com.anhth12.distributions.Distributions.java Source code

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Here is the source code for com.anhth12.distributions.Distributions.java

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package com.anhth12.distributions;

import org.apache.commons.math3.distribution.ExponentialDistribution;
import org.apache.commons.math3.distribution.NormalDistribution;
import org.apache.commons.math3.distribution.RealDistribution;
import org.apache.commons.math3.distribution.UniformRealDistribution;
import org.apache.commons.math3.random.RandomGenerator;
import org.canova.api.util.MultiDimensionalMap;

/**
 *
 * @author anhth12
 */
public class Distributions {

    private static final MultiDimensionalMap<RandomGenerator, Double, RealDistribution> normalDistributions = MultiDimensionalMap
            .newHashBackedMap();
    private static final MultiDimensionalMap<RandomGenerator, Double, RealDistribution> exponentialDist = MultiDimensionalMap
            .newHashBackedMap();
    private static final MultiDimensionalMap<RandomGenerator, Double, RealDistribution> uniformDist = MultiDimensionalMap
            .newHashBackedMap();

    public static RealDistribution exponential(RandomGenerator rng, double mean) {
        if (exponentialDist.get(rng, mean) == null) {
            RealDistribution ret = new ExponentialDistribution(rng, 1.0,
                    ExponentialDistribution.DEFAULT_INVERSE_ABSOLUTE_ACCURACY);
            exponentialDist.put(rng, mean, ret);
        }
        return exponentialDist.get(rng, mean);
    }

    public static RealDistribution normal(RandomGenerator rng, double std) {
        if (normalDistributions.get(rng, std) == null) {
            RealDistribution ret = new NormalDistribution(rng, 0, std,
                    NormalDistribution.DEFAULT_INVERSE_ABSOLUTE_ACCURACY);
            normalDistributions.put(rng, std, ret);
            return ret;
        }
        return normalDistributions.get(rng, std);
    }

    public static RealDistribution uniform(RandomGenerator rng, double fanIn) {
        fanIn = Math.abs(fanIn);
        if (uniformDist.get(rng, fanIn) == null) {
            RealDistribution ret = new UniformRealDistribution(rng, -fanIn, fanIn);
            uniformDist.put(rng, fanIn, ret);
            return ret;
        }

        return uniformDist.get(rng, fanIn);
    }

    public static RealDistribution uniform(RandomGenerator rng, double min, double max) {
        return new UniformRealDistribution(rng, min, max);
    }

    public static RealDistribution uniform(RandomGenerator rng, int nIn, int nOut) {
        double fanIn = -4 * Math.sqrt(6. / (nOut + nIn));
        return uniform(rng, fanIn);
    }

    public static RealDistribution uniform(RandomGenerator rng) {
        double fanIn = 0.1;
        return new UniformRealDistribution(rng, -fanIn, fanIn);
    }
}