrect 3 Inc
31. my DIRX 1 EndIf my X my X my DIRX Ifmy Y lt 0Then my DIRY 1 EndIf Ifmy Y gt 49 Then my DIRY 1 EndIf my Y my Y my DIRY 1 3 10 Adding More Turtle Agents 1 Creating Multiple Agents Now that you ve made an agent that moves diagonally let s try creating multiple agents However no matter how large we increase the number if we place all the agents at the same location at the start they will all move the same way That isn t very interesting so let s try changing where each one is placed at the start In the component tree right click the Turtle agent to display the context menu From the menu select Properties The Agent Properties dialog box appears Here set Number of Agents to 3 then click OK gt Use Agent Properties to make the setting for the number of agents 1 18 Agent Based Simulator User s Manual 2 How to Place Individual Agents at Different Initial Locations We want to start each agent at a different location To do this we need to assign different initial values to the X and Y variables that indicate the space positions of the agents How do we do this There is a feature that lets you assign individual initial values to variables In the component tree right click the X variable for the Turtle agent to display the context menu From the menu select Initialize The Initialize dialog box appears There are three Turtle agents numbers 0 1 and 2 Assign these values of 5 10 and 15 respectiv
32. range of 1 for a space in the grid model the target for calculation is 9 cells including the agent s own location Incidentally 1 is subtracted from redTurtleNumber because the agent NNN WY WN NO Fe FS e N Ne O KF N N e e e e N N NY NY NY LY itself is counted in the function s return value If you don t specify an agent name you can a count of Relation between own location and all neighboring agents by using All step ranges grid model gt Get the number of neighboring agents _ViewCountAgent X Y range agent name The second function is _MoveToSpace which moves an agent to a neighboring unoccupied cell Its usage is _MoveToSpace X Y movement range This effects movement if there is an unoccupied in the movement range centered at X Y If there is no unoccupied cell it returns the value True The preceding rule specifies movement to an unoccupied cell within three steps of the agent s own location gt Move to a neighboring unoccupied cell _MoveToSpace X Y movement range The If statement in the third block has another new element Else Processing to be performed in cases when the first condition doesn t apply are written between Else and EndIf You may be wondering why the If statement branches to this Else portion We do this because if there are no neighboring red turtles the value of redTurtle is zero and attempting to divide redTurtleNumber by turtleTotal would result
33. the Add button for Map Component List displays another dialog box for setting Component Name Setting Component of Two Dimensinal Map a x In this field you can Comp le lement_1 give this graph com ponent a name of Target RED_ANT Cancel your choosing Marker None Output Target Selec Select the components agents C Filenam and the like whose rial amare movement you want to view on the map Agent Fixed select Color Marker by Var This selects how ue Indicate markers are Informatio displayed for components on the map When you select None markers are not displayed When you choose Select you can select out of circle triangle square or x When you select File Name you can replace the marker with an image of your choosing by entering the path to an image file at present only icon files are supported When you choose Variable Name Specifying File you can select a variable in World Agent Color You select either Fixed Color which specifies a single color of your choosing or Variable dependent which makes the color change dynamically according to the value of the variable Agent Variable Information When you select the check box for Show Information the values of specified variables appear above the agents on the map If you want to display multiple components on the screen at the same time you need to add each of their components such as agent 1 agent 2
34. the data the variable handles These types include Integer data type Double data type and String data type but there are times when you want a value of a different type from the original one The foregoing case where you want to get a floating point number by dividing two integers is a typical example At such times you use type conversion functions CdblQ converts to Double data type CintQ to Integer data type Cstr to String data type and Cbool to Boolean data type True or False A 3 4 Changing the Pattern of How the Forest Fire Spreads In the Forest fire model the fire starts spreading all at once from the left edge Now let s add different kinds of variations to this 1 Rules for Starting the Spread of Fire from One Location at the Center of the Map A wildfire usually starts at one location so this makes the fire start to spread from the center of the map You need to change the initial rules for World and the tree agents Fire04 abs World rule Agt_Init Dim LimX as Integer LimY as Integer Dimi as Integer Maxi as Integer Dim Col as Collection Obj as Object LimX _GetWidthSpace World twoDimensionalSpace LimY _GetHeightSpace World twoDimensionalSpace Maxi Int LimX LimY World treeDensity 0 01 Fori 1 to Maxi _CreateA gent World twoDimensionalSpace tree Nexti _RandomPutA gent World twoDimensionalSpace tree False Col _CollectAround nt LimX 2 int Lim Y 2 0 World twoDimensionalSpace All if
35. view The procedure is as follows space Type two dementional 1 From the list choose Number of Turtles then click Edit This displays the Time Series Dimention 2 x 35 Graph Settings dialog box Size of 2 In th h List H n the Graph Component List select Happy Bs Turtles then click Edit Treating Edge 3 Change the Line Width setting from Ipt to C Not Loop 3pt select the Show Markers check box Loop then click OK You can make the settings in the same way for Unhappy Turtles as well Mer Now you re ready again Try clicking the Run button on the Control Panel men 1 2 2 Sugarscape Model A Simulation of an Anthill Making the Component Settings Again Making the Control Panel Settings You ve already seen how you can use the buttons in the Control Panel window to change the settings for simulations in real time Now let s try changing Number of Red Ants z Close a 1 From the Settings menu Output Item List select Control Panel Settings ME Basz ME INFORMATION 2 From the list choose MEAP InEss Number of Red Ants then v click Edit A User Settings dialog box appears z 3 Change the range of 50 Edit Delete to 200 50 to 500 iad s Add to Output Items As change Scale Interval to f time series graph 50 then click OK Agent Based Simulator User s Manual 1 7 Time Series Graph Setting HAPPINESS Vv
36. 0 8 when positive Object data type Object Agent entity value Collection data type Collection Array of variables of Object data type Basically you should choose String data type for text Integer data type for integers and Double data type for numbers that include a fractional portion Boolean data type is a little special it has a value of either Yes True or No False Object data type is used when you want to employ an object itself in an argument for a function Collection data type is used for a set of such objects Number of Dimensions A variable is like a container for holding data In principle a single variable can hold only one item of data When a variable is newly created it has zero dimensions that is it s a point on a plane therefore it stores a single data item However that s not convenient for handling large amounts of data of the same type so by increasing the number of dimensions you can also increase the number of data items that can be stored Incidentally in the case of a single dimension variable the variable can store n 1 items of data counting from zero to the array size n In the case of two dimensions when the array size is m for first dimension and n for second dimension the variable can store m 1 x n 1 items of data This is indicated as variable m n The array size starts at zero so be careful to add one to the quantity Note You can any text you want up to a length of 256
37. 12 creating new 2 10 declaration 3 5 declaration block 3 5 initial value setting 2 14 local 0 3 new 2 4 name 3 5 properties 2 12 type 3 6 type declaration 3 4 Version information 2 40 _ViewCountA gent A 7 VisualBasic and ABS difference in notation 1 29 World agent 0 2 1 10 Index amp Information 3 For more information Kozo Keikaku Engineering Inc Innovative Information Technology Dept Phone 81 3 5342 1125 Fax 81 3 5342 1225 http www2 kke co jp abs e mail abs kke co jp 4 Index amp Information
38. Agent Based Simulator User s Manual 9 2000 Kozo Keikaku Engineering Inc Innovative Information Technology Dept Contents Introduction 1 What Is an Agent Based Simulator 000 eeeeeeesceceeeneecesnneeceeaaeceenaaeeeeaes 0 2 Ze Operating Environment menei eE R nes ato E AAE A 0 2 3 Installing and Uninstalling seeeeeeeeeenseeeesseeeeseeessseesseeesssreessersseresseseesseess 0 2 A Basic Concepts recor aa e E E EE E E EEEE 0 2 5 How This Manual Is Organized soensseeeeseeeeseeessseesseessseeessersseressrreesseese 0 3 6 Typographical Conventions Used in This Manual cesseceesseeeeeeeeees 0 4 An Introduction to Agent Based Simulator 1 1 Running the Samples ci negescb ce donticsesssicaveatevauesurpdasdtecesacteautcseesauseeternegeaeess 1 2 LEI Segregation Model s cs 22685 schts tel wate aI A eect en antic 1 2 11 2 5Sugarscape Model i nioniin n eni cncien Muli ede Wanita eit ae 1 4 Waki Manes ia apa seeen aaae aE EEEE A ESEETO EErEE ES ORSR 1 6 1 2 1 Segregation Model A Simulation of Segregated Living Among Turtles 1 6 1 2 2 Sugarscape Model A Simulation of an Anthill seseeeeeeeeeeseeesreeeesrrrrsreeseesssn 1 7 1 3 Constructing a Simple Model sssnseeeseeesesessersseesssesseesssesseeesseeseeesseeseee 1 8 1 3 1 The ABS Programming Environment eesseeeeesseseessesresrsrrssrerresesrerreeseerrsrresee 1 10 1 3 2 Adding a Component Space o cee ee
39. B backup variable for each agent object is assigned to state variable A 24 Agent Based Simulator User s Manual Changing the Tree Agent Rules Add the rules for backup variables to the tree agent rules What you need to do is to change the portions that write to the state variable to write to the state_B variable Fire02 abs Tree agent rule Agt_Init my state Color_Green my state_B Color_Green if My X 0 then my state_B Color_Red EndIf Agt Step Dim neighbors as Collection Dim neighboringTree as Object Dim Stp as Integer If My state Color_Red then neighbors _CollectAround My X My Y 1 World twoDimensionalSpace World twoDimensionalSpace tree For Each neighboringTree In neighbors If neighboringTree state Color_Green then neighboringTree state_B Color_Red EndIf Next neighboringTree My state_B Color_Black EndIf Agent Based Simulator User s Manual A 25 How does the simulation work now The backup should function correctly and you should no longer see operation where fire suddenly spreads to several sites in one step forest e ABS two dimensional map_1 E Oj x 18 x D ow bed EIE E wOODS Control Panel x Sion DENSITY WOODS 20 100 Simulating Mh A 3 3 Adding Display of Required Numerical Values to Simulation Execution Now that we ve eliminated some quirks in behavior let s try adding a screen to show the parameters
40. Graph Component Settings dialog box appears set Component Name to Moving Turtles Because Nonmoving Turtles can be determined by subtracting the moving turtles from the number of agents created in the Output Value box enter World numberOfTurtles x 2 World happyTurtles When you ve finished making the settings click OK to close the dialog box In the Time series Graph Component Settings dialog box click OK to close the dialog box Agent Based Simulator User s Manual A 15 Adding Numerical Screen Output to the Output View Select Numerical Output as the type of output to add to the Output Item List dialog box then click Add When the Numerical Screen Output Settings dialog box appears set Output Name to Numerical Output and enter Parameters as the window title Adding the Step Number to Numerical Screen Output In the Numerical Screen Output Settings dialog box go to Numerical Screen Output Component List and click Add Setting Component of Numeric Output Component STEP _GetCountstep i Output Decimal 0 When the Numerical Screen Output Component Settings dialog box appear for Component Name enter Number of Steps For Output Value specify _GetCountStep to display the step number When you ve finished making the settings click OK to close the dialog box In the Numerical Screen Output Settings dialog box click OK to close the dialog box Output Item List E xj ens z Aa ME I
41. NFORMATION MER HAPPINESS Add Edit Delete Add to Output Items As time series graph Does the screen look like what you see above Now let s try running it Execution result is A 16 Agent Based Simulator User s Manual Segregation ABS File Edit View Add Settings Run Playback Window Help OSH ea Simulating a y Agent Based Simulator User s Manual A 17 A 3 A Fairly Complex Model Using Collections Forest fire Model KR amp NN We constructed the previous model using internal functions in Agent Based Simulator such as _ViewCountAgent and _MoveToSpace In some cases however internal functions may not be enough to do the job At such times Collection data type variables and functions can demonstrate impressive power Briefly put a collection is an aggregate of objects agents It is used when you want to obtain a set of specific agents or conditions surrounding specific coordinates Collections are manipulated like array variables However their notation is slightly idiosyncratic so examine the example programs closely The example covered here is the Forest fire model which is based on the Forest Fire pro gram for StarLogo It simulates whether a fire that starts burning at the left edge of a map will spread from tree to tree to reach the right edge of the map The probability of reaching the right edge differs greatly depending on the density of the trees forest e
42. RandomPutAgent but in this case the important thing is the random placement feature and the return value is not needed In cases where the return value is not used the assignment statement is frequently omitted as in the following rule gt RandomPutAgent places agents randomly Prog07 abs World agent Agt_Init _RandomPutA gent World space turtle False 1 5 2 Adding Random Factors to Variable Values The RndQ function is used to assign random values to variables RndQ generates a random number greater than or equal to 0 and less than 1 In many cases however a random integer is required This can be obtained by using RndQ in combination with Int0 to truncate the portion to the right of the decimal point as in the following example i Int RndQ 5 In this case the variable i is assigned an integer value of from 0 to 4 If you want a value from 1 to a you can use i Int Rnd a 1 _RandomPutAgent which we saw can be replaced as following code Prog08 abs World agent Agt_Init Dim ias integer For i 0 to _CountAgent World space turtle 1 World space turtle X i Int Rnd Q 50 World space turtle Y G Int RndQ 50 Nexti Now let s also try making the direction random The variables DIRX and DIRY must be added to the agent in advance Also let s remove the remaining initial rule for the Turtle agent You ll notice that the complicated expression 1 Int Rnd 2 2 appears in this program This i
43. _CountCollection Col gt 0 then Obj _GetObject Col 0 Obj state_B Color_Red else World twoDimensionalSpace tree X 0 int LimX 2 World twoDimensionalSpace tree Y 0 int Lim Y 2 World twoDimensionalSpace tree state_B 0 Color_Red end if Agent Based Simulator User s Manual A 29 Fire04 abs Tree agent rule Agt_Init if my state_B lt gt Color_Red then my state Color_Green my state_B Color_Green endif In the World initial rule the first section is almost the same as before but the second half is very different In broad terms the rule means this If there is a tree at the center of the map it is burning If there is no tree then move the first tree agent having an ID of 0 to the center of the map and make it burning For the tree agents the trees other than the one that is burning must be initialized to unburned green so we change the conditional statement to take trees that haven t prior been assigned Color_Red and make them unburned Color_Green forest e ABS a Ioj x File Edit View Add Settings Run Playback Window Help TEE two dimensional m ap Number output 0 x LOST WOODS 627 RATE LOST WOODS 33 9 Control Panel gt o u m DENSITY WOODS 20 100 Simulating er a ea 2 Changing the number of Neighborhoods In cases where wind direction exerts an effect fire does not readily spread in the upwind direction Here we make the sett
