Re: [Swarm-Support] want to see example of generating random values

[Steve Railsback]

Tieju MA wrote:
> I want to generate random values following LogNormal distributions with 
> specified mean and variance, but I am very much confused about 
> LogNormalDistCImpl 
> <http://www.swarm.org/swarmdocs-2.2/refbook-java/swarm/random/LogNormalDistCImpl.html> 
>
> LogNormalDistImpl 
> <http://www.swarm.org/swarmdocs-2.2/refbook-java/swarm/random/LogNormalDistImpl.html>  
> and those interfaces they implement. I don't know how to write the Java 
> code.
> So it will be really appreciate if someone could show me an example of 
> using those classes and interfaces to generate random values.

There is an example use of the *normal* (not LogNormal) distribution in 
the "StupidModel" template code: 
http://www.swarm.org/wiki/Software_templates

Here are code pieces, which were in the Model Swarm.

---
import swarm.random.NormalDistImpl;

---

public class StupidModelSwarm extends SwarmImpl {

        // Declarations
        public ListImpl bugList;
        ...
        private NormalDistImpl bugInitSizeDist;

        // Declare model parameters
        public int numberOfInitialBugs = 100;
        public double initialBugSizeMean = 0.1;
        public double initialBugSizeSD = 0.03;

---
        
// For version 14, we create a normal distribution for
// initial bug sizes here, and use it in getBugInitSize
// This must be created before we create the bugs!
        bugInitSizeDist = new NormalDistImpl
        (this, Globals.env.randomGenerator, initialBugSizeMean, 
initialBugSizeSD);

---

        public double getBugInitSize() {
                // In version 14, initial bug sizes are pulled randomly
                double initBugSize = bugInitSizeDist.getDoubleSample();
                if (initBugSize > 0.0) return initBugSize;
                else return 0.0;
        }


--
Steve Railsback
Lang, Railsback & Associates
Arcata, California
www.LangRailsback.com