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Java example source code file (StorelessUnivariateStatisticAbstractTest.java)

This example Java source code file (StorelessUnivariateStatisticAbstractTest.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

override, secondmoment, storelessunivariatestatistic, storelessunivariatestatisticabstracttest, test, univariatestatistic

The StorelessUnivariateStatisticAbstractTest.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.stat.descriptive;

import org.apache.commons.math3.TestUtils;
import org.apache.commons.math3.stat.descriptive.moment.SecondMoment;
import org.apache.commons.math3.util.FastMath;
import org.junit.Assert;
import org.junit.Test;

/**
 * Test cases for {@link StorelessUnivariateStatistic} classes.
 */
public abstract class StorelessUnivariateStatisticAbstractTest
    extends UnivariateStatisticAbstractTest {

    /** Small sample arrays */
    protected double[][] smallSamples = {{}, {1}, {1,2}, {1,2,3}, {1,2,3,4}};

    /** Return a new instance of the statistic */
    @Override
    public abstract UnivariateStatistic getUnivariateStatistic();

    /**Expected value for  the testArray defined in UnivariateStatisticAbstractTest */
    @Override
    public abstract double expectedValue();

    /**
     *  Verifies that increment() and incrementAll work properly.
     */
    @Test
    public void testIncrementation() {

        StorelessUnivariateStatistic statistic =
            (StorelessUnivariateStatistic) getUnivariateStatistic();

        // Add testArray one value at a time and check result
        for (int i = 0; i < testArray.length; i++) {
            statistic.increment(testArray[i]);
        }

        Assert.assertEquals(expectedValue(), statistic.getResult(), getTolerance());
        Assert.assertEquals(testArray.length, statistic.getN());

        statistic.clear();

        // Add testArray all at once and check again
        statistic.incrementAll(testArray);
        Assert.assertEquals(expectedValue(), statistic.getResult(), getTolerance());
        Assert.assertEquals(testArray.length, statistic.getN());

        statistic.clear();

        // Cleared
        checkClearValue(statistic);
        Assert.assertEquals(0, statistic.getN());

    }

    protected void checkClearValue(StorelessUnivariateStatistic statistic){
        Assert.assertTrue(Double.isNaN(statistic.getResult()));
    }

    @Test
    public void testSerialization() {

        StorelessUnivariateStatistic statistic =
            (StorelessUnivariateStatistic) getUnivariateStatistic();

        TestUtils.checkSerializedEquality(statistic);

        statistic.clear();

        for (int i = 0; i < testArray.length; i++) {
            statistic.increment(testArray[i]);
            if(i % 5 == 0)
                statistic = (StorelessUnivariateStatistic)TestUtils.serializeAndRecover(statistic);
        }

        TestUtils.checkSerializedEquality(statistic);

        Assert.assertEquals(expectedValue(), statistic.getResult(), getTolerance());

        statistic.clear();

        checkClearValue(statistic);

    }

    @Test
    public void testEqualsAndHashCode() {
        StorelessUnivariateStatistic statistic =
            (StorelessUnivariateStatistic) getUnivariateStatistic();
        StorelessUnivariateStatistic statistic2 = null;

        Assert.assertTrue("non-null, compared to null", !statistic.equals(statistic2));
        Assert.assertTrue("reflexive, non-null", statistic.equals(statistic));

        int emptyHash = statistic.hashCode();
        statistic2 = (StorelessUnivariateStatistic) getUnivariateStatistic();
        Assert.assertTrue("empty stats should be equal", statistic.equals(statistic2));
        Assert.assertEquals("empty stats should have the same hashcode",
                emptyHash, statistic2.hashCode());

        statistic.increment(1d);
        Assert.assertTrue("reflexive, non-empty", statistic.equals(statistic));
        Assert.assertTrue("non-empty, compared to empty", !statistic.equals(statistic2));
        Assert.assertTrue("non-empty, compared to empty", !statistic2.equals(statistic));
        Assert.assertTrue("non-empty stat should have different hashcode from empty stat",
                statistic.hashCode() != emptyHash);

        statistic2.increment(1d);
        Assert.assertTrue("stats with same data should be equal", statistic.equals(statistic2));
        Assert.assertEquals("stats with same data should have the same hashcode",
                statistic.hashCode(), statistic2.hashCode());

        statistic.increment(Double.POSITIVE_INFINITY);
        Assert.assertTrue("stats with different n's should not be equal", !statistic2.equals(statistic));
        Assert.assertTrue("stats with different n's should have different hashcodes",
                statistic.hashCode() != statistic2.hashCode());

        statistic2.increment(Double.POSITIVE_INFINITY);
        Assert.assertTrue("stats with same data should be equal", statistic.equals(statistic2));
        Assert.assertEquals("stats with same data should have the same hashcode",
                statistic.hashCode(), statistic2.hashCode());

        statistic.clear();
        statistic2.clear();
        Assert.assertTrue("cleared stats should be equal", statistic.equals(statistic2));
        Assert.assertEquals("cleared stats should have thashcode of empty stat",
                emptyHash, statistic2.hashCode());
        Assert.assertEquals("cleared stats should have thashcode of empty stat",
                emptyHash, statistic.hashCode());

    }

    @Test
    public void testMomentSmallSamples() {
        UnivariateStatistic stat = getUnivariateStatistic();
        if (stat instanceof SecondMoment) {
            SecondMoment moment = (SecondMoment) getUnivariateStatistic();
            Assert.assertTrue(Double.isNaN(moment.getResult()));
            moment.increment(1d);
            Assert.assertEquals(0d, moment.getResult(), 0);
        }
    }

    /**
     * Make sure that evaluate(double[]) and inrementAll(double[]),
     * getResult() give same results.
     */
    @Test
    public void testConsistency() {
        StorelessUnivariateStatistic stat = (StorelessUnivariateStatistic) getUnivariateStatistic();
        stat.incrementAll(testArray);
        Assert.assertEquals(stat.getResult(), stat.evaluate(testArray), getTolerance());
        for (int i = 0; i < smallSamples.length; i++) {
            stat.clear();
            for (int j =0; j < smallSamples[i].length; j++) {
                stat.increment(smallSamples[i][j]);
            }
            TestUtils.assertEquals(stat.getResult(), stat.evaluate(smallSamples[i]), getTolerance());
        }
    }

    /**
     * Verifies that copied statistics remain equal to originals when
     * incremented the same way.
     *
     */
    @Test
    public void testCopyConsistency() {

        StorelessUnivariateStatistic master =
            (StorelessUnivariateStatistic) getUnivariateStatistic();

        StorelessUnivariateStatistic replica = null;

        // Randomly select a portion of testArray to load first
        long index = FastMath.round((FastMath.random()) * testArray.length);

        // Put first half in master and copy master to replica
        master.incrementAll(testArray, 0, (int) index);
        replica = master.copy();

        // Check same
        Assert.assertTrue(replica.equals(master));
        Assert.assertTrue(master.equals(replica));

        // Now add second part to both and check again
        master.incrementAll(testArray,
                (int) index, (int) (testArray.length - index));
        replica.incrementAll(testArray,
                (int) index, (int) (testArray.length - index));
        Assert.assertTrue(replica.equals(master));
        Assert.assertTrue(master.equals(replica));
    }

    @Test
    public void testSerial() {
        StorelessUnivariateStatistic s =
            (StorelessUnivariateStatistic) getUnivariateStatistic();
        Assert.assertEquals(s, TestUtils.serializeAndRecover(s));
    }
}

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