44. ack Run Simulation button When you pause at a step and click this button you can then set the values in that step to their initial values and execute the simulation again If you want to save a new log file when you execute the simulation again you need to redo the settings in the Log File Settings dialog box 2 32 Agent Based Simulator User s Manual Playback List Panel The step numbers together with the date and time of simulation execution are listed in ascending order on the time axis When you pause at a step and click the location you want on this list you can display the step s actual output You can also display their images by using the arrow keys instead of clicking Agent Based Simulator User s Manual 2 33 2 5 Analytic File Output Feature To use this feature you must first make settings run a simulation and generated a log file When you open the log file you can get analitic file When you do this the Analytic file menu becomes available for selection Selecting Analytic file in this state displays the Analytic file output dialog 1 6 and sets output formats Enter Output Simulations Output Simulation Setting All Simulatior C Random Se Count C Every N Simulatior N C Specified Simula Output Simulation Setting When a logfile contains multiple simulations sets simulations for output data 2 34 Agent Based Simulator User s Manual Output Step Set
45. ains a value of either 1 0 or 1 This makes the agents occasionally appear to stand still gt Df Int Rnd A 0 Then End if causes a branch with a probability of 1 A 1 6 Creating a Space That Wraps Around Space that is looped wraps around is a coordinate system used by LOGO graphic turtles and the like The top and bottom of the screen are connected and so are the left and right sides For example when an agent disappears off the right side of the screen it reappears on the left edge This coordinate system is useful when simulating a space like a ball However it takes a little extra work to handle it with Agent Based Simulator Let s take a look at the steps and rules that are involved 1 26 Agent Based Simulator User s Manual So far in Progxx abs we used If statements to make an agent change direction when it reached the edge of the map Now we ll make the space wrap around and eliminate the map edge processing code 1 6 1 Space Component Settings First in the ABS Space Properties dialog box there is an option for selecting either Loop or Do Not Loop To make the space wrap around you must first select the Loop option However because this is valid only for built in functions related to space selecting Loop is not enough to establish the conditions for actually looping gt The Loop setting in the Space Properties dialog box is not enough by itself 1 6 2 Creating a Function to Adjust the Coordinate P
46. already embedded in the job file see Rule Editor Settings you can view the embedded model description file by going into the Help menu and selecting Model Description Viewing the Help File Going into the Help menu and selecting Show Help displays the standard help file This is mainly a reference for agent rule syntax Use it together with this manual About Agent Based Simulator Going into the Help menu and selecting About displays the following window that provides information about the version of Agent Based Simulator About ABS Agent Based Simulator Version 1 1 Copyright C 2000 2 7 Debug Screen Feature Debug Screen Output You can output a debugging screen by including the _DebugStr function in rules _DebugStris an internal function to display debugging information Format _DebugStrargument If the argument is a text string it must be enclosed in quotation marks For example Agt_Init Dim X as Integer X 0 _DebugStr Initial value amp X X X 1 _DebugStr After adding 1 amp X 2 40 Agent Based Simulator User s Manual Execution Result DebueStr Initial value 0 pfer adding 1 1 Agent Based Simulator User s Manual 2 41 Chapter 3 Agent Rule Syntax This section is the specification for the language used in agent rules for the Agent Based Simulator The content may be somewhat advanced for persons with no programming experience Please study it a
47. alue Number of Executions with Different Initial Value This sets the number of times to execute the simulation with the initial value varied randomly Set Different Values for Same level Variables Select this check box when you want to apply the different random number to identical variables of the same agent for example turtle 0 turtle 1 turtle 2 2 28 Agent Based Simulator User s Manual Report Output Tab Report File Name Simulation Setting x This sets the name of the file aaah Log runtype multi Report for report file output Clicking Set displays a dialog Report File box for saving where you AAE O aD nace can specify a file name and location of the report file Other E Report Component List Delimiter You can choose any of four z types of separator charac al ters Tab Comma Space or Other x Report Component List a Edit Delete Use the Add button to add components you want to out put in the report file use the Edit button to edit compo nents and use the Delete button to delete components Clicking Add displays the Report Output Component Setting dialog box Component Name In this field you can give feport Output Component Setting E xj the report output Componentjelement_1 component a name of your choosing Output When done faneel Output C Step 0 This selects the timing for C Step Int F outputting the comp
48. ar Graph Output Settings This output method displays components as a bar graph When you select this with Output Type to Add the following dialog box appears Almost all the setting items are the same as for time series graphs Setting Bar Chart jar graph 1 Agent Based Simulator User s Manual 2 19 Two dimensional View Map Output Settings This output method arranges agents and variables on a two dimensional view map to show their movement increase and decrease When you select this with Output Type to Add the following dialog box appears Two Dimensinal Map Settings WORLD BASE xi Name two dimensional map 1 i BASE Title Cancel Exp Notes v Ruled Line f Background J gt Setting of X axis Setting of Y Axis Axis Axis Min Min 0 fo Max fas Max 49 ii Map Component List Add Edit Delete La a L gt Lb Show Gridlines When you select this check box horizontal and vertical gridlines are drawn on the two dimensional map Show Backgroud Graphics When you select this check box a backgroud graphics is displayed on two dimensional space X axis Settings Y axis Settings It s possible to display only specific portions on the map by making settings for the minimum and maximum values The initial maximum values are assigned the space size 2 20 Agent Based Simulator User s Manual Map Component List Add Clicking
49. ars leave Output Name set to Numerical Output_l and enter Parameters as the window title Agent Based Simulator User s Manual A 27 Adding the Step Number to Numerical Screen Output In the Numerical Screen Setting Component of Numeric Output Output Settings dialog box Component Step go to Numerical Screen Output Component List and Output _GetCountstep i click Add When the Numerical Screen Output Component Settings Decimal o 8 dialog box appear for Component Name enter Number of Steps For Output Value specify _GetCountStepQ to display the step number When you ve finished making the settings click OK to close the dialog box Adding Burnt Trees to the Numerical Screen Output In the Numerical Screen Setting Component of Numeric Output Output Settings dialog box Component LOST Woops go to Numerical Screen Output Component List and Output WORLD LOST_WOODS click Add Cancel When the Numerical Screen Output Component Settings Decimal o 4 dialog box appear for Component Name enter Burnt Trees For Output Value enter World burntTree When you ve finished making the settings click OK to close the dialog box Adding Burnt Rate to the Numerical Screen Output In the Numerical Screen Out Setting Component of Numeric Output put Settings dialog box go to Component RATE LOST WOODS Numerical Screen Output Component List and click o Cdbl utput A
50. art Value End Value Range of Change These set the start value end value and range of change for the variable to be changed Number of Executions with Same Initial Value This sets the number of times to execute the same simulation before changing the initial value When Initial Values Change Setting Is Set to Random Initial Value Change Variable Simulation Setting E xj Name Sin Log runtype multi Report When you want to perform a simulation with the initial Initial Value Change Setting value of a particular variable gone Pdacens changed randomly then enter the variable name here For instance if you want to ae execute a total of 10 types of simulations with random numbers in the range of 0 to Min fo Max f 1 used as the initial value of Repeat Number in Same 1 a particular variable P Repeat Number in f ordinarily you would have to redo the setting of the initial IV Set Different Number ir value ten times and run a simulation for each one By using this setting however you can make the setting once and perform simulations while varying the initial value automatically until the conditions are fulfilled Minimum Value Maximum Value These set the minimum and maximum values of the range of random numbers for the variable to be changed Number of Executions with Same Initial Value This sets the number of times to execute the same simulation before changing the initial v
51. as numerical and text data in these variables Local variable This refers to a variable used temporarily only within an agent rule Other agents do not have access to it Agent rule This is a rule that governs how an agent acts In a simulation an agent acts according to such rules The values of variables may change but agent rules remain unchanged unless modified by the user There are three kinds of agent rules initial rules Agt_Init which are executed once when an agent is created execution rules Agt_Step which are executed at each step through a simulation and user defined functions which are defined by the user Model This refers to the set of components that the user constructs The state when components have been placed rules have been formulated and settings for output and the like have been completed is called the model ABS file This is a file in which the data for a created model is saved It is made up of component information and information on simulation settings and if a log has been made it also includes the log data 5 How This Manual Is Organized This manual is made up of three chapters an appendix and an index The contents of each are as follows Chapter 1 An Introduction to Agent Based Simulator This chapter is arranged in two parts that take a staged approach to learning The introductory section describes how to perform actual simulations using two tutorial files and the main text gra
52. ation Components The segregation model is a classic model using a two dimensional space In a space using model you ordinarily prepare the simulation components in the sequence of space agents and agent variables Then to obtain screen output during execution you go into Output Settings and select Two dimensional Map A 2 Agent Based Simulator User s Manual Creating a New Setting File From the File menu select New Adding the Space Create a single new space component under the World hierarchy then make the settings for the properties Name the space component Two dimensional Space Select Grid Model set 35 each for both X and Y and set it to loop wrap around Adding the Agents Under the Two dimensional Space hierar chy create two new agents and make the settings for their properties Name the agents Red Turtle and Blue Turtle respectively Set the number of agents to 500 for each agent Space Property Space Name BASE space Type two dementional Dimention B Size of x 3s T 3s Treating Edge Loop mn Agent Property Agent Name RED_TURTLE soo Number Mer men Agent Based Simulator User s Manual A 3 Adding the Agent Variables Var Property Create one new variable each under the War Mean hierarchies for Red Turtle and Blue Turtle x t Name the variable Happiness Set the pa voci kt n variable ty
53. ause rules can easily become long processions of hard to understand text we recommend commenting your programs liberally to make them easier to understand when inspected later You can add comments at any place where a blank can be written The methods that can be used to write comments are given below Everything from the to the end of the line is a comment Example In this case sum 0 is interpreted as a rule sum 0 Initialize the total value Similar to 1 Example Determine direction of advance then move direction Rnd 360 here Everything from the to the is a comment This may span more than one line Example KEKEE K K K K K K K K K K K K K K K K K K KK K K K K KK K K K K KK K K K K K K K K K KK K Turtle rule k Examination of Schelling s segregation model FEKE EE E E KE E E E K K K E K KE 246 K K K K K K K K K K K K K KK K K K K KK K K K K KK K K Agent Based Simulator User s Manual 3 17 3 10 Error Correction When a rule with a incorrect syntax is written in the Rule Editor an error is displayed Typical error messages and their remedies are given here 1 A type name Boolean Integer Double String Agent Space Object or Collection is required after As Remedy Check the type declarations for the function s return value and variables 2 xx is undefined Remedy Do Xx and exist Also check to make sure there are no typing errors
54. cal disjunction expressions Xor 13 Logical exclusion Assignment a 14 Assignment assign result of expression variable name operator expression 3 6 4 Function Calls In terms of syntax a function call is a linear expression A function call may be used in an arithmetic relational or logical expression or may be used as an independent statement Note that a function with no return value can be used only as an independent statement Function name argument 1 argument 2 Argument The number of arguments and their types must match what has been defined Only variable names can be specified as arguments 3 6 5 Conditional Statements Conditional statements cause processing to branch according to certain conditions 1 When the expression evaluates to true the block is executed If expression Then Block statement EndIf Agent Based Simulator User s Manual 3 9 2 When the expression evaluates to true block 1 is executed When it evaluates to false block 2 is executed If expression Then Block statement 1 Else Block statement 2 EndIf 3 When the value of the expression is true the corresponding block is executed When all expressions evaluate to false block n is executed If expression 1 Then Block statement 1 Elself expression 2 Then Block statement 2 Elself expression 3 Then Block statement 3 Else Block statement EndIf 3 6 6 Loop Statements Loop statements perform repetiti
55. characters What you enter here has no effect on the simulation so you can use this area for making notes 2 12 Agent Based Simulator User s Manual 5 Click OK to close the dialog box A variable appear on the canvas Canvas AGENT Now you ve created the new variable VAR_1 under an agent You use the same procedure to create a new one immediately under the World agent or a space 2 2 Simulation Setting Feature 2 2 1 Initialize Dialog Box This is for setting the initial values for components To display the Initialize dialog box select the components in the Tree then go into the Settings menu and choose Initialize The screen for setting the initial values varies according to the type of component Initialize Dialog Box for Two dimensional Space Initial Value Target Space BASE Expand f LIMIT_FOOD x k Ime a Ee ES Bea feel Bee es Bes Ee Re Be BS Fd ese oe Eel B ed Gs BS GR S Gees Es es Be ed BS eS RE BS Se Ee Gs KBS Eel Ba ed ee Bee B Bees Marker Ese SSS Fee Ee ES RS RS Fs eed BS Ces Bs RA R Ges Se Se ERS Gs EES RE ES BA ES ele Bee Ba BA Gee ee Geel E eee Sd Gard BS Gees E GS FSS ee BS GS eB Ba BE __ ierec Perec ca Bs TEEL TEE See ee eee o ii 3 Ed eee oe B BH eee ESS Be Pope AEETI IIIT ee es ee ES AA a eee Eee EELLLI Input by Vv aji gt Indicate RED_ANT BLUE_ANT LIMNIT_FOOD gt OK Cancel Range 1l Input select
