Re: [Swarm-Support] (no subject)

[LRA]

mariem siala wrote:
> Hi !
> We can build agents in Model or Observer.
> But How an agent can create another agent? Have you an example?

Hello,

Yes, agents can create new agents. You can program agents to call their 
own "create" or constructor methods to reproduce.

There is one tricky part: You cannot add (or remove) agents from the 
model's list of agents while the model's schedule is acting on that 
list. (If the model is going through its list of all the StupidBugs and 
telling them each to "grow", by using "createActionForEach", the bugs 
cannot add new bugs to that list until the createActionForEach has 
finished.)

Instead, new agents are usually put on a list of new agents. The model 
then must have a scheduled action that takes the new agents off that 
list and put them on the master agent list.

Do you want an example in Objective-C or Java Swarm?

Steve Railsback

public class StupidBug {

...
        public void grow() {
                HabitatCell myCell = 
(HabitatCell)myCellWorld.getObjectAtX$Y(myX,myY);
                double cellFoodAvailable = myCell.getCellFoodAvailable();
		double foodEaten = Math.min(cellFoodAvailable, 
modelSwarm.getBugMaxConsumptionRate());
                myCell.setCellFoodAvailable(cellFoodAvailable - foodEaten);
                mySize += foodEaten;
                
                // For version 12, add reproduction to the grow method
                // When we create offspring, we use a new StupidBug constructor 
method
                // New bugs can die during their creation (if they do not find
                // a vacant cell) so we need to be careful ordering cleanup
                // of bug lists in the model swarm
                if (mySize >= 10.0) {
                        // First make 5 more bugs
                        StupidBug newBug;
                        for (int i = 1; i <= 5; i++) {
                                newBug = new StupidBug (myBugWorld, 
myCellWorld, modelSwarm, myX, myY);
                                modelSwarm.add(newBug);
                        }
                        
                        // Then die
                        myBugWorld.putObject$atX$Y(null, myX, myY);
                        modelSwarm.remove(this);
                }
                return;
        }

...

        // Here is the new constructor method used for reproduction
	public StupidBug (Grid2dImpl aBugSpace, Grid2dImpl aCellSpace, 
StupidModelSwarm aModelSwarm, int momsX, int momsY) {
                myBugWorld = aBugSpace;
                myCellWorld = aCellSpace;
                modelSwarm = aModelSwarm;
                mySize = 0.0;
                neighborCellList = new ListImpl(modelSwarm);
                
                int testX, testY, testCellX, testCellY;
                int moveDistance = 3;
                HabitatCell newCell;
                
                // To find a new location, make a list of available cells
                // This approach is copied from "move"
                neighborCellList.removeAll();
		for (testX = momsX - moveDistance; testX <= momsX + moveDistance; 
testX++) {
			for (testY = momsY - moveDistance; testY <= momsY + moveDistance; 
testY++) {
                                // check the coordinates because Swarm does not
                                // provide a toroidal space
                                testCellX = xnorm(testX);
                                testCellY = ynorm(testY);
                                
                                // If there is no bug at this location, put the 
cell
                                // at the location on the neighbor list.
                                if (myBugWorld.getObjectAtX$Y(testCellX, 
testCellY) == null)
					neighborCellList.addLast(myCellWorld.getObjectAtX$Y(testCellX, 
testCellY));
                        }
                }
                // If no vacant neighbor cells were found, the new bug dies
                if (neighborCellList.getCount() == 0) {
                        modelSwarm.remove(this);
                        return;
                }
                // Else the new bug moves to a randomly chosen vacant cell
                else {
                        newCell = (HabitatCell) neighborCellList.atOffset
                                
(Globals.env.uniformIntRand.getIntegerWithMin$withMax
                                        (0, neighborCellList.getCount()-1));
                        
                        myX = newCell.getMyX();
                        myY = newCell.getMyY();
                        myBugWorld.putObject$atX$Y(this, myX, myY);
                        // the new bug gets put on the bug list in 'grow'
                }
                return;
        }


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Arcata CA  95521
(707) 822-0453