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Java example source code file (SummaryStatisticsTest.java)

This example Java source code file (SummaryStatisticsTest.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

deviation, expecting, geometricmean, illegalstateexception, mean, nan, standard, statisticalsummary, std, string, sum, summarystatistics, test, variance

The SummaryStatisticsTest.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.GeometricMean;
import org.apache.commons.math3.stat.descriptive.moment.Mean;
import org.apache.commons.math3.stat.descriptive.moment.Variance;
import org.apache.commons.math3.stat.descriptive.summary.Sum;
import org.apache.commons.math3.util.FastMath;
import org.junit.Assert;
import org.junit.Test;
/**
 * Test cases for the {@link SummaryStatistics} class.
 */
public class SummaryStatisticsTest {

    private double one = 1;
    private float twoF = 2;
    private long twoL = 2;
    private int three = 3;
    private double mean = 2;
    private double sumSq = 18;
    private double sum = 8;
    private double var = 0.666666666666666666667;
    private double popVar = 0.5;
    private double std = FastMath.sqrt(var);
    private double n = 4;
    private double min = 1;
    private double max = 3;
    private double tolerance = 10E-15;

    protected SummaryStatistics createSummaryStatistics() {
        return new SummaryStatistics();
    }

    /** test stats */
    @Test
    public void testStats() {
        SummaryStatistics u = createSummaryStatistics();
        Assert.assertEquals("total count",0,u.getN(),tolerance);
        u.addValue(one);
        u.addValue(twoF);
        u.addValue(twoL);
        u.addValue(three);
        Assert.assertEquals("N",n,u.getN(),tolerance);
        Assert.assertEquals("sum",sum,u.getSum(),tolerance);
        Assert.assertEquals("sumsq",sumSq,u.getSumsq(),tolerance);
        Assert.assertEquals("var",var,u.getVariance(),tolerance);
        Assert.assertEquals("population var",popVar,u.getPopulationVariance(),tolerance);
        Assert.assertEquals("std",std,u.getStandardDeviation(),tolerance);
        Assert.assertEquals("mean",mean,u.getMean(),tolerance);
        Assert.assertEquals("min",min,u.getMin(),tolerance);
        Assert.assertEquals("max",max,u.getMax(),tolerance);
        u.clear();
        Assert.assertEquals("total count",0,u.getN(),tolerance);
    }

    @Test
    public void testN0andN1Conditions() {
        SummaryStatistics u = createSummaryStatistics();
        Assert.assertTrue("Mean of n = 0 set should be NaN",
                Double.isNaN( u.getMean() ) );
        Assert.assertTrue("Standard Deviation of n = 0 set should be NaN",
                Double.isNaN( u.getStandardDeviation() ) );
        Assert.assertTrue("Variance of n = 0 set should be NaN",
                Double.isNaN(u.getVariance() ) );

        /* n=1 */
        u.addValue(one);
        Assert.assertTrue("mean should be one (n = 1)",
                u.getMean() == one);
        Assert.assertTrue("geometric should be one (n = 1) instead it is " + u.getGeometricMean(),
                u.getGeometricMean() == one);
        Assert.assertTrue("Std should be zero (n = 1)",
                u.getStandardDeviation() == 0.0);
        Assert.assertTrue("variance should be zero (n = 1)",
                u.getVariance() == 0.0);

        /* n=2 */
        u.addValue(twoF);
        Assert.assertTrue("Std should not be zero (n = 2)",
                u.getStandardDeviation() != 0.0);
        Assert.assertTrue("variance should not be zero (n = 2)",
                u.getVariance() != 0.0);

    }

    @Test
    public void testProductAndGeometricMean() {
        SummaryStatistics u = createSummaryStatistics();
        u.addValue( 1.0 );
        u.addValue( 2.0 );
        u.addValue( 3.0 );
        u.addValue( 4.0 );

