ParticleFilterTest.java 

package blog;

import java.util.*;
import java.io.*;
import common.Histogram;
import common.Util;
import common.UnaryPredicate;

import junit.framework.TestCase;
Unit testing for the { Because sampling can potentially fail no matter the error margin, tests sometimes fail. This should be rare, however. If so, the user can check the indicated error to see if things look ok, or run the test again.

Link:  ParticleFilter}. 


public class ParticleFilterTest extends TestCase {

    // Configuration:
    private double delta = 0.05; // the allowed difference between
                                 // expected and computed values

    public static void main(String[] args) throws Exception {
	Util.initRandom(true);
	junit.textui.TestRunner.run(ParticleFilterTest.class);
    }
Sets particle filter properties to default values before every test. 


    public void setUp() {
	setDefaultParticleFilterProperties();
    }

    private void setDefaultParticleFilterProperties() {
	properties = new Properties();
	properties.setProperty("numParticles", "5000");
	properties.setProperty("useDecayedMCMC", "true");
	properties.setProperty("numMoves", "1");
    }

    private static final String weatherModelString =
	"type RainEvent;" +
	"guaranteed RainEvent Rainy, Dry;" +

	"random RainEvent Weather(Timestep);" +
	"random RainEvent RainyRegion();" +

	"RainyRegion ~ TabularCPD[[0.5, 0.5]]();" +

	"Weather(d) " +
	" 	if (d = @0) then ~ TabularCPD[[0.7, 0.3],[0.3, 0.7]](RainyRegion)" +
	"	else ~ TabularCPD[[0.8 , 0.2]," +
	"	                  [0.3, 0.7]," +
	"	                  [0.6 , 0.4]," +
	"	                  [0.2, 0.8]]" +
	"	             (RainyRegion, Weather(Prev(d)));";

    public void test1() throws Exception {
	setModel(weatherModelString);

	assertProb("obs Weather(@0)=Rainy; query Weather(@0);", "Rainy", 1);
	assertProb("obs Weather(@1)=Rainy; query Weather(@1);", "Rainy", 1);
	assertProb("obs Weather(@2)=Rainy; query Weather(@2);", "Rainy", 1);
	assertProb("query Weather(@3);", "Rainy", 0.7611510791366907); // calculated by exact inference
	assertProb("query RainyRegion;", "Rainy", 0.8057553956834532);
    }

    public void test2() throws Exception {
	setModel(weatherModelString);

	assertProb("query Weather(@3);", "Rainy", 0.47185);
	assertProb("query RainyRegion;", "Rainy", 0.5);
    }

    public void testLongerInterval() throws Exception {
	setModel(weatherModelString);

	properties.setProperty("numParticles", "1000");

	assertProb("query Weather(@15);", "Rainy", 0.45);
	assertProb("query RainyRegion;", "Rainy", 0.5);
	
	setDefaultParticleFilterProperties();
    }

    private void setModel(String newModelString) throws Exception {
	model = new Model();
	Main.stringSetup(model, new Evidence(), new LinkedList(), newModelString);
	engine = new ParticleFilter(model, properties);
    }

    private void assertProb(String evidenceAndQuery, String valueString, double expected) throws Exception {
	BLOGParser.ModelEvidenceQueries meq = BLOGParser.parseString(model, evidenceAndQuery);
	engine.take(meq.evidence);
	engine.answer(meq.queries);
	assertEquals(expected, getProbabilityByString(getQuery(meq.queries), valueString), delta);
	outputQueries(meq.queries);
    }

    private void outputQueries(Collection queries) {
	for(Iterator it = queries.iterator(); it.hasNext();) {
	    ArgSpecQuery query = (ArgSpecQuery) it.next();
	    for(Iterator it2 = query.getHistogram().entrySet().iterator(); it2.hasNext();) {
		Histogram.Entry entry = (Histogram.Entry) it2.next();
		double prob = entry.getWeight() / query.getHistogram().getTotalWeight();
		System.out.println("Prob. of " + query + " = " + entry.getElement() + " is " + prob);
	    }
	}
    }
Helper function to get the probability of a value in an answered query from its string. 


    private static double getProbabilityByString(ArgSpecQuery query, String valueString) {
	Histogram hist = query.getHistogram();
	Object value = model.getConstantValue(valueString);
	return hist.getWeight(value) / hist.getTotalWeight();
    }
Helper function that gets a collection assumed to contain a single query and returns that query. 


    private ArgSpecQuery getQuery(Collection singleton) {
	return (ArgSpecQuery ) Util.getFirst(singleton);
    }

    private static Properties properties; 
    private static ParticleFilter engine;
    private static Model model;
}

This file was generated on Tue Jun 08 17:53:36 PDT 2010 from file ParticleFilterTest.java
by the ilog.language.tools.Hilite Java tool written by Hassan Aït-Kaci