56. d _GetHeightSpace 1 7 Conclusion Here is what you ve learned in this section 1 28 Agent Based Simulator User s Manual 1 7 1 Terms and Techniques How to use World agent rule Dim statements Loop control For Next statement Function _CountAgent How to specify hierarchical components Agent ID Array variable _RandomPutAgent Obtaining random integers from 0 to a Branching with a probability of 1 A Spaces that wrap around loop User defined function Function _GetWidthSpace _GetHeightSpace 1 7 2 Let s Review Is it clear what processing is performed in the sample programs Try changing the ranges of the variables in the sample programs and consider other applications 1 7 3 Differences in Notation between Visual Basic and Agent Based Simulator The rule format in Agent Based Simulator is basically the same as in Microsoft Visual Basic but there are some difference These differences are shown below Item Agent Based Simulator Visual Basic meron daimia Function Function EndFunction Sub Sub EndSub Return return value Function name Return value Function return value pe er f X Specified as argument of Return function Input in function name Variable type declaration Required Variant data type when not specified Comparison operator If A B Then EndIf a A B Then EndIf Two
57. d display of numerical values to the output view see Seg04 abs file Adding a Time series Graph to the Output View From the menu bar select the Settings menu and choose Output When the Output Item List dialog box appears select Time series Graph as the output type to add then click Add When the Time Series Graph Settings dialog box appears set Name and Title to Turtle Graph and select the Show Legend check box A 14 Agent Based Simulator User s Manual Adding Graph Components Nonmoving Turtles to the Time series Graph In the Time series Graph View dialog box go to Graph Component List and click Add Setting Component of Time Series Graph LineWidth l pt LineColor Select Marker Indicate When the Time series Graph Component Settings dialog box appears set Component Name to Nonmoving Turtles In the Output Value box enter World happyTurtles When you ve finished making the settings click OK to close the dialog box gt In the Output Value field specify a variable that begins with World or enter a computational expression Adding Graph Components Moving Turtles to the Time series Graph In the Time series Graph View dialog box go to Graph Component List and click Add Setting Component of Time Series Graph WORLD N_ TURTLE 2 Cancel WORLD HAPPY_TURTLE LineWidth l pt LineColor select Marker Indicate When the Time series
58. data type Collection data type Space data type Logical conjunction Modulo Logical negation Logical disjunction Logical exclusion sed in Do While and Do Until statements sed in Do While statements sed in Do Until statements sed in Do While and Do Until statements sed in If statements sed in If statements sed in If statements sed in If statements sed in For statements sed in For statements sed in For statements sed in For statements sed in jump statements U U U U U U U Used in If statements U U U U U U U sed in Goto statements Identifier declarations and references Used in declarations sed in declarations sed in declarations sed in function definitions U U Used in declarations U U sed in function definitions The name of a function executed only once at the start of a simulation 3 16 Agent Based Simulator User s Manual Agt_Step The name of a function executed repeatedly in a simulation Up Indicates the agent one hierarchical level higher My Indicates the relevant agent World Indicates the World agent All Indicates all agents used in the _CollectAround function Others Static Reserved for future use X Indicates the spatial coordinate of an agent Y Indicates the spatial coordinate of an agent 3 9 Comments 1 2 3 You can write comments in agent rules Because Agent Based Simulator ignores text in comments you can write anything in comments Bec
59. dd PaE WORLD LOST_WOODS Cancel Count gent WORLD BASE WOODS inn Decimal 1 When the Numerical Screen Output Component Settings dialog box appear for Component Name enter Burnt Rate For Output Value specify Cdbl World burntTree _CountA gent World twoDimensionalSpace tree 100 Set Show Fractional Numbers to one digit When you ve finished making the settings click OK to close the dialog box In the Numerical Screen Output Settings dialog box click OK to close the dialog box The function CdblQ appears in Output Value for the burnt rate This converts the data type of the value within the parentheses to Double data type Why do we go to the trouble of converting A 28 Agent Based Simulator User s Manual to floating point numbers when World burntTree can hold only integers The reason is because the results of division are affected If you try eliminating Cdbl0 the calculation results are always zero Because of the way internal processing performed in Agent Based Simulator the result of an Integer data type operator Integer data type operation is always Integer data type so the portion to the right of the decimal point in the result of the division operation is truncated In order make the result a real number we must make one or the other of the numerical values the Double data type Type conversion Functions To use a variable in Agent Based Simulator you must declare the type of
60. del Control Panel ye l Perty Default Value y Select New Space D New Agent 3 New Var a al ae The item you added here keeps the same attributes initial values default values rules and the like as the original component a O D Select New Space New Agent New War HAPPINESS 2 4 Agent Based Simulator User s Manual 2 1 3 Creating a New Space You can create a two dimensional space for observing the movement of agents on a plane 1 Go to the toolbox and click the Space Space Property x button The button should appear to be depressed Space Name 2 Click inside the Canvas World window Space Type 3 The following Space Properties dialog box Dimention B appears Space Name aao G re so Enter the space name you want The Y so default is SPACE_1 Treating Edge Space Type Not Loop Choose the type of space Select either C Loop the grid model or the hexagon model Number of Space Dimensions Mer Because this is a space the setting is 2 indicating two dimensions mn site for one agent or variable The default size is 50 x 50 Space Size This sets the size of the space with one Edge of Space When you select the Loop check box a component that reaches the edge of the space appears again on the opposite side When you select Do Not Loop components bounce back Note You can any text you wa
61. dually builds on the knowledge acquired to create models Start with this chapter to actually use Agent Based Simulator and familiarize yourself with the flow of simulations Chapter 2 Reference This chapter is organized by function and describes all of the setting screens where the user can make various settings Use this chapter as a reference using the index and table of contents to locate the information you need Chapter 3 Agent Rule Syntax This chapter describes the syntax of the agent rules that define agents Use this chapter as a Agent Based Simulator User s Manual 0 3 reference using the index and table of contents to locate the information you need Appendix This is an advanced course in Agent Based Simulator that will take you beyond the introductory material in chapter 1 It deepens your understanding of Agent Based Simulator through a hands on approach that covers the segregation model the forest fire model and other topics Index This is an index to frequently used terms in Agent Based Simulator The format chapter number page number is used to indicate the locations where entries appear in the text 6 Typographical Conventions Used in This Manual The typography of this manual follows the conventions described below Usage of Italic type Italic type sometimes Bold italic type is used to explain step by step procedures Italic and normal type are used to differentiate between descriptions o
62. e row from CSV file _WriteFileCSV Write one row to CSV file _CloseFileCSV Close CSV file 3 7 8 Other Functions Number Function name 1 SpecifyLoop 2 cetCount step 3 _GetCountSimulationNumber 4 exitsimalation 5_ Lexitsimulationtisg 6 7 _DebugStr Displays a string on the Debug Screen _Shell Execute a runnable program 3 8 Reserved Words When you write an agent rule you cannot use reserved words for variable names user defined function names or the like The names of internal functions also cannot be used Reserved words are listed below Constants True Indicates a true value Boolean data type False Indicates a false value Boolean data type Color_Red Indicates the color red Color_Green Indicates the color green Color Blue Indicates the color blue Color_Yellow Indicates the color yellow Color_Cyan Indicates the color cyan Color_Mazenta Indicates the color magenta Color Black Indicates the color black Color_White Indicates the color white Agent Based Simulator User s Manual 3 15 Type names Void Boolean Double Integer String Agent Object Collection Space Operators And Mod Not Or Xor Execution control End For To Step Next Break Goto Dm As By Val Function Sub Agt_Init No valid data type used as the type for the return value of a function Boolean data type Real data type Integer data type String data type Agent data type Object
63. e that the window already has two items Agt Init and Agt_Step Agt_Init is an initial rule that is executed only once when an agent is created in a simulation Agt_ Step is an execution rule that is executed at every step when the simulation runs The braces indicate respectively the beginning and end of the rule The necessary statements are written inside the braces gt Agt Init is an initial rule executed only once when an agent is created gt Agt Step is an execution rule executed at every step when a simulation runs 1 3 7 Writing the First Rule Now let s try writing the first rule Prog02 abs Turtle agent rule Agt Step my X my X 1 When you entered my a window for variables such as X Y and DIRECTION appeared Here we ll use X so use the arrow keys to choose X then press Enter The my is a special notation that points to the agent itself Here my X indicates the X variable included within itself At first glance this rule may appear to be mathematically incorrect but remember that in a program it is used not as an equality statement but as an assignment statement That is it signifies that the information on the right side of the equal sign is to be assigned to the left side of the equal sign If my X has a value of 1 then after rule execution my X becomes 2 To make code more readable add spaces between variable names operators such as the equal sign and and other words gt
64. ease in the number of agents you have to go into the Tree and open Properties which is a bit troublesome Accordingly for the next modification let s try making it simple to set the starting number of turtles using the Control Panel window The use of the Control Panel window and the World variable are the same as we saw earlier but in order to create just the required number of agents you need to use a special agent function A 10 Agent Based Simulator User s Manual Creating the Variable Under the World Hierarchy Add a single new variable immediately Var Property under the World hierarchy Var Name N TURTLE Set Variable Name to Number of Turtles Variable Type to Integer and leave Number Var Type Integer of Dimensions set to 0 Number of fo E 0 th D Arraysize o Mer meni Changing the Agent Properties Because agents are created in the World initial rule in Agent Properties set the Number of Agents to 0 for both the red turtles and the blue turtles Rewriting the Rules To create the agents add the following statements to the World initial rule Seg02 abs World rule Agt_Init Dim ias integer for i 0 to World numberOfTurtles 1 _CreateA gent World twoDimensionalSpace blueTurtle _CreateA gent World twoDimensionalSpace redTurtle nexti _RandomPutA gent World twoDimensionalSpace blueTurtle false _RandomPutA gent World twoDimensionalSpace redTurtle false _CreateAge
65. ecimal point are displayed If you want to output multiple data items to the output file at the same time you need to add each of the components such as agent 1 agent 2 variable 1 and so on as file output components In other words the corresponding number of elements must be arranged in the list You can select and edit existing file output components by clicking Edit You can also select and delete existing file output components by clicking Delete 2 2 4 Execution Environment Settings Dialog Box Here is where you make various settings for running simulations From the Settings menu choose Execution Environment Settings The Execution Environment Settings dialog box appears This dialog box has five tabs Simulation Log File Run Sequence Run Continuously and Report Output You can move among these tabs to make the settings 2 24 Agent Based Simulator User s Manual Simulation Tab Maximum Number of Steps Simulation Setting eS x The number of steps Sin Log runtype multi Report specified by this value is executed unless you quit the pene ce ee simulation partway through Max Step Step Maximum Execution Time Max Run 5 Minute Steps are executed until the End of time specified by this value elapses unless you quit the simulation partway through Ending Conditional Expression Steps are executed until the conditional expression entered here is fulfilled unless you quit the si
66. ect Agent entity value Collection data type Collection Array of variables of Object data type Space data type Space Space name defined in Tree 3 6 Execution Block 1 79769313486232 x 10 4 94065645841247 x 107 An execution block is composed of a group of executable statements and sets forth the action of the agent Block means a series of zero or more executable statements Executable statements include dummy statements assignment statements conditional statements loop statements jump statements and the like 3 6 1 Dummy Statements Dummy statements perform no execution They are used to make programs more readable Example Ifx 1 Andy 1 Then Else Z 0 EndIf 3 6 Agent Based Simulator User s Manual The above example is equivalent to the following one Ifx lt gt 1 Ory lt 1 Then z 0 EndIf 3 6 2 Assignment Statements Assignment statements assign values to variables The format is as follows Variable name Expression Variable name This is either a variable declared in an agent rule or an agent variable established using the GUI graphical user interface The format is as follows 1 For a variable declared within the agent rule e For a simple variable zero dimensions Variable name Example X e For an array variable Variable name Expression indicating the element number of the first dimension expression indicating the element number of
67. eeseceseceseceseceseeeeeeeseeeeneeenes A 23 A 3 3 Adding Display of Required Numerical Values to Simulation Execution A 26 A 3 4 Changing the Pattern of How the Forest Fire Spreads ces eeecesseeeeseeeees A 29 Index and Infomation Introduction 1 What Is an Agent Based Simulator An active entity that pursues its own benefit based on its own plan of action and decision making mechanism associated with individual internal attributes is termed an agent and the term multi agent is used to refer to an aggregate of correlated agents As an example in a simulation of how stock prices are determined the persons who wish to buy and sell stocks are called agents In this case individual examination of the buyers and sellers agents does not reveal the whole picture This is because stock prices are determined according to supply and demand the mutual relationships between sellers and buyers by invisible mechanisms acting within the group that differ from the rules of the individual active entities agents In this way Agent Based Simulator ABS simulates systems complex systems in which the rules for the behavior of the elements that make up the system change dynamically according to the overall context 2 Operating Environment A personal computer running Windows 95 98 Windows NT 4 0 or Windows 2000 3 Installing and Uninstalling Installation and Setup 1 Run abs exe to create a folder called disk1
