org.jpmml.evaluator.DistributionUtil.java Source code

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Here is the source code for org.jpmml.evaluator.DistributionUtil.java

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/*
 * Copyright (c) 2015 Villu Ruusmann
 *
 * This file is part of JPMML-Evaluator
 *
 * JPMML-Evaluator is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * JPMML-Evaluator is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with JPMML-Evaluator.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.jpmml.evaluator;

import org.apache.commons.math3.distribution.NormalDistribution;
import org.dmg.pmml.ContinuousDistribution;
import org.dmg.pmml.DataType;
import org.dmg.pmml.GaussianDistribution;
import org.dmg.pmml.PoissonDistribution;

public class DistributionUtil {

    private DistributionUtil() {
    }

    /**
     * <p>
     * Calculates the value of the specified probability function at the specified point.
     * </p>
     */
    static public double probability(ContinuousDistribution distribution, Number x) {

        if (distribution instanceof GaussianDistribution) {
            return probability((GaussianDistribution) distribution, x);
        } else

        if (distribution instanceof PoissonDistribution) {
            return probability((PoissonDistribution) distribution, x);
        }

        throw new UnsupportedFeatureException(distribution);
    }

    static public double probability(GaussianDistribution gaussianDistribution, Number x) {
        NormalDistribution distribution = new NormalDistribution(gaussianDistribution.getMean(),
                Math.sqrt(gaussianDistribution.getVariance()));

        return distribution.density(x.doubleValue());
    }

    static public double probability(PoissonDistribution poissonDistribution, Number x) {
        org.apache.commons.math3.distribution.PoissonDistribution distribution = new org.apache.commons.math3.distribution.PoissonDistribution(
                null, poissonDistribution.getMean(),
                org.apache.commons.math3.distribution.PoissonDistribution.DEFAULT_EPSILON,
                org.apache.commons.math3.distribution.PoissonDistribution.DEFAULT_MAX_ITERATIONS);

        x = (Number) TypeUtil.cast(DataType.INTEGER, x);

        return distribution.probability(x.intValue());
    }

    static public boolean isNoOp(ContinuousDistribution distribution) {

        if (distribution instanceof GaussianDistribution) {
            return isNoOp((GaussianDistribution) distribution);
        }

        return true;
    }

    static public boolean isNoOp(GaussianDistribution gaussianDistribution) {
        return (gaussianDistribution.getVariance() <= 0d);
    }
}