question about initializing agents

[Jake Saunders]

Hi

I am trying to initialise and add agents to a netlogo model through the extension api.

This is causing me some issues mostly down to creating the actual agent adding it directly onto the model. i cannot set an agent variable as i cannot initialise it (probably due to my own lack of knowledge).

Can someone please advise me

Kind regards

Jake Saunders 

[Michael Tamillow]

Hi Jake,

I'll try to help you if I can, but I'm little rusty.

I am thinking you could use the 'world' object, it is not in the extension API.

For some applications, you may want more power than the controlling API can provide. In these cases, you need to import from the actual Netlogo packages, rather then org.nlogo.api.

My imports in the Auction module look like this: Auction Github Link

import org.nlogo.agent.World

import org.nlogo.api.ExtensionException

import org.nlogo.{agent, api, core}

import core.Syntax._

import api.ScalaConversions._ // implicits

import scala.collection.mutable.HashMap

As you can see, I am importing from org.nlogo.agent.World

http://ccl.northwestern.edu/netlogo/docs/scaladoc/org/nlogo/agent/World.html

When you look at the documentation for World, you will see a method called createTurtle. I believe this is the method you need. After you create the turtle you can modify the attributes associated with each agent so that the agent is in the proper location with the proper internal states. You can even getOrCreateTurtle if you have clear expectations of what you want.

You can see that even though the nlogo.api has a lot of power, if you want unlimited power (and I, for one, do!) you can drill down to actual netlogo code. At one point I needed this line:

val turt = turtle.asInstanceOf[agent.Turtle]

because there is a method in the nlogo.agent.Turtle object that is not in the  nlogo.api.Turtle. Try that, let me know how it works.

Hope that helps,

Mike

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[Jake Saunders]

Hi

Thank you for your help 

I have since been able to create the turtles using this method the real problem is:

I cant create them to be different breeds without getting a invalid breed error. the breed is already initialised within the netlogo code but for some reason doesn't work. Any insights ?

Here is the code:

Java 

World world = (World) cntx.getAgent().world();

AgentSet breed = world.getBreed("males");

Turtle t = world.createTurtle(breed);

Netlogo 

extensions [epiInput];

Breed [males male];

Breed [females female ];

males-own [

  age

]

Error 

java.lang.IllegalArgumentException: invalid breed

 at org.nlogo.agent.TurtleManagement.getVariablesArraySize(TurtleManagement.scala:122)

 at org.nlogo.agent.TurtleManagement.getVariablesArraySize$(TurtleManagement.scala:118)

 at org.nlogo.agent.World.getVariablesArraySize(World.scala:109)

 at org.nlogo.agent.Turtle.<init>(Turtle.java:87)

 at org.nlogo.agent.Turtle2D.<init>(Turtle2D.java:12)

 at org.nlogo.agent.World2D.createTurtle(World.scala:225)

 at demographicInput.createAgents(demographicInput.java:182)

 at demographicInput.report(demographicInput.java:67)

 at org.nlogo.prim._externreport.report(_externreport.java:31)

 at org.nlogo.prim._asm_procedurego_setprocedurevariable_5.perform()

 at org.nlogo.nvm.Context.stepConcurrent(Context.java:107)

 at org.nlogo.nvm.ConcurrentJob.step(ConcurrentJob.scala:65)

 at org.nlogo.job.JobThread.runPrimaryJobs(JobThread.scala:133)

 at org.nlogo.job.JobThread.$anonfun$run$1(JobThread.scala:68)

 at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)

 at scala.util.control.Exception$Catch.apply(Exception.scala:224)

 at org.nlogo.api.Exceptions$.handling(Exceptions.scala:41)

 at org.nlogo.job.JobThread.run(JobThread.scala:66)

Kind regards

Jake 

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[Michael Tamillow]

Line 118 of TurtleManagement.scala:

  def getVariablesArraySize(turtle: org.nlogo.api.Turtle, breed: org.nlogo.api.AgentSet): Int = {

    if (breed == _turtles) {

      program.turtlesOwn.size

    } else {

      if (breed == null) throw new IllegalArgumentException("invalid breed")

      val breedOwns = program.breeds(breed.printName).owns

      program.turtlesOwn.size + breedOwns.size

    }

  }

}

So, that means your line 

AgentSet breed = world.getBreed("males");

is returning null.

Perhaps the lines in your Java program are being executed before the Netlogo program even starts, which would mean the environment in Netlogo is not initialized with the breeds.

My advice would be localize the Java code in such a way that you can guarantee that it will never execute before the breeds are initialized.

Let me know what you find,

Mike

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