68. eesseesseeseceseceseceseeeseceseecsaecsaecaecsaecneeesneesaes 1 12 1 3 3 Adding a Component Agent oo eee eeeeeeseenseceseceseceseeeeeeeaeeeaeesaecsaeenseeeeeeeaes 1 12 1 3 4 Adding Output Settings 00 ce ei ia hae aie Siete A R Te sets 1 12 1 3 5 Running It A Turtle that Does Nothing eee eeceeeeseeeseecnsecneeeeeeeseeeeneeeaes 1 14 1 3 6 Opening the Rule Editor cs c050 eeche ee ccectideviel eecteltebevl EE E a as 1 15 1 3 7 Writing the First RUE henson en aiae cht ae eeaeee aeaaaee 1 15 1 3 8 Running It A Bullet Turtle that Disappears from the Map s 1 16 1 3 9 Making an Agent that Moves Back and Forth Over the Map e 1 16 1 3 10 Adding More Turtle Agents 0 eee eesecssecseceseceseeeseesseceseeeeeseeeeaaecaeesseeeeeeaees 1 18 1 3 11 Ifthe Simulations Doesn t Run Correctly oo ee eeeeeeecencecnsecesecnseceeeeeeeeaes 1 19 13 126 Conclusion scsi Shel seta Siena a ees Dee eee steele 1 21 13 13 Terns and Techniques erioet e i e veg ii ace ans 1 21 1 33 14 ets Review sissciisies catenin olan eee etn ae eae aed sae eee hs 1 21 1 4 Making Modifications for a Slightly More Complex Model 1 22 1 4 1 Resetting the X and Y Variables to Their Original State 00 eeeeeeeeee 1 22 14 2 Using World niies a e Rei iii Gh tie even este E 1 22 1 4 3 For Variables Used Only in Rules First Define the Type eese 1 23 14 4 Loop Control isn nate an ra e etn ae ad Aenean 1 23 1 4 5 Determining the Number of Created A
69. el of experience you may safely skim through this section User Setting Component x Target N_RED_ANT Caneel Interface C Button Toggle Range 50 0200 Spacing fio Slide Bar Input 1 3 1 The ABS Programming Environment First start Agent Based Simulator Next on the menu bar choose File then select New A screen like the one below appears The area on the left side is called the Tree window The area next to the Tree is the World Agent Canvas On the right side of the screen is the Control Panel window Tree In Agent Based Simulator the various elements used in simulations are collectively called components The component tree on the left side shows this hierarchical structure as a tree diagram with the World agent always at the highest level Arranged beneath the World hierarchy are the space agent and variable elements Use is the same as for Windows Explorer Click the or symbol to the left of each element to display or hide the hierarchy under each Canvas The World space and agent components can include other components within themselves that is in their lower their hierarchies The Canvas indicates this hierarchical relationship using icons so it is synchronized with the Tree on the left side Double clicking on a component in the Canvas displays the included elements on the Canvas Clicking the World Canvas window displays the New Space New Agent and N
70. ely If the numerical values are obscured drag the right edge of the X item name to adjust the horizontal width When you have finished making the settings click OK to close the window Now when you run it you see interesting movement even with these simple rules gt Individual initial values are assigned to agents with Initialize 3 How to Assign a Nonzero Value to Agent Variables in a Batch Now let s say we want the Y coordinates for all the agents to start at 5 What should we do in this case There are two possible answers One way is to add my Y 5 to Agt_Init for the Turtle agents as we described in the section on the DIRX setting Another method is to use Set Default This is different from Initialize which we saw earlier instead it is a feature for assigning initial values to variables in a batch In the component tree click the Y variable to select it Then from the menu bar go into the Settings menu and choose Set Default The default value should be set to 5 Prog05 abs gt Set Default assigns initial values to agents in a batch 1 3 11 If the Simulations Doesn t Run Correctly 1 Component placement and settings 2 Output settings 3 Describing agent rules 4 Running and debugging The process of identifying the causes of program errors and correcting them so that the program runs properly is called debugging No matter how much care and planning you put into crafting a program
71. en you set the number of steps here a portion of the graph corresponding to the set number of steps is always displayed That is older data sequentially disappears from the left side Agent Based Simulator User s Manual 2 17 Graph Component List Clicking Add displays another dialog box for setting Component Name Setting Component of Time Series Graph 3 x In this field you can give Comp Jelement_ 1 this graph component a name of your choosing Output Cancel Output Value Enter the names of the graph components such as Linewidth 1 pe x variables whose histories i LineColor ai select you want to view Line Width Marker Indicate Line Color These set the width and color of the lines in the graph Marker When you select this check box markers are displayed on the graph If you want to display multiple graphs on the screen at the same time you need to add each of their components such as agent 1 agent 2 variable 1 and so on as graph components In other words the corresponding number of elements must be arranged in the list You can select and edit existing graph components by clicking Edit You can also select and delete existing graph components by clicking Delete At Output Value in Graph Component List a numeric to surrounded by is unfolded example World Val 3 5 writes World Val 3 World Val 4 World Val 5 2 18 Agent Based Simulator User s Manual B
72. ent that detects agents with the same X or Y coordinate as the agent If neighboring Tree state Color_Green AND neighboringTree X My X OR neighboringTree Y My Y then 3 Rules for Jumping Sparks You can also make fire spread between trees that are not directly touching Jumping sparks usually occur only when the wind is strong so let s add this to the rule we created in 2 Fire06 abs Tree agent rule Agt_Step Dim neighbors as Collection Dim neighboringTree as Object Dim Stp as Integer If My state Color_Red then neighbors _CollectAround My X My Y 1 World twoDimensionalSpace World twoDimensionalSpace tree For Each neighboringTree In neighbors If neighboringTree state Color_Green AND neighboringTree X lt gt My X 1 then neighboringTree state_B Color_Red EndIf Next neighboringTree neighbors _CollectAround My X My Y 4 World twoDimensionalSpace World twoDimensionalSpace tree For Each neighboringTree In neighbors If neighboringTree state Color_Green AND neighboringTree X gt My X 1 then If Int RndQ 100 0 then neighboringTree state_B Color_Red Endif EndIf Next neighboringTree My state_B Color_Black World burntTree World burntTree 1 EndIf This rule uses the neighbors collection twice In the second use neighbors are collected with a scope of 4 and sparks jump from a burning tree to a distant agent with a probability of 1 in 100 A 32 Agent Based Simulator User s Manual
73. eshold value e Ability to change the starting number of turtles e Ability to quit the simulation when the turtles stop moving e Addition of a time series graph and the number of steps view A 2 1 Making It Possible to Change the Threshold Value The first thing we want to experiment with in this segregation model simulation is to see how segregation patterns change when we vary the setting threshold value The threshold value affects the value of neighboring occupancy rate the turtles can stand without moving For the first modification let s try making it easy to set the threshold value with the Control Panel window The Control Panel window is used mainly to directly manipulate the threshold values of agent rules However you should note that these cannot be implemented in the rules using only the Control Panel settings We ll use the following method which is a bit complicated A 8 Agent Based Simulator User s Manual e Create the variable to store the value you want to control directly under the World hierarchy e Rewrite the rules to reference the variable you created e Make the settings in the Control Panel window Creating the Variable Under the World Hierarchy Add a single new variable directly under pamen the World hierarchy Var Name Type to Double and leave Number of Var Type Integer Set Variable Name to Threshold Variable Dimensions at 0 Number of fo E 0 th D Arraysize o men
74. ew Variable buttons on the right side You can add a new component by choosing the corresponding New button then clicking anywhere on the canvas World Agent World agent exists uniquely at the highest level of a simulation model All other components 1 10 Agent Based Simulator User s Manual are placed in the hierarchy under the World agent to make up the simulation Its name is World but it doesn t necessarily have to take up space as in the real world It s also possible to construct abstract models that take up no space Control Panel Control Panel has buttons for running stepping through pausing and stopping simulations If you click the Run button when only an empty agent rule has been made that is immediately after you go to the menu bar pull down the File menu and select New then not only nothing is displayed but the Tree and Canvas are hidden To return to the original state click the Stop button Untitled ABS File Edit View Add Settings Run Playback Window Help Ceh tse Canvas WORLD eee a Select New Space New Agent amp New Var Space This is the space where agents and variables are placed The present version of Agent Based Simulator supports only two dimensional spaces but support for three dimensions may be possible in future versions Normally you use the Grid Model with its regular horizontal and vertical arrangement but you can also use the Hexagon Model which
75. f Next neighboringTree My state Color_Black EndIf The collection makes its appearance in the Step rule The rule in this example says that if a tree s own State is burning red any neighboring trees in the eight adjacent locations also become burning red The collection is used for this neighboring portion The first section has Dim statements that define the variables In addition to the collection variable an object variable as Object also makes an appearance An object variable is used to call objects from among a collection In most cases however an object is an agent The _CollectAround function appears in the subsequent block This function groups agents objects in a range centered on specific coordinates into a collection You may have noticed that the method used to specify it resembles that for _ViewCountAgent which we saw in an earlier section However whereas _ViewCountAgent can only return the number of agents a collection can perform processing that is more complex gt Group the neighboring agents into a collection _CollectAround X Y range space name agent name Notice the For Each in the next line This is a special way of accessing each individual element of a collection That is to say For Each neighboringTree In neighbors indicates that the elements in the neighbors collection are to be sequentially read one by one as neighboringTree objects gt Sequentially access the elements i
76. f procedures and its results and supplementary explanations For example 1 Select Agent Based Simulator gt Description of procedure Agent Based Simulator starts gt Operation result Explanations after Important This provides additional explanations or special attentions This manual also assumes a basic understanding of the operations and terms of Windows If you are unfamiliar with how to use Windows refer to the documentation that comes with Windows 0 4 Agent Based Simulator User s Manual Chapter 1 An Introduction to Agent Based Simulator 1 1 Running the Samples Agent Based Simulator ABS includes two types of sample simulations that enable you to see for yourself how the program works You can start a simulation right away simply by opening the corresponding job file abs and making a minimum of settings Now you re ready to start learning how to use this multi agent simulator as you try it out for yourself Getting Ready To start a simulation the first thing you need to do is to start the multi agent simulator and select the job file for the corresponding model From the Start menu choose Programs go to Agent Based Simulator then to Tutorial and select either Sugarscape Model or Segregation Model This automatically starts Agent Based Simulator 1 1 1 Segregation Model A Simulation of Segregated Living Among Turtles 1 About This Simulation This is a model that simulates the p
77. gent eee eeeeeeeeeeneeeseeeeeeeeseeeeeeeees 1 23 1 4 6 How to Specify Components 000 0 eeceseceeeseeeeceeeseeeseeeseeesaecnaecaecneeeeeeseneeeaes 1 24 1 4 7 Accessing an Individual Agent cece ceecccseeeseeeneesseceseceeeesseeeaeesaecesecneeeeneesaes 1 24 1 4 8 Running It A Large Number of Regular Turtles 00 eeeeeeseeeeeeeeeeeeeee 1 24 1 5 Adding Random Factors to Agent cceesceceesseceeeseeceenteeceeneeeeenaeeeees 1 25 1 5 1 Placing Agents Randomly in a Space 00 0 ee ee eeeeeseesseceseceseceeceeeeeseeeseeeeneeeaes 1 25 1 5 2 Adding Random Factors to Variable Values 0 esessceseceseceseceeeceseeeneeeeeenaes 1 25 1 5 3 Changing Execution Rules for Agents ce eeceecceeeeeseeseeeeecneeceaecnaeseeeeeneesaes 1 26 1 6 Creating a Space That Wraps Around cceesceceesecceeneceeneeeeeneeeens 1 26 1 6 1 Space Component Settings ee ceeceeceseceseesseecseecssecsseceseceseeeeeeeneseseeeneeenaes 1 27 1 6 2 Creating a Function to Adjust the Coordinate Position eee esceseceeeceeeeeee 1 27 ETIO TE ERIO t sci ios canted a E E tae E S E E EEE 1 28 C71 Teinsa nd Techniques iiiter esisto a een atanena a a aE aeia eaea 1 29 F72 Lets REVIEW soninn a a i a i e aaa era Ae 1 29 1 7 3 Differences in Notation between Visual Basic and Agent Based Simulator 1 29 Reference 2 1 Making Settings for Models s serc k ccs whocestagiadic deen aiinaeinh at aoeeaaeie 2 2 24 1 Job File Input and Output nesccsccesecsscs
78. gent rules and World rules for instance a function generating a random number in a certain range gt Common rules can be referenced both from agents and from World Let s consider how to place Turtle agents with their X coordinates spaced three sites apart World need to know the number of agents created and to assign the values to the X variables for each turtle agent Write this into the Agt_Init rule for World 1 22 Agent Based Simulator User s Manual Prog06 abs World agent Agt_Init Dim ias integer for i 0 to_CountAgent World space turtle 1 World space turtle X i 1 3 nexti 1 4 3 For Variables Used Only in Rules First Define the Type What appears first is a Dim statement This is called a declaration statement It s used to define a type for a temporary variable used only within a rule When execution of the rule ends the variable is deleted Such variable is called local variable Local variables are used differently from variables in the component tree which continue to maintain their value Here we ll define a variable of Integer data type called i for accessing an individual agent gt Temporary variables local variables used only within rules are declared with a Dim statement 1 4 4 Loop Control The next topic is the For Next statement This is called a loop control statement It s used to repeat the enclosed commands the specified number of times The number of times is specified as fo
