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WeightedDirichlet.java
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WeightedDirichlet.java
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package lphy.base.distribution;
import lphy.base.math.MathUtils;
import lphy.core.model.RandomVariable;
import lphy.core.model.Value;
import lphy.core.model.annotation.GeneratorCategory;
import lphy.core.model.annotation.GeneratorInfo;
import lphy.core.model.annotation.ParameterInfo;
import org.apache.commons.math3.random.RandomGenerator;
import java.util.Map;
import java.util.TreeMap;
import static lphy.base.distribution.DistributionConstants.concParamName;
/**
* The scaled dirichlet probability distribution.
* @see Dirichlet
* @author Alexei Drummond
* @author Walter Xie
*/
public class WeightedDirichlet extends ParametricDistribution<Double[]> {
public static final String weightsParamName = "weights";
private Value<Number[]> concentration;
private Value<Integer[]> weights;
public WeightedDirichlet(@ParameterInfo(name = concParamName, narrativeName = "concentration", description = "the concentration parameters of the scaled Dirichlet distribution.") Value<Number[]> concentration,
@ParameterInfo(name = weightsParamName, description = "the weight parameters of the scaled Dirichlet distribution.") Value<Integer[]> weights) {
super();
this.concentration = concentration;
this.weights = weights;
}
@Override
protected void constructDistribution(RandomGenerator random) { }
@GeneratorInfo(name = "WeightedDirichlet",
category = GeneratorCategory.PRIOR, examples = {"totalEvidence.lphy","weightedDirichlet.lphy"},
description = "The scaled dirichlet probability distribution.")
public RandomVariable<Double[]> sample() {
Number[] weight = weights.value();
Number[] conc = concentration.value();
double weightsum = 0.0;
for (int i = 0; i < weight.length; i++) {
weightsum += weight[i].doubleValue();
}
Double[] z = new Double[concentration.value().length];
double sum = 0.0;
for (int i = 0; i < z.length; i++) {
double val = MathUtils.randomGamma(conc[i].doubleValue(), 1.0, random);
z[i] = val;
sum += val * (weight[i].doubleValue() / weightsum);
}
for (int i = 0; i < z.length; i++) {
z[i] /= sum;
}
return new RandomVariable<>(null, z, this);
}
public double density(Double d) {
// TODO
return 0;
}
@Override
public Map<String, Value> getParams() {
return new TreeMap<>() {{
put(concParamName, concentration);
put(weightsParamName, weights);
}};
}
@Override
public void setParam(String paramName, Value value) {
if (paramName.equals(concParamName)) concentration = value;
else if (paramName.equals(weightsParamName)) weights = value;
else throw new RuntimeException("Unrecognised parameter name: " + paramName);
super.setParam(paramName, value); // constructDistribution
}
public Value<Number[]> getConcentration() {
return concentration;
}
public Value<Integer[]> getWeights() {
return weights;
}
}