        Assert.assertEquals( "Geometric mean not expected", 2.213364,
                u.getGeometricMean(), 0.00001 );
    }

    @Test
    public void testNaNContracts() {
        SummaryStatistics u = createSummaryStatistics();
        Assert.assertTrue("mean not NaN",Double.isNaN(u.getMean()));
        Assert.assertTrue("min not NaN",Double.isNaN(u.getMin()));
        Assert.assertTrue("std dev not NaN",Double.isNaN(u.getStandardDeviation()));
        Assert.assertTrue("var not NaN",Double.isNaN(u.getVariance()));
        Assert.assertTrue("geom mean not NaN",Double.isNaN(u.getGeometricMean()));

        u.addValue(1.0);

        Assert.assertEquals( "mean not expected", 1.0,
                u.getMean(), Double.MIN_VALUE);
        Assert.assertEquals( "variance not expected", 0.0,
                u.getVariance(), Double.MIN_VALUE);
        Assert.assertEquals( "geometric mean not expected", 1.0,
                u.getGeometricMean(), Double.MIN_VALUE);

        u.addValue(-1.0);

        Assert.assertTrue("geom mean not NaN",Double.isNaN(u.getGeometricMean()));

        u.addValue(0.0);

        Assert.assertTrue("geom mean not NaN",Double.isNaN(u.getGeometricMean()));

        //FiXME: test all other NaN contract specs
    }

    @Test
    public void testGetSummary() {
        SummaryStatistics u = createSummaryStatistics();
        StatisticalSummary summary = u.getSummary();
        verifySummary(u, summary);
        u.addValue(1d);
        summary = u.getSummary();
        verifySummary(u, summary);
        u.addValue(2d);
        summary = u.getSummary();
        verifySummary(u, summary);
        u.addValue(2d);
        summary = u.getSummary();
        verifySummary(u, summary);
    }

    @Test
    public void testSerialization() {
        SummaryStatistics u = createSummaryStatistics();
        // Empty test
        TestUtils.checkSerializedEquality(u);
        SummaryStatistics s = (SummaryStatistics) TestUtils.serializeAndRecover(u);
        StatisticalSummary summary = s.getSummary();
        verifySummary(u, summary);

        // Add some data
        u.addValue(2d);
        u.addValue(1d);
        u.addValue(3d);
        u.addValue(4d);
        u.addValue(5d);

        // Test again
        TestUtils.checkSerializedEquality(u);
        s = (SummaryStatistics) TestUtils.serializeAndRecover(u);
        summary = s.getSummary();
        verifySummary(u, summary);

    }

    @Test
    public void testEqualsAndHashCode() {
        SummaryStatistics u = createSummaryStatistics();
        SummaryStatistics t = null;
        int emptyHash = u.hashCode();
        Assert.assertTrue("reflexive", u.equals(u));
        Assert.assertFalse("non-null compared to null", u.equals(t));
        Assert.assertFalse("wrong type", u.equals(Double.valueOf(0)));
        t = createSummaryStatistics();
        Assert.assertTrue("empty instances should be equal", t.equals(u));
        Assert.assertTrue("empty instances should be equal", u.equals(t));
        Assert.assertEquals("empty hash code", emptyHash, t.hashCode());

        // Add some data to u
        u.addValue(2d);
        u.addValue(1d);
        u.addValue(3d);
        u.addValue(4d);
        Assert.assertFalse("different n's should make instances not equal", t.equals(u));
        Assert.assertFalse("different n's should make instances not equal", u.equals(t));
        Assert.assertTrue("different n's should make hashcodes different",
                u.hashCode() != t.hashCode());

        //Add data in same order to t
        t.addValue(2d);
        t.addValue(1d);
        t.addValue(3d);
        t.addValue(4d);
        Assert.assertTrue("summaries based on same data should be equal", t.equals(u));
        Assert.assertTrue("summaries based on same data should be equal", u.equals(t));
        Assert.assertEquals("summaries based on same data should have same hashcodes",
                u.hashCode(), t.hashCode());