79. gents according to the tree density set at the Control Panel window and randomly places the required number of agents using _CreateAgent Fire01 abs World rule Agt_Init Dim LimX as Integer LimY as Integer Dim 1as Integer Maxi as Integer LimX _GetWidthSpace World twoDimensionalSpace LimY _GetHeightSpace World twoDimensional Space Maxi Int LimX LimY World treeDensity 0 01 Fori 1 to Maxi _CreateA gent World twoDimensionalSpace tree Nexti _RandomPutA gent World twoDimensionalSpace tree False Agt_Step Writing the Tree Agent Rules Next we write the rules for the agents In the Initial rule first we set the agent s own State to unburned green Color_Green is a special method used to specify the displayed color on the map Because the displayed color takes the state variable we make such an assignment In the subsequent If statement if the agent is at the left edge then State becomes burning red Fire01 abs Tree agent rule Agt_Init my state Color_Green if My X 0 then my state Color_Red End If Agt_Step Dim neighbors as Collection Dim neighboringTree as Object Dim Stp as Integer If My state Color_Red then neighbors _CollectAround My X My Y 1 World twoDimensionalSpace World twoDimensionalSpace tree For Each neighboringTree In neighbors A 22 Agent Based Simulator User s Manual If neighboringTree state Color_Green then neighboringTree state Color_Red EndI
80. he execution rule Agt_Step you end up with Prog11 abs gt User defined function Function function name argument name As argument type As return value type Agent Based Simulator User s Manual 1 27 Prog 1 abs turtle agent Agt_Init Agt_Step if Int RndQ 5 0 then my DIRX 1 Int RndQ 3 my DirY 1 Int RndQ 3 endif my X FixX my X my DirX my Y RixY my Y my DirY Function FixX iX as double as double Dim LimX as double LimX _GetWidthSpace World space IfiX gt Lim lt X 1 then iX iX LimX Elself iX lt 0 then iX iX LimxX EndIf Retum iX Function Fix Y iY as double as double Dim LimY as double LimY _GetHeightSpace World space IfiY gt LimY 1 then iY 1Y LimY ElseIf iY lt 0 then iY i1Y LimY EndIf Retum iY Some unfamiliar functions appear in FixX and FixY _GetWidthSpace and _GetHeightSpace are functions that obtain the width and height respectively of the target space Using these makes it unnecessary to revise the rule when changing the size of the space In order to reduce errors and increase the general utility of rules you should use function to define constant values if this value can be changed in its properties dialog box gt GetWidthSpace returns the width of a space gt GetHeightSpace returns the height of a space To apply what you ve learned here rewrite the random placement of agents covered in section 1 5 1 using _GetWidthSpace an
81. ierarchical relationship 1 4 7 Accessing an Individual Agent Obtaining the information that an individual agent holds requires a bit of extra work This method of expression is also frequently used so you should remember how to use it To start with created agents are assigned sequential IDs beginning with 0 The variables in an agent are stored in an array and are called in the form of the variable name agent ID For instance The X coordinate of a Turtle agent having an ID of 4 is expressed as World space turtle X 4 Take a look at Prog06 abs The variable i starts at 0 is looped to the number of agents 1 and the value of ix3 is assigned to each X coordinate gt Agents are assigned sequential IDs starting at 0 Array variables When a large amount of data must be handled at one time naming each variable individually would be an onerous task When assigning the test scores in five subjects for ten people for example creating individual variables for each person and each subject such as Jal En1 Mal Sol Scl Ja2 En2 Ma2 So2 Sc2 would be too inefficient Moreover if the number of persons were to change it would become impossible to cope with the change Array variables are used in cases like this An array variable uses the form of variable name ID and can be referenced simply by supplying the ID number in the parentheses Applying to the test scores for five subjects as an example the array variables m
82. ight be Ja 1 En 1 Ma 1 So 1 Sc 1 Ja 2 En 2 Ma 2 So 2 Sc 2 With this method all we have to do is specify Ja i En i Ma i So i and Sc i and use the value of i with a For Next loop With Agent Based Simulator the variables that agents have are automatically made array variables Also when you add a variable to a space a two dimensional array in the form of a grid matched to the size of the space is created The two dimensional array is specified as variable name X coordinate Y coordinate 1 4 8 Running It A Large Number of Regular Turtles Now let s set the number of agents at six and try running the simulation You see that the turtle agents are arranged at regular intervals as specified by Agt_Init 1 24 Agent Based Simulator User s Manual 1 5 Adding Random Factors to Agents So far we ve covered how to assign regular initial values However the results still seem a bit mechanical and not much like multi agents Now let s try adding a random element to the initial rule 1 5 1 Placing Agents Randomly in a Space Placing agents randomly in a space is fairly simple In Agent Based Simulator we use the built in agent function _RandomPutAgent The first item in the parentheses specifies the agent to place The second item specifies whether placement of multiple agents in a single cell is permitted True or False Because all functions return a value the correct use is along the lines of i
83. in a collection _GetObject Returns the object at a specified position in a collection Returns the collection of agents around specified location _CollectAround gt coordinates Returns a new collection formed by merging two collections _MakeMergeCollection A with no redundant elements Returns a new collection formed by joining two collections _MakeJoinCollection bes redundant elements are permitted l Returns a new collection formed of elements objects which _MakeCommonCollection g are common to two collections Returns a new collection formed of elements objects which keDiffCollection are included in only one or the other but not both of two collections Returns a new collection formed by excluding elements in keDelCollection collection 2 from collection 1 Examines whether a specified object exists in the elements of a collection and returns an integer greater than or equal to zero _GetCollectionEntry representing a sequential number element number from the starting element of the collection or 1 if the object does not exist in the collection 3 14 Agent Based Simulator User s Manual 3 7 6 Space Functions Number eturns the horizontal width of a specified space eturns the vertical height of a specified space eturns the space on which a specified object rides 3 7 7 File Input Output Functions Function name _OpenFileCsv Open CSV file _ReadFileCSV Read on
84. ings for font style size that you make here 2 1 6 Deleting an Agent Click the agent you want to delete then from the Edit menu select Delete Alternatively right click the agent then from the menu select Delete 2 1 7 Creating a New Variable This creates a new variable for an agent You can create a variable under any agent 1 Open Canvas agent name Here agent name is AGENT_1 The following window appears Canvas AGENT1 Important If you have created an agent in the space variables named X Y and Direction are already created These variables indicate the agent s coordinates in the space When no space exists they are not created 2 Go to the toolbox and click the Variable button The button should appear to be depressed 3 Click the blank area in the Canvas AGENT_1 window 2 10 Agent Based Simulator User s Manual Var Property Agent Based Simulator User s Manual 2 11 4 A Variable Properties dialog box appears Var Property E xj Var Name FAR 1 Var Type Integer Number of fo E 0 th D Arraysize o Mer men Type Name Value range Boolean data type Boolean True or False String data type String 0 to 1 000 characters Integer data type Integer from 2 147 483 648 to 2 147 483 647 Real data type Double from 1 79769313486232 x 10708 to 4 94065645841247 x 10324 when negative from 4 94065645841247 x 10324 to 1 797693 13486232 x 1
85. ings so the wind blows from the left edge the fire spreads only downwind that is to the front and the side 5 directions and the fire does not spread to the rear 3 directions A 30 Agent Based Simulator User s Manual Fire05 abs Tree agent rule Agt_Step Dim neighbors as Collection Dim neighboringTree as Object Dim Stp as Integer If My state Color_Red then neighbors _CollectAround My X My Y 1 World twoDimensionalSpace World twoDimensionalS pace tree For Each neighboringTree In neighbors If neighboringTree state Color_Green AND neighboringTree X lt gt My X 1 then neighboringTree state_B Color_Red EndIf Next neighboringTree My state_B Color_Black World burntTree World burntTree 1 EndIf This is fairly simple You are just required the conditional statement that detect the five neighboring tree agents In this case the condition is satisfied only when the state is green and the X coordinate is not the agent s own coordinate minus one that is not upwind forest e ABS File Edit View Add Settings Run Playback Window Help Dae t sels Number output 1 S O x parameter LOST WOODS 796 RATE LOST WoODS 43 0 Control Panel gt wlfu m DENSITY WOODS 20 100 Simulating mrss Agent Based Simulator User s Manual A 31 You can also rewrite the rule to change the number of neghborhoods from eight to four In this case add the conditional statem
86. is makes a window like the one in the following figure appear Now let s try actually running it To run it use the Control Panel window From the View menu choose Control Panel This Control Panel has different buttons and sliders than the segregation model Let s take a look at these working from top to bottom Food Replenishment When the slider is all the way to the left food is replenished at the rate of one per step When it is all the way to the right food is replenished at the rate of one per every four steps Naturally the farther to the right the slider is the harsher is the environment for the ants Seasonal Change When you select this button the space is divided into an upper part and a lower part and food is replenished only in one part This simulates a lack of food in winter Every 60 steps the seasons in the upper and lower areas are reversed Number of Red Ants and Number of Blue Ants You can use these sliders to set the starting number of each type of ant from 50 to 200 The SugarScape ABS File Edit View Add Settings Run Playback Window Help Dah tS Ol S Control Panel E STOMACH e DIRECTION BLUE_ANT N_BLUE_ANT SEASON Agent Based Simulator User s Manual 1 5 settings for these sliders must be made before you start the simulation Let s give it a try In the Control Panel window click the Run button Did the following screen appear See for yourself how the settings on the Co
87. it rarely runs flawlessly the very first time Something almost always occurs for example the program may stop because of a syntax error or it may not run as expected Mistakes and errors are an unavoidable part of programming even for seasoned programmers However being able to perform appropriate troubleshooting when problems occur seems to lead to proficiency in programming faster than trying to prevent errors before they occur Computers Operate Through Logic People are ambiguous but computers operate entirely through logic Unless some very special steps are taken there are never any exceptions where a computer will depart from logic This Agent Based Simulator User s Manual 1 19 means that any computer error always has a clear cut cause If results are not as expected it is never a case of the machine being in a bad mood or not liking the operator To eradicate errors it is important first of all to isolate and identify the problematic area according to computer logic The examples below are some errors that beginners are particular likely to make 1 Syntax Errors in Rules If operation is different from what you expected or if a warning message appears the first to look for is a syntax error in one or more of the rules These errors are not limited to beginners Even skillful programmers frequently experience syntax errors caused by carelessness Remedy1 If Agent Based Simulator discovers an error before execution
88. le Under the World Hierarchy Create a single new variable under the World hierarchy For Variable Name enter treeDensity Set Variable Type to Integer and leave Number of Dimensions set at 0 Space Property Space Name Space Type Dimention B Size of x so T so Treating Edge Not Loop C Loop Var Property Yar Name DENSITY WOODS Var Type Integer Number of fo 0 th D Arraysize o Mer men Agent Based Simulator User s Manual A 19 Adding the Agents Under the Two dimensional Space hierarchy create a new agent and make the Settings for its properties For Agent Name enter Tree The agents are created when the simulation runs so set Number of Agents to 0 Adding the Agent Variables The agents need a variable to determine the state Under the agent hierarchy create a new variable For Variable Name enter State Set Variable Type to Integer and leave Number of Dimensions set at 0 A 20 Agent Based Simulator User s Manual Agent Property Agent Name e Number Var Property Var Name Var Type Integer x Number of fo E 0 th D ArraySize mee Adding the Two dimensional Map From the Settings menu choose Output then add 2D Map Setting Component of Two Dimensinal Map Comp Target woops Cancel Marker None C Selec C Filenan C Val Name for Agent C Fixed Color
89. le for the convergence condition happyTurtles immediately under the World hierarchy and effecting a conditional branch according to this variable A 12 Agent Based Simulator User s Manual Creating the Variable Under the World Hierarchy Add a single new variable immediately under the World hierarchy Set Variable Name to happyTurtles Variable Type to Integer and leave Number of Dimensions set to 0 Rewriting the Rules Var Property i x Var Name APPY TURTLE Var Type Integer Number of fo H 0 th D ArraySize 0 Mer men To create the agents add the following statements to the end of the World initial rule and in the execution rules _ExitSimulation is a function for ending a simulation Also note that the equal sign used in the If statement is Agent Based Simulator uses for assignment but in comparison and equality statements the doubled is always used Be careful because these are often confused gt End a simulation Use _ExitSimulation gt In equality statements in If statements use Seg03 abs World rule Agt_Init mn double equal sign e e e The portion up to here is the same as in the previous rule _RandomPutA gent World twoDimensionalSpace redTurtle false World happyTurtles World numberOfTurtles 2 Agt Step if World happyTurtles 0 then _ExitSimulation Endif World happyTurtles 0 Also add the followi
90. llows For variable name starting number to ending number Step increment per iteration looped operation Next variable name The loop statement variable i is ordinarily increased by one with each iteration so you can usually omit Step When Step 1 is used the value is decreased by one with each iteration When you write the looped operation indent with a single tab to make it easier to understand the structure 1 4 5 Determining the Number of Created Agents In Agent Based Simulator the special function _CountAgent is used to determine the number of agents created When certain data is given to a function the function returns a value as result Some functions are built in You can also define your own original functions With _CountAgent when you specify an agent in the parentheses the function returns the number of agents as an integer gt When certain data is given to a function the function yields a specific return value Agent Based Simulator User s Manual 1 23 1 4 6 How to Specify Components In specifying an agent in the parentheses the hierarchical relationship with World is expressed by separating the names with periods This means the Turtle agent is specified as World space turtle This method of expression is used in many places so you should remember it gt When specifying a component state the hierarchical relationship beginning with World gt Periods are used to indicate the h
