A RePast Tutorial by John T. Murphy, University of Arizona & Arizona State University (contact)

Creating the agents

The model object will create the specified number of instances of the agent objects to begin the simulation. This will require a number of elements:

1. A list of the agents. This will be a special Java object called an ArrayList.
2. A routine that creates n agents and adds them to this list.
3. A statement that destroys the list of agents when the 'setup' function tears down the model.

For now we will create the agents and add them to the Agent list. We will create a separate method of the model object that does this, which we will make more elaborate in the next step.

CarryDropModel

// CarryDropModel
package demo;

import java.awt.Color;
import java.util.ArrayList;

import uchicago.src.sim.engine.Schedule;
import uchicago.src.sim.engine.SimInit;
import uchicago.src.sim.engine.SimModelImpl;
import uchicago.src.sim.gui.DisplaySurface;
import uchicago.src.sim.gui.ColorMap;
import uchicago.src.sim.gui.Value2DDisplay;

public class CarryDropModel extends SimModelImpl {
  // Default Values
  private static final int NUMAGENTS = 100;
  private static final int WORLDXSIZE = 40;
  private static final int WORLDYSIZE = 40;
  private static final int TOTALMONEY = 1000;
  private static final int AGENT_MIN_LIFESPAN = 30;
  private static final int AGENT_MAX_LIFESPAN = 50;

  private int numAgents = NUMAGENTS;
  private int worldXSize = WORLDXSIZE;
  private int worldYSize = WORLDYSIZE;
  private int money = TOTALMONEY;
  private int agentMinLifespan = AGENT_MIN_LIFESPAN;
  private int agentMaxLifespan = AGENT_MAX_LIFESPAN;

  private Schedule schedule;

  private CarryDropSpace cdSpace;

  private ArrayList agentList;

  private DisplaySurface displaySurf;

  public String getName(){
    return "Carry And Drop";
  }

  public void setup(){
    System.out.println("Running setup");
    cdSpace = null;
    agentList = new ArrayList();

    if (displaySurf != null){
      displaySurf.dispose();
    }
    displaySurf = null;

    displaySurf = new DisplaySurface(this, "Carry Drop Model Window 1");

    registerDisplaySurface("Carry Drop Model Window 1", displaySurf);
  }

  public void begin(){
    buildModel();
    buildSchedule();
    buildDisplay();

    displaySurf.display();
  }

  public void buildModel(){
    System.out.println("Running BuildModel");
    cdSpace = new CarryDropSpace(worldXSize, worldYSize);
    cdSpace.spreadMoney(money);

    for(int i = 0; i < numAgents; i++){
      addNewAgent();
    }
  }

  public void buildSchedule(){
    System.out.println("Running BuildSchedule");
  }

  public void buildDisplay(){
    System.out.println("Running BuildDisplay");

    ColorMap map = new ColorMap();

    for(int i = 1; i<16; i++){
      map.mapColor(i, new Color((int)(i * 8 + 127), 0, 0));
    }
    map.mapColor(0, Color.white);

    Value2DDisplay displayMoney =
        new Value2DDisplay(cdSpace.getCurrentMoneySpace(), map);

    displaySurf.addDisplayable(displayMoney, "Money");

  }

  private void addNewAgent(){
    CarryDropAgent a = new CarryDropAgent(agentMinLifespan, agentMaxLifespan);
    agentList.add(a);
  }

  public Schedule getSchedule(){
    return schedule;
  }

  public String[] getInitParam(){
    String[] initParams = { "NumAgents", "WorldXSize", "WorldYSize", "Money", "AgentMinLifespan", "AgentMaxLifespan"};
    return initParams;
  }

  public int getNumAgents(){
    return numAgents;
  }

  public void setNumAgents(int na){
    numAgents = na;
  }

  public int getWorldXSize(){
    return worldXSize;
  }

  public void setWorldXSize(int wxs){
    worldXSize = wxs;
  }

  public int getWorldYSize(){
    return worldYSize;
  }

  public void setWorldYSize(int wys){
    worldYSize = wys;
  }

  public int getMoney() {
    return money;
  }

  public void setMoney(int i) {
    money = i;
  }

  public int getAgentMaxLifespan() {
    return agentMaxLifespan;
  }

  public int getAgentMinLifespan() {
    return agentMinLifespan;
  }

  public void setAgentMaxLifespan(int i) {
    agentMaxLifespan = i;
  }

  public void setAgentMinLifespan(int i) {
    agentMinLifespan = i;
  }

  public static void main(String[] args) {
    SimInit init = new SimInit();
    CarryDropModel model = new CarryDropModel();
    init.loadModel(model, "", false);
  }

}

CarryDropAgent

// CarryDropAgent
package demo;

public class CarryDropAgent {
  private int x;
  private int y;
  private int money;
  private int stepsToLive;

  public CarryDropAgent(int minLifespan, int maxLifespan){
    x = -1;
    y = -1;
    money = 0;
    stepsToLive =
        (int)((Math.random() * (maxLifespan - minLifespan)) + minLifespan);
  }

}

CarryDropSpace

// CarryDropSpace
package demo;

import uchicago.src.sim.space.Object2DGrid;


public class CarryDropSpace {
private Object2DGrid moneySpace;

  public CarryDropSpace(int xSize, int ySize){
    moneySpace = new Object2DGrid(xSize, ySize);

    for(int i = 0; i < xSize; i++){
      for(int j = 0; j < ySize; j++){
        moneySpace.putObjectAt(i,j,new Integer(0));
      }
    }
  }

  public void spreadMoney(int money){
    // Randomly place money in moneySpace
    for(int i = 0; i < money; i++){

      // Choose coordinates
      int x = (int)(Math.random()*(moneySpace.getSizeX()));
      int y = (int)(Math.random()*(moneySpace.getSizeY()));

      // Get the value of the object at those coordinates
      int currentValue = getMoneyAt(x, y);
      // Replace the Integer object with another one with the new value
      moneySpace.putObjectAt(x,y,new Integer(currentValue + 1));
    }
  }

  public int getMoneyAt(int x, int y){
    int i;
    if(moneySpace.getObjectAt(x,y)!= null){
      i = ((Integer)moneySpace.getObjectAt(x,y)).intValue();
    }
    else{
      i = 0;
    }
    return i;
  }

  public Object2DGrid getCurrentMoneySpace(){
    return moneySpace;
  }

}

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A RePast Tutorial by John T. Murphy, University of Arizona & Arizona State University (contact)