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Java example source code file (AbstractIntegerDistributionTest.java)

This example Java source code file (AbstractIntegerDistributionTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractintegerdistributiontest, dicedistribution, test

The AbstractIntegerDistributionTest.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math3.distribution;

import org.junit.Assert;
import org.junit.Test;

/**
 * Test cases for AbstractIntegerDistribution default implementations.
 *
 */
public class AbstractIntegerDistributionTest {
    protected final DiceDistribution diceDistribution = new DiceDistribution();
    protected final double p = diceDistribution.probability(1);

    @Test
    public void testInverseCumulativeProbabilityMethod()
    {
        double precision = 0.000000000000001;
        Assert.assertEquals(1, diceDistribution.inverseCumulativeProbability(0));
        Assert.assertEquals(1, diceDistribution.inverseCumulativeProbability((1d-Double.MIN_VALUE)/6d));
        Assert.assertEquals(2, diceDistribution.inverseCumulativeProbability((1d+precision)/6d));
        Assert.assertEquals(2, diceDistribution.inverseCumulativeProbability((2d-Double.MIN_VALUE)/6d));
        Assert.assertEquals(3, diceDistribution.inverseCumulativeProbability((2d+precision)/6d));
        Assert.assertEquals(3, diceDistribution.inverseCumulativeProbability((3d-Double.MIN_VALUE)/6d));
        Assert.assertEquals(4, diceDistribution.inverseCumulativeProbability((3d+precision)/6d));
        Assert.assertEquals(4, diceDistribution.inverseCumulativeProbability((4d-Double.MIN_VALUE)/6d));
        Assert.assertEquals(5, diceDistribution.inverseCumulativeProbability((4d+precision)/6d));
        Assert.assertEquals(5, diceDistribution.inverseCumulativeProbability((5d-precision)/6d));//Can't use Double.MIN
        Assert.assertEquals(6, diceDistribution.inverseCumulativeProbability((5d+precision)/6d));
        Assert.assertEquals(6, diceDistribution.inverseCumulativeProbability((6d-precision)/6d));//Can't use Double.MIN
        Assert.assertEquals(6, diceDistribution.inverseCumulativeProbability((6d)/6d));
    }

    @Test
    public void testCumulativeProbabilitiesSingleArguments() {
        for (int i = 1; i < 7; i++) {
            Assert.assertEquals(p * i,
                    diceDistribution.cumulativeProbability(i), Double.MIN_VALUE);
        }
        Assert.assertEquals(0.0,
                diceDistribution.cumulativeProbability(0), Double.MIN_VALUE);
        Assert.assertEquals(1.0,
                diceDistribution.cumulativeProbability(7), Double.MIN_VALUE);
    }

    @Test
    public void testCumulativeProbabilitiesRangeArguments() {
        int lower = 0;
        int upper = 6;
        for (int i = 0; i < 2; i++) {
            // cum(0,6) = p(0 < X <= 6) = 1, cum(1,5) = 4/6, cum(2,4) = 2/6
            Assert.assertEquals(1 - p * 2 * i,
                    diceDistribution.cumulativeProbability(lower, upper), 1E-12);
            lower++;
            upper--;
        }
        for (int i = 0; i < 6; i++) {
            Assert.assertEquals(p, diceDistribution.cumulativeProbability(i, i+1), 1E-12);
        }
    }

    /**
     * Simple distribution modeling a 6-sided die
     */
    class DiceDistribution extends AbstractIntegerDistribution {
        public static final long serialVersionUID = 23734213;

        private final double p = 1d/6d;

        public DiceDistribution() {
            super(null);
        }

        public double probability(int x) {
            if (x < 1 || x > 6) {
                return 0;
            } else {
                return p;
            }
        }

        public double cumulativeProbability(int x) {
            if (x < 1) {
                return 0;
            } else if (x >= 6) {
                return 1;
            } else {
                return p * x;
            }
        }

        public double getNumericalMean() {
            return 3.5;
        }

        public double getNumericalVariance() {
            return 70/24;  // E(X^2) - E(X)^2
        }

        public int getSupportLowerBound() {
            return 1;
        }

        public int getSupportUpperBound() {
            return 6;
        }

        public final boolean isSupportConnected() {
            return true;
        }
    }
}

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