91. long with a commercially available syntax guide The language used in rules is basically in line with that of Microsoft Visual Basic 3 1 Overall Structure of Agent Rules An agent rule is written with the following structure for each agent A rule is a collection of functions Agt_Init Local declaration block Execution block Agt_Step Local declaration block Execution block User defined function User defined functions are not necessarily required 3 2 Special Functions Agt_Init This is a function that is executed only once when agents are created while running a simulation The name Agt Init has a special meaning and Agt_Init is a reserved word that cannot be used for any other purpose The format is as follows Agt_Init Variable type declaration block Execution block Agt_Step This is a function that is executed repeatedly until the simulation ends The name Agt Step has a special meaning and Agt_Step is a reserved word that cannot be used for any other purpose The format is as follows Agt_Step Variable type declaration block Execution block 3 2 Agent Based Simulator User s Manual 3 3 User defined Functions You can freely define user defined functions Like name constants declared in the variable type declaration block functions defined here can be called from the Agt_Init function Agt_Step function or user defined functions in the relevant agent rule However that can
92. mulation partway through Execution Pause Time When one step ends processing pauses for the time specified by this value If you are using a fast computer and the simulation speed is too rapid then enter a suitable value here Random Number Seed You can specify a pattern for random numbers Agent Based Simulator User s Manual 2 25 Log File Tab Log File Name Simulation Setting xi Log File Name Format Sim Log runtype multi Report These set the name of the log file Clicking Set displays a dialog box for saving LogFile Name where you can specify a file m LogFile I name and location of the log S me file Fixed Logging Step Interval C Number When you enter a value C Date here logging to the log file is performed during execu tion of the simulation When Bego miegasul _ a the entered value is 1 log ging is performed at every step A log file having the name of your choosing abs is created You can play back the executed simulation by opening this file Run Sequence tab Agent Rule Run Sequence Simulation Setting xi Agt_Step for World is ex hegi Sim Lo runtype multi Report ecuted first in the step but a E you can use this screen to Order of Run AgentRule change the settings for Random Fixed Agt_Step for agents When you select Random the ex ecution sequence for agent rules is determined ran domly When yo
93. my is special notation pointing to the agent itself mn gt The equal sign in a rule is an assignment statement Agent Based Simulator User s Manual 1 15 Steps ABS simulations are executed in units of time called steps At each step all Agt_Step rules execution rules included under World are executed in random order When this finishes the step is incremented Untitled ABS File Edit View Add Settings Run Playback Window Help D W elal Control Panel turtle Simulating 1 3 8 Running It A Bullet Turtle that Disappears from the Map When you finish writing the rule go to the Control Panel window and click Run If there is an error check the highlighted line for an incorrect word When the program runs correctly the value of the X coordinate increases by 1 so the turtle on the left edge moves to the right side and finally moves off the two dimensional map and disappears from view Even after it disappears from the map the turtle keeps moving to the right so click Stop to stop it At the Control Panel window click Stop to quit the simulation From the menu bar click File to display the menu then choose Save As Name the program prog02 abs and save it 1 3 9 Making an Agent that Moves Back and Forth Over the Map 1 Adding a Variable to the Agent Now let s try modifying the bullet turtle rule reworking it so that the turtle now moves back and forth over the two dimensional map
94. n e Not plus linear expression Not is a bitwise operator e Expression Examples of linear expressions 0 Constant x Variable name x Variable name Function_a a b Function call x linear expression Function_a a b linear expression Nota Not plus linear expression a b expression a b linear expression The following summarizes the operators that can be use in expressions and their precedence 3 8 Agent Based Simulator User s Manual String operators Prece Type Operator ee Meaning 1 Expression enclosed in stots Function 2 Function call 3 Exponentiation x 4 Negation x z cages caps Arithmetic ae BA A SE Floating point division result is floating point number operators used 5 x in arithmetic y er a E 6 Integer division result is integer x y P Mod 7 Modulo result is remainder of integer division 8 Addition x y 8 Subtraction x y String operator amp 9 String concatenation ab amp cde abcde 10 equal note difference from s lt gt 10 Not equal identical to Relational LS 10 Not equal identical to lt gt operators used lt 10 Less than in relational T Gone lt 10 Less than or equal H gt 10 Greater than 2S 10 Greater than or equal Logical Not 10 Logical negation operators used And 11 Logical conjunction in logical Or 12 Logi
95. n the collection For Each A Object in B Collection Next A The state variable of the neighboringTree object is read and if the state is unburned green then it is changed to burning red As with My it can be accessed simply by using neighboringTree state A 3 2 Synchronizing the States Using a Backup Now the preparations are complete let s try executing it After you ve run it a few times you ll probably notice that the results are different from those of simulations made with StarLogo If the spread of fire from the left edge per unit time is taken to be equal then when 100 of the ground is covered by trees the fire should spread to the right linearly and uniformly But that s not what happens in this simulation Why not The reason has to do with the specifications of Agent Based Simulator which prevent it Agent Based Simulator is a simulator for multi agent models but when the computer performs the processing internal processing for each individual agent must be carried out singly and sequentially even for multiple simultaneous events This processing order is allocated randomly for agents other than the World agent This means that depending on the sequence of agent processing it s possible that a state to be read in the next step in this rule burning red may be read by another agent in the selfsame step resulting in chained processing Agent Based Simulator User s Manual A 23 If you want to ens
96. ng back 2 32 Data manipulation function 3 13 M Debug screen feature 2 40 Marker view A 5 Model 0 3 Dim statement 1 23 Dimensions ty description 2 40 number of 2 12 DORI i importing description file 2 10 Disk1 0 2 _MoveToSpace A 7 Multi agent 0 2 Do Until statement 3 11 Do While statement 3 10 My variable name 1 15 Dummy statement 3 6 2 Index amp Information Naming method 3 4 Numerical calculation function 3 13 Numerical screen adding output A 16 output settings 2 22 Output item list 2 16 Output screen keep after running 2 10 Output setting adding 1 12 setting output value A 15 _RandomPutAgent 1 25 Replace feature 2 8 Report output tab 2 29 Reserved word 3 15 Return statement 1 27 3 12 Return value type 3 3 RndQ 1 25 Rule editor setting 2 9 displaying window 2 7 Run continuously tab 2 27 Run sequence tab 2 26 Segregation model 1 2 A 2 Set default 2 16 Simulation tab 2 25 when doesn t run correctly 1 19 Space 0 3 1 11 creating 1 12 2 5 new 2 3 number of dimensions 2 5 function 3 15 name 2 5 properties 2 5 size 2 5 type 2 5 Step 1 16 Sub statement 3 3 user defined statement 1 27 Sugar model 1 4 Time series graph adding A 14 output setting 2 16 Tool box 2 3 adding item to 2 4 Tree 1 2 1 10 2 3 Two dimensional view map output setting 2 20 Type conversion functions A 29 Variable 0 3 1
97. ng statements to the redTurtle and blueTurtle execution rules These add 1 to the World happyTurtles variable when the turtles stop moving Agent Based Simulator User s Manual A 13 Seg03 abs Red turtle and blue turtle agent rules Agt_Step e e e The portion up to here is the same as in the previous rule if my happiness lt World threshold then _MoveToSpace my X my Y 3 Else World happyTurtles World happyTurtles 1 endif The usage of the World happyTurtles variable in the World agent is a bit tricky That s because this variable is set to zero right after the conditional statement that ends the simulation if the value of the variable is zero It seems that a simulation should stop immediately but in reality it works well Why is that It s because rules are always execute in the sequence of first the World agent and then the various other agents This means that even though the variable is set to zero at each step the movement numbers are added according to the agent rules and are carried over to the next step If the value of the variable remains zero in a particular step the conditional branch at the beginning of the next step ends the simulation A 2 4 Adding a Time series Graph and Step View In the previous step we added the happyTurtles variable to World If we could graph this numerically we would be able to know how many turtles move in different steps Accordingly now let s try adding a time series graph an
98. not be called from agent rules for other agents The format is as follows Function statement Function function name parameter declaration As function return value type Variable type declaration block Execution block Return expression Function This declares that a user defined function is defined starting here Function name You can name this any way you like However reserved words or already declared variable names and name constants cannot be used because these may confuse Agent Based Simulator As function return value type This is stated when the function must return a value When this is omitted the function cannot return a value For the function return value type specify the type of the value that the function returns The method of specifying this is the same as for the variable type Sub statement Sub function name parameter declaration Variable type declaration block Execution block Sub This declares that a user defined function is defined starting here Function name You can name this any way you like However reserved words or already declared variable names and name constants cannot be used because these may confuse Agent Based Simulator Agent Based Simulator User s Manual 3 3 Parameter Declaration When a parameter is passed to the function the following format is used to declare it Variable name I As variable type Variable name n As variable type
99. nsccsseesstecetiaves ai a a a a a E 2 2 2 1 2 Creating a New Job Fil nsiasisiotier ctscdeiectagl oveibtageonl anae a et iaiia aiaei 2 3 2 4 3 Creating a N w Spate oasinnmar ieaiai ec tent eia eia on 2 5 214 Creating a New Agent vccecciviced eeseseisiescdecsaaagneebess a E ENEE EE EE EE 2 6 21 5 Writing the Agent Rules eroe enitrrps seni Aaa E ELER 2 7 21 0 Deleting an Agent necreti eai e E ER EE TEE E bee Bas 2 10 2A Creating New Variable aciscesccissccctaetidotaccbessscacesbatecsaebuanestoblodegesiyloidgebeaieSeaes tate 2 10 2 2 Simulation Setting Feature secs nasusdst anata aoweueexuntasctaiad 2 13 2 21 Initialize Dialog Box sssvcstes cocgesea cette Get veetecliecdentaeadebdavedsisabease EEEE EEEa 2 13 2 2 2 Set Default Dialog BOX cs cvecccscadecceuhens eii E EE ENEE EE 2 16 2 2 3 Output Settings Dialog BOX erein ereit ana aeria ai aia 2 16 2 2 4 Execution Environment Settings Dialog BOX sssssesessreereererrerrerreresrsrerresrrsreere 2 24 22 5 Control Panel Settings en e tote E ati e a e 2 29 2 3 Simulation Execution Eatress ici vusmcesarin weasidatcasitvaeicauitionles 2 31 ZA Tos Play Pack Meare yale yess etly acess saci at eb vs ecco ns hes esi oy od Sosa en Soyo 2 32 2 5 Analytic File Output Feature sy se cy seit crews eee hebeeneeega alee nantes teeter Rane 2 34 2 6 Help Feat E tenun aaar ieee asta r dim AAE 2 40 2 1 ADE DUS Screen Feat re arrora niria EEEE stasis 2 40 Agent Rule Syntax 3 1 Overall Structure of Agen
100. nt creates a single instance of the agent specified in parentheses Combined this with the For Next statement create a total of World numberOfTurtles x 2 turtle agents Agent Based Simulator User s Manual A 11 Making the Settings for the Control Panel Window From the menu bar select the Settings menu and choose Control Panel Settings When the Control Panel window s User Setting List dialog box appears click Add se 4 xj Control N_TURTLE Target N_TURTLE Traoi Interface C Button Toggle Range 200 to 700 Spacing 50 Slide Bar Input When the User Settings dialog box appears set Control Name to Number of Turtles and Setting Target to Number of Turtles For Interface choose Slider Set Range to 200 to 700 and Scale Interval to 50 When you ve finished making the settings click OK to close the window The User Setting List dialog box closes gt Create agents Use _CreateAgent agent name A 2 3 Quitting the Simulation When the Turtles Stop Moving One drawback of the simple model is that the simulation continues to run on and on even when the locations of the turtles become more or less static This means that you can t determine when at what step convergence occurs unless you constantly watch the simulation For that reason let s try revising the program so that the simulation quits automatically when the turtles stop moving We ll use a method that involves creating a variab
101. nt up to a length of 256 characters What you enter here has no effect on the simulation so you can use this area for making notes 4 Click OK to close the dialog box A space appears on the canvas Agent Based Simulator User s Manual 2 5 Now you ve established a space immediately under the World agent Important You can only create a space immediately under the World agent ABS is designed that way to keep things conceptually easy to understand 2 1 4 Creating a New Agent This section describes how to create a new agent in a space Unlike space agents can be created immediately under the World agent or other agents The example here shows how to create an agent in a space Open Canvas space name Here space name is SPACE_1 You can use any of several techniques to open the canvas e Double click a component in the tree or on the canvas e Right click a component in the tree or on the canvas then select Canvas from the menu e Select a component in the tree or on the canvas then choose Canvas from the View menu Click the Agent button in the toolbox The button should appear to be depressed 3 Click anywhere inside the Canvas SPACE _1 window The following Agent Properties dialog box appears Agent Name Agent Property f x Enter the agent name you want Agent Name Number of Agents Enter the number of instances of this Number f agent The number you enter here is used Me
102. ntrol Panel affect the simulation 1 2 Making Changes In the previous section you tried running some models yourself but that was only able to run prepared simulations Now let s try getting some different results by changing the settings 1 2 1 Segregation Model A Simulation of Segregated Living Among Turtles Making the Component Settings Again Changing the Type of Space In the initial stage the turtles moved around on a square grid measuring 35 squares on a side Let s try changing this to a hexagonal model The procedure is as follows In the Tree window right click on twoDimensionalSpace From the menu select Properties Click Type of Space then change Grid Model to Hexagon Model In the grid model the turtles could only move in four directions forward backward left or right But in the hexagon model they move in six directions SugarScape ABS Doel S Control Panel ANT MAP 1 4 0 2 FOO Oj REDAN SEASON BLUE aaun RED ANT s0 200 BLUE_ANT Simulating 1 6 Agent Based Simulator User s Manual Making the Output Settings Again Next let s try modifying the output in various ways From the Settings menu choose Output 1 Making the time series graph lines bold and adding markers Let s add markers to the apices of the bends Space Propeetl x in the lines of the time series graph and make the lines thicker making the graph easier to Space Name J
103. odel Using Internal Functions Simple Segregation Model Let s try constructing a segregation model This is a classic topic in the field of multi agent simulators put forth by Thomas Schelling This is based on a rule discovered by Schelling in his studies of the living patterns of residents in urban areas It says that ethnic groups or races that initially live in an ethnically mixed state become clearly segregated over time Various features have been added to the model included with the tutorial to make it easier to use so we ll start by implementing a simple segregation model having only a minimum of elements The rules that define the segregation model are as follows 1 There exist equal numbers of two types of turtles red turtles and blue turtles 2 The maximum occupancy of a single cell is one turtle Two or more turtle cannot exist in a cell at a same time 3 A turtle receives information from turtles in the eight cells surrounding it and knows what percentage of the turtles are the same type as itself this is the degree of happiness 4 When a turtle s happiness is lower than a threshold value the turtle moves to a nearby vacant cell 5 When a turtle s happiness is higher than the threshold value the turtle does not move The required parameters for the simple segregation model are as follows 1 The numbers of red turtle and blue turtle agents are 500 each 2 The threshold is 0 6 60 A 1 1 Preparing the Simul
104. onents C Every Step to the report file Output Output Value Enter the variable you want to output Decimal O This sets how many digits to the right of the decimal point are output Show Fractional Numbers 2 2 5 Control Panel Settings Control Panel is used to start a simulation pause a simulation partway through or quit a simulation You can also change the variables immediately under World while execution is in progress To start a simulation click the Run button To quit a simulation click the Stop button To pause a simulation click the Pause button Agent Based Simulator User s Manual 2 29 Clicking the Step button executes the simulation one step at a time Each click of the button executes one step after which the simulation pauses Making Settings for the Control Panel To make settings for the Control Panel go into the Settings menu and select Control Panel Settings Control Panel List of user settings z bd z Add Edit Delete Add This adds setting items displayed in the Control Panel window Edit This is used to edit existing setting items Delete This is used to delete existing setting items Clicking Add or Edit displays a User Settings dialog box Control Name User Setting Component Enter an easy to Control GROWTH RATE understand name of your choosing in this Target GROWTH_RATE xj Cancel setting Interface Setting Target e patton
105. orrect Component Properties If there s nothing wrong with the rules but operation is nonetheless incorrect it s necessary to look for an error in the properties of the components such as the number of agents created and their initial values 1 20 Agent Based Simulator User s Manual Remedy 1 Make sure the value of each property is set correctly Remedy2 Remember that there are a number of methods for determining the initial values of components e Batch settings of numerical values for all components are made with Set Default e Numerical values of individual components are set separately with Initialize e Numerical values can also be assigned by assignment statements in the component rules When initial values are set using all the preceding methods the settings take priority in this sequence 1 component rules 2 Initialize and 3 Set Default Make sure that the values of the settings are not being changed somewhere 1 3 12 Conclusion Here is what you ve learned in this section 1 3 13 Terms and Techniques Component tree Canvas World agent Control Panel Space e Agent Variable e Adding space to World Adding agent Adding output settings Displaying Rule Editor Two types of rules Agt_Init and Agt_Step How a component references itself my Conditional branch statements If Then End If Adding variables to agents Creating multiple agents
106. osition What we need to do now is to prepare another rule to adjust the coordinate position of the agents However because the rules themselves are starting to get lengthy and because we ll be able to find other uses for this adjustment rule let s try using a user defined function A user defined function is a function that you can define any way you like You use Function or Sub for this Function and Sub are differentiated in use as follows e When a return value is required 00 Function e When a return value is not required SubQ User defined statement format for Function Function function name argument name as argument type As return value type variable type declaration block execution block Return variable name User defined statement format for Sub Sub function name argument name as argument type variable type declaration block execution block Important You can give a function any name you like except reserved words already declared variable names and already declared name definitions Using such illegal names can cause Agent Based Simulator to become confused Because the adjustment rule requires a return value we have to use Function statement You can write it at any location in the Rule Editor except inside Agt_Init or Agt_Step Add the following user defined function after Agt_Step for the Turtle agent When you then eliminate the map edge processing portion from t
107. pe to Double data type and leave Number oF fo the number of dimensions at 0 E 0 th D ArraySize Mer Adding the Two dimensional Map From the Settings menu choose Output then add 2D Map Two Dimensinal Map Settings WORLD BASE i P BASE Title Cancel Exp Notes _ Ruled Line V Background J gt Setting of X Axis Setting of Y Axis Axis SY Axis Min fo Min fo Max 3a Max 3a Map Component List Lu La L gt Lob Add Edit Delete A 4 Agent Based Simulator User s Manual Set Map Name and Map Title to Two dimensional Space At the Map Component List click Add to add the component Setting Component of Two Dimensinal Map d x Target RED_TURTLE z Cancel Marker None Selec a C Filenan C Val Name for Agent Fixed select Color C by Var Var Informatio Indicate When the Two dimensional Map Component Settings dialog box appears set Compo nent Name to Red Turtle and set Output Target to Red Turtle as well clicking the drop down arrow displays the options Leave Marker none and set Agent Color to Fixed Color If the color is not red then click Select and choose the right color Leave Agent Variable Information un selected Follow the same steps to add the Blue Turtle component Be sure to modify the settings for Output Target and Agent Color correctly or what s displayed will not be right Ma
108. r to create instances of agents acting according to the same rules In other words this is the number of copies of identical agents Note You can any text you want up to a length of 256 characters What you enter here has no effect on the simulation so you can use this area for making notes 2 6 Agent Based Simulator User s Manual 5 Click OK to close the dialog box The agent appear on the canvas Canvas SPACE 1 E x Now you have created a new agent immediately under the space You use the same procedure to create a new agent immediately under the World agent or another agent Important When you put an agent in a space the three variables X Y and Direction are automatically placed under the agent These variables contain the coordinate information for the agent 2 1 5 Writing the Agent Rules After you create an agent it doesn t do anything without rules for it You need to write agent rules for each agent 1 Choose an agent and open the Rule window There are three types of Rule windows the World Rule Editor for writing rules for the World agent the Agent Rule Editor for writing rules for other agents and the Common Rule Editor which can be referenced from anywhere To open the Rule Editor select an agent then go into the View menu and choose Rule Editor or Common Rule Editor Alternatively right click the agent then select Rule Editor When you do this the following window appea
109. rker View The feature that displays the agents on the two dimensional map as circles triangles xs or other shapes is called Marker View If you don t use Marker View agents appear as squares aligned with the cells Agent Variable Information In some cases you may want to have direct knowledge of the state of variables under an agent s hierarchy You can display variable values in the center of the agent view by selecting Agent Variable Information Agent Based Simulator User s Manual A 5 When you ve finished making the settings close the Output Item List dialog box Now you re done preparing the simulation components E S RED_TURTLE x By DIRECTION HAPPINESS E S BLUE TURTLE T x y DIRECTION d HAPPINESS A 1 2 Writing the Rules After you ve structured the components for the simulation the next step is to write out the rules In a simple rule the World rule is also simple the initial rule just places each agent randomly Notice that false appears at the end of _RandomPutAgent This indicates whether it is permitted to place multiple agents in a single cell The rule for this model place no more than one agent per cell so this is set to false Seg01 abs World rule Agt_Init _RandomPutA gent World twoDimensionalSpace blueTurtle false _RandomPutAgent World twoDimensionalSpace redTurtle false Agt_Step Next let s look at the Red Turtle agent rule The
110. rocess by which two types red and blue of turtles move according to certain rules resulting in segregated living There are no differences in the personalities or other traits of the two types of turtles When a turtle is surrounded by certain number of other turtles it moves to an unoccupied space to seek more comfortable surroundings This is the only rule established for the turtles but it results in segregated living among all the turtles Of course you can change these settings any way you like but first try running it with the original settings 2 Settings Going into the Tutorial folder and opening the Segregation abs file makes a window like the one in the following figure appear Tree This is the most basic screen for this simulator It displays the hierarchical structure of the 1 2 Agent Based Simulator User s Manual Segregation 4BS File Edit View Add Settings Run Playback Window Help DOSH eB Control Panel E BASE 3 RED_TURTLE a HAPPINESS a N_TURTLE gt LIMIT HAPPY TURTLE SUM_HAPPINESS various components One agent the World agent always exists in the tree Other components such as two dimensional space agents and variables exist under it These are explained in later chapters For now just think of it as something like Explorer in Windows Now let s try actually running it To run it use the floating Control Panel shown below Control Panel This window is used to con
111. rs Agent Based Simulator User s Manual 2 7 Rule Editor AGENT 1 Jaet hit Find z gt_hit gt_Step 2 Write the agent rules inside this window For Agt Init write between the and the rules that are to be executed only once when the agent is created For Agt Step write between the and the rules that are to be executed at every step of the simulation Search and Replace Features While the Rule Editor is open go into the Edit menu and select Find or Replace to display the Find or Replace dialog box 1 Find screen aixi O E J Match whole word only Cancel Match case 2 Replace screen Replace TS Find what Turtle Replace with Jant Replace Replace All J Match whole word only Cancel J Match case cres Important Existing multi agent simulators have had a serious drawback simulations cannot be constructed unless the user masters an extremely difficult programming technique The development of Agent Based Simulator addressed this point However in order to 2 8 Agent Based Simulator User s Manual enable you to construct simulations and make settings for rules as freely as possible the writing of programmatical rules is kept to the minimum necessary To learn more about rules study rules such as those in the sample models The format of the rules used in Agent Based Simulator is based on the syntax of Microsoft Visual Basic
112. rule for red turtles is as follows Seg01 abs Red turtle agent rule Agt_Init Agt_Step Dim redTurtleNumber as integer blueTurtleNumber as integer turtleTotal as double redTurtleNumber _ViewCountAgent my X my Y 1 World twoDimensionalSpace redTurtle 1 blueTurtleNumber _ViewCountA gent my X my Y 1 World twoDimensionalSpace blueTurtle turtleTotal redTurtleNumber blueTurtleNumber If redTurtleNumber gt 0 Then my happiness redTurtleNumber turtleTotal Else my happiness 0 EndIf A 6 Agent Based Simulator User s Manual if my happiness lt 0 6 then _MoveToSpace my X my Y 3 endif Take a close look at the Step rule The first line defines variables used only in the Step rule In the following block the number of neighboring red turtles and blue turtles is counted and the total is calculated In the third block the neighboring occupancy rate for red turtles is calculated and in the fourth block if the rate is less than 0 6 a move to an unoccupied cell is effected There are two new functions related to agents The first is _ViewCountAgent This function returns the number of agents in neighboring cells Its usage is _ViewCountAgent X Y range agent name For X and Y you ordinarily specify the coordinates of the agent itself In specifying the range the agent s own location is 0 to move outward in successive neighboring steps you add 1 for each step For example when you specify a
113. s a programming technique for obtaining a result that is only either 1 or 1 gt i Int Rnd a 1 obtains a random integer from 0 to a Agent Based Simulator User s Manual 1 25 Prog09 abs World agent Agt_Init Dimi as integer For i 0 to _CountAgent World space turtle 1 World space turtle X i Int RndQ 50 World space turtle Y i Int RndQ 50 World space turtle DIRX 1 int RndQ 2 2 World space turtle DirY i 1 int RndQ 2 2 Nexti Prog09 abs turtle agent Agt Init 1 5 3 Changing Execution Rules for Agents Now you ve assigned the agent s location and orientation randomly Next as a practical application of this let s try adding a random factor to the agent s execution rules Agt_Step In our programs so far the direction changed only when Turtle agents reach to edge of space Now let s make the orientation change randomly In the execution rules for the Turtle agents Agt_Step write a rule to change the direction at random before the determination of whether a border has been reached Prog10 abs turtle agent Agt_Step if Int RndQ 10 0 then my DIRX 1 Int RndQ 3 my DIRY 1 Int Rnd0 3 endif if my X lt 0 then The rest is the same The direction changed each iteration the agents would zigzag all over the place so we added an If statement to make the direction change only one time out of ten on average Unlike the earlier example the If statement obt
114. t Rules snsonsesessseeeseeseresseesseesseesseeseeessesserese 3 2 32 Special FUNCHONS oe cess cs ia an d a i 3 2 3 3 Userdefined FUnctionS esenea Ea E E a Seat 3 3 DA R les f t NAMES isror iaaea Gann eed EE E TE 3 4 3 5 Variable Declaration Block cicsvssiccecawnsiiasecsenvenvedacabeavaives concdasedayecransbaeatveds 3 5 3 5 1 Declaration of Variables 0 ccccc cc cccecssessscccccccesssssscsccccccssssssssessccseesssssscsseseseseaes 3 5 3 5 2 Variable Type Declaration ii iscciistssectulstacebessegpeencediebh loca cos a eA eS TEE aE eN 3 6 3 0 Exec tion BIOCK sie eee a A EE E A ERE 3 6 3 64 Dummy Statement9 si enni sena a i saen 3 6 3 6 2 Assignment Statements siei r E e E e EE ees 3 7 3 6 3 EXPIESSIONS an o ee a a ides aa aa r e a R TEN 3 8 36A Function Calls ee nehire ieie ies ia e e ity A E E E EEE 3 9 3 6 5 Conditional Statements eccsecorinnio nin ninien e e i e 3 9 3 6 6 Loop Stat6ments rasni ea a a a E ee eee 3 10 3 6 7 J mp St tements en r e e a EN E E EAEE 3 11 3 6 8 Other Statements reenn a a a er a aR 3 12 3 1 Intemal FUNCHONS raeth EEEE TE E E EE 3 12 3 7 1 Numerical calculation Functions sseeessseeeeeeessesesseeresresresrestesresteseesrrrisseerrereesene 3 13 3 7 2 String manipulation Functions seeseeseseeseeeesesseseseesesresrestestsresresrestesrssesesresessee 3 13 3 7 3 Data manipulation Functions 2 0 cece eesceseeseeeeeececeeceeceseeeseesaeceaeeseeeeneesaesnaees 3 13 3 7 4 Agent
115. that are required during execution The ones we need here are Step Number Burned Tree Agents and Burnt Rate You can get the step number using _GetCountStep For Burned Tree Agents create the variable immediately under World and increment it when an agent changes to the burnt state Adding the Variable Under the World Hierarchy Create a new variable under the World hierarchy For Variable Name enter burntTree Set Variable Type to Integer and leave Number of Dimensions set at 0 A 26 Agent Based Simulator User s Manual Rewriting the Tree Agent Rules Now rewrite part of the tree agent rules Var Property Change them to add 1 to the l Var Name MEDE World burntTree variable when a tree is burnt Var Type Integer Number of fo E Oo th D ArraySize Mer cacet_ Fire03 abs Tree agent rule Agt_Step e e e The initial rules and execution rules up to here are the same as in Fire0Q2 abs For Each neighboringTree In neighbors If neighboringTree state Color_Green then neighboringTree state_B Color_Red EndIf Next neighboringTree My state_B Color_Black World burntTree World burntTree 1 e e o Add this line EndIf Adding Numerical Screen Output to the Output View From the menu bar select the Settings menu and choose Output When the Output Item List dialog box appears select Numerical Output as the output type to add then click Add When the Numerical Screen Output Settings dialog box appe
116. the list You can select and edit existing numerical screen output components by clicking Edit You can also select and delete existing numerical screen output components by clicking Delete 2 22 Agent Based Simulator User s Manual File Output Settings File output saves a log of the simulation to a file When you select this with Output Type to Add the following dialog box appears Output File Setting Output File output 1 Filename JoutFile txt Cancel Output 1 Every Breakpoiin Tab C Comma C Space C Other Output File Component List Ld La lo Le Add Edit Delete Output Name This is the name references when this file output is called File Name This is the file name for output The default is OutFile out To change the file name click Settings and change the setting Output Interval This sets the timing for output to the file Separator This selects the separator character for output data Agent Based Simulator User s Manual 2 23 File Output Component List Add Clicking the Add button for File Output Component List displays this screen Component Name Output File Component List E x In this field you can give Componentjelement_ 1l L the file output component a name of your choosing Output Cancel Output Value Enter the variable you want Decimal to output Show Fractional Numbers This setting determines how many digits to the right of the d
117. the nth dimension Examples x Fora one dimensional array y Fora one dimensional array zj Fora two dimensional array 2 For an agent variable agent name variable name Agent name This states the path name of the agent Examples I Example 1 When specified with the relevant agent as the origin Up Up agent_b Up Up one level in the hierarchy Example 2 When the agent is an array World agent_a i Agent_b I Example 3 When specified with the World agent as the origin world Agent_a agent_b i Example 4 When specifying the relevant agent My Agent Based Simulator User s Manual 3 7 Variable name The format is the same as for variables declared within an agent rule Examples of assignment statements a 0 a b c a b Function_a c a i b World a 0 World a i b c i World Agent_a i b c My a 1 3 6 3 Expressions An expression is a linear expression or linear expressions joined by operators including the following types e Arithmetic expression x y RndQ 10 e Relational expression Ifx gt y Then e Logical expression s Ifx gt y And x gt z Then e Character expression multi_agent multi amp agent A linear expression may be any of the following e Numeric constant e Character string constant e Variable name the same as a variable name in an assignment statement e Function call e linear expressio
118. ting Enter the step count you want to output data Agent Based Simulator User s Manual 2 35 Output Values Setting Set values for output data Select an Agent show values series click Add button for ouput values displays this screen You can select many values Clicking Delete button to except entries Click More button you can set for details 2 36 Agent Based Simulator User s Manual Enter Side Format C Val Step C Simulation Cov ees Rie a es Side Format Setting Set side format for output data Agent Based Simulator User s Manual 2 37 Enter Header Format Value fs Step count C Simulation ci Header Format Setting Set header format for output data 2 38 Agent Based Simulator User s Manual Options setting Output File data txt gt Header output Yes C No ride output Yes C No Comma C Space Tab r Individuals settircLost Agent Output setting Space 2 specified C None Output file Set file name for output data Header Output Set Header format for output data Side Output Set Side format for output data Separator This selects the separator character for output data Deficit Data This selects the deficit data for output data Agent Based Simulator User s Manual 2 39 2 6 Help Feature Descriptions of Models If a model description file is
119. tree right click on World to display the context menu Then select Add Space Selecting Add Space displays a Space Properties window Set Space Name to space set Space Type to Grid Model leave the Space Size settings at 50 for both X and Y and set Edge of Space to Do Not Loop When you have finished making the settings click OK to close the window Now you re done creating a two dimensional space using the grid model for the World agent Make sure that space appeared under World in the tree and on the World canvas 1 3 3 Adding a Component Agent In the Tree window right click space From the context menu choose Add Agent The Agent Properties window appears Change Agent Name to turtle and set Number of Agents to 1 When you have finished making the settings click OK to close the window This creates a turtle agent in the hierarchy under the space When you click the of the turtle agent on the tree you see that the variables included in the agent have been added automatically X and Y indicate the coordinates of the agent s location in the two dimensions with the upper left point taken to be 0 0 Direction shows the agent s orientation in radians so one revolution 360 degree is 2 Because the calculations are a bit troublesome we will not use this variable here 1 3 4 Adding Output Settings 1 Component placement and settings 2 Output settings 1 12 Agent Based Simulator User s Manual 3
120. trol starting and stopping for simulations The topmost buttons from left to right are Run Step Pause and Stop Click Run to start a simulation Stop to end it or Pause to stop it temporarily Clicking the Step button executes a simulation one step at a time Each click of the button executes one step after while the simulation pause Control Pangi l You can use the two sliders below the buttons to change settings gt 1 Ii re in real time s L Number of Turtles varies the number of turtles shown on the screen from 400 to 600 m e Threshold indicates the personality of the turtles Moving it farther to the right makes the turtles increasingly discriminating 0 3000 0 8000 Let s give it a try In the Control Panel window click the Run button Did a screen like the one shown below appear 3 Results You see three windows appear Happy Turtles Parameters and Two dimensional Space The simulation continues and these windows show the results in real time until you Stop or Agent Based Simulator User s Manual 1 3 Pause or all the turtles finish moving to locations where they are satisfied See for yourself what results this simulation model leads to 1 1 2 Sugarscape Model A Simulation of an Anthill 1 About This Simulation This model simulates two types of ants swarming on a mound of sugar in an islandlike configuration The settings are such that the red ants have a wide field of view
121. ts the value of an expression to Double data type Converts the value of an expression to Integer data type Converts the value of an expression to String data type Beats Converts to False when an expression evaluates to 0 and Boo converts to True otherwise Agent Based Simulator User s Manual 3 13 3 7 4 Agent Functions _CountAgent Returns the number of instances of a specified agent Returns the number of instances of surrounding agents in _ViewCountAgent two dimensional space grid model or hexagon model centered at specified coordinates Returns the number of instances of surrounding agents in _ViewCountAgent2 two dimensional space grid model or hexagon model centered at specified coordinates All mode available Randomly places a specified agent z Seeks and moves to a surrounding unoccupied site centered _MoveToSpace f s on specified coordinates Seeks and moves to a surrounding unoccupied site centered ToCollectionSpace jon specified coordinates not overlapping with agents belonging to a specified collection Seeks and moves to a surrounding site in two dimensional ToRichValue space centered at specified coordinates where the value of a specified variable is largest Advances forward direction of advance is determined by the Forward Direction variable Changes the orientation the Direction variable is modified _CreateAgent Creates an agent _CountCollection Returns the number of objects
122. u select Fixed Sequence execution proceeds in sequence from the top of the tree down 2 26 Agent Based Simulator User s Manual Run Continuously Tab When Initial Values Change Setting Is Set to None Maximum Number of Executions Simulation Setting 7 x The simulation is repeated P Sim Log runtype multi Report the number of times entered unless you quit the Initial Value Change Setting simulation None C Linear C Random Max Repeat fa Times When Initial Values Change Setting is Set to Linear Initial Value Change Variable Simulation Senie E Name Sin Lo runtype multi Report When you want to perform a aE p a simulation with the initial Initial Value Change Setting value of a particular variable sername P C None Linear C Random Rososesceseoossessoos changed in a stepwise manner then enter the variable name here Changing Var For instance if you want to execute a total of 11 types of simulations with the initial Start fo End fu value of a particular variable Range a varied from 0 to 1 in steps of 0 1 ordinarily you would Repeat Number in Same 1 have to redo the setting of the initial value ten times and run a simulation for each one By using this setting however you can make the setting once and perform simulations while varying the initial value automatically until the conditions are fulfilled Agent Based Simulator User s Manual 2 27 St
123. ure that behaviors per unit time are strictly performed you need to modify the rules In this case you can use the backup technique A backup keeps an agent s read information A and write information A separate and the agent temporarily holds the write information in a backup A After execution of all agent rules finishes the results A are written en masse to the original information A gt When agent states must be synchronized in each step use backup variables The variables in this Forest fire model that need to be backed up are the state variables for the agents so create a backup variable called state_B Adding the Agent Variables Under the agent hierarchy create a new Var Property xj variable For Variable Name enter state_B Set Variable Type to Integer and leave Number of Dimensions set at 0 RA Integer Number of fo E 0 th D ArraySize 0 Mer men Changing the World Rule Add the rules for the backup variable to the execution rule for the World agent The initial rule does not change Fire02 abs World rule Agt_Init e o e The initial rule does not change Agt_Step Dim Colas Collection Obj as Object Dimi as Integer Col _CollectAgent World twoDimensionalSpace tree For Each Obj in Col Obj state Obj state_B NextObj This execution rule writes the back up variable to the original variable First all tree agents are stored in the Col variable then the state_
124. ve processing For statement This is used to repeat processing a specific number of times The format is as follows For loop variable start value To end value Step step value When Step value is omitted step defaults to 1 Block statement Next loop variable Example total 0 Fori 1 To 10 Step 1 total total i Nexti Do While statement This is used to repeat processing while an expression evaluates to true The format is as follows Do While expression Block statement Loop 3 10 Agent Based Simulator User s Manual Do Until statement This is used to repeat processing while an expression evaluates to false that is until it evaluates to true Do Until expression Block statement Loop 3 6 7 Jump Statements Jump statements change the flow of control Goto statement This is used to jump to a specified location The format is as follows Goto jump destination label name Jump destination label name Example Do Whilex gt 0 Do while y gt 0 If err_flag True Then Goto error_handling EndIf Loop Loop Jump to specified label Goto normal_processing error_handling Break statement This is used to break out of a loop Example To escape from a While loop Do While conditional expression Do While conditional expression If conditional expression for escape Then Break coe I Escape one level Agent Based Simulator User s Manual 3 11 Example
125. x3 10 20 30 As Double Dim This is a reserved word that indicates the start of variable declaration Variable name This is written using the following format 1 For a simple variable Variable name 2 For an array variable This is declared using the following format Dm variable name I ml mn As variable type variable name2 m1 mn As variable type m1 Number of array elements in the first dimension 1 mn Number of array elements in the nth dimension 1 Agent Based Simulator User s Manual 3 5 There is no particular restriction on the number of dimensions Examples Dim dx 10 As Integer Declares a one dimensional array having 11 elements fromdx 0 todx 10 Dim ds 2 3 As String Declares a two dimensional array having 3 4 elements I ds 0 0 ds 0 1 ds 0 2 ds 0 3 ds 1 0 ds 1 1 ds 1 2 ds 1 3 I ds 2 0 ds 2 1 ds 2 2 ds 2 3 As This is a reserved word indicating that the variable type follows 3 5 2 Variable Type Declaration There are eight variable types Type Name Value range Boolean data type Boolean True or False String data type String 0 to 1 000 characters Integer data type Integer 2 147 483 648 2 147 483 647 when negative aan Double 4 94065645841247 x 10 1 79769313486232 x 10 when positive Agent data type Agent Agent name defined in Tree Object data type Obj
126. yback Window Help Oe tmt Canvas WORLD ey Control Panel WORLD off SPACE _ amp Select New Space S New Agent a New Var In the Output Item List click Close to close the dialog box 1 3 5 Running It A Turtle that Does Nothing At the Control Panel window try clicking Run In Output Item List Close this state the agent still doesn t have any rules so it just sits there and does nothing Now however you ve created the minimum Ll La L gt Lo of elements and state for making the agent move Add Edit Delete around Add to Output Items As At the Control Panel window Click Stop to quit the simulation From the menu bar click File to display the menu then choose Save As Name the program progOl abs and save it 1 14 Agent Based Simulator User s Manual 1 3 6 Opening the Rule Editor 1 Component placement and settings 2 Output settings 3 Describing agent rules 4 Running and debugging The present state isn t very interesting so let s apply some rules to the agent We ll add these rules to progOl abs which you created in the previous section If you are starting again from this section then double click the progO1 abs file you saved to open it In the component tree right click the Turtle agent to display the context menu From the menu select Rule Editor This displays the Rule Editor window for the agent You se

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