        // Clear and make sure summaries are indistinguishable from empty summary
        u.clear();
        t.clear();
        Assert.assertTrue("empty instances should be equal", t.equals(u));
        Assert.assertTrue("empty instances should be equal", u.equals(t));
        Assert.assertEquals("empty hash code", emptyHash, t.hashCode());
        Assert.assertEquals("empty hash code", emptyHash, u.hashCode());
    }

    @Test
    public void testCopy() {
        SummaryStatistics u = createSummaryStatistics();
        u.addValue(2d);
        u.addValue(1d);
        u.addValue(3d);
        u.addValue(4d);
        SummaryStatistics v = new SummaryStatistics(u);
        Assert.assertEquals(u, v);
        Assert.assertEquals(v, u);

        // Make sure both behave the same with additional values added
        u.addValue(7d);
        u.addValue(9d);
        u.addValue(11d);
        u.addValue(23d);
        v.addValue(7d);
        v.addValue(9d);
        v.addValue(11d);
        v.addValue(23d);
        Assert.assertEquals(u, v);
        Assert.assertEquals(v, u);

        // Check implementation pointers are preserved
        u.clear();
        u.setSumImpl(new Sum());
        SummaryStatistics.copy(u,v);
        Assert.assertEquals(u.getSumImpl(), v.getSumImpl());

    }

    private void verifySummary(SummaryStatistics u, StatisticalSummary s) {
        Assert.assertEquals("N",s.getN(),u.getN());
        TestUtils.assertEquals("sum",s.getSum(),u.getSum(),tolerance);
        TestUtils.assertEquals("var",s.getVariance(),u.getVariance(),tolerance);
        TestUtils.assertEquals("std",s.getStandardDeviation(),u.getStandardDeviation(),tolerance);
        TestUtils.assertEquals("mean",s.getMean(),u.getMean(),tolerance);
        TestUtils.assertEquals("min",s.getMin(),u.getMin(),tolerance);
        TestUtils.assertEquals("max",s.getMax(),u.getMax(),tolerance);
    }

    @Test
    public void testSetterInjection() {
        SummaryStatistics u = createSummaryStatistics();
        u.setMeanImpl(new Sum());
        u.setSumLogImpl(new Sum());
        u.addValue(1);
        u.addValue(3);
        Assert.assertEquals(4, u.getMean(), 1E-14);
        Assert.assertEquals(4, u.getSumOfLogs(), 1E-14);
        Assert.assertEquals(FastMath.exp(2), u.getGeometricMean(), 1E-14);
        u.clear();
        u.addValue(1);
        u.addValue(2);
        Assert.assertEquals(3, u.getMean(), 1E-14);
        u.clear();
        u.setMeanImpl(new Mean()); // OK after clear
    }

    @Test
    public void testSetterIllegalState() {
        SummaryStatistics u = createSummaryStatistics();
        u.addValue(1);
        u.addValue(3);
        try {
            u.setMeanImpl(new Sum());
            Assert.fail("Expecting IllegalStateException");
        } catch (IllegalStateException ex) {
            // expected
        }
    }

    @Test
    public void testQuadraticMean() {
        final double[] values = { 1.2, 3.4, 5.6, 7.89 };
        final SummaryStatistics stats = createSummaryStatistics();

        final int len = values.length;
        double expected = 0;
        for (int i = 0; i < len; i++) {
            final double v = values[i];
            expected += v * v / len;

            stats.addValue(v);
        }
        expected = Math.sqrt(expected);

        Assert.assertEquals(expected, stats.getQuadraticMean(), Math.ulp(expected));
    }

    /**
     * JIRA: MATH-691
     */
    @Test
    public void testOverrideVarianceWithMathClass() {
        double[] scores = {1, 2, 3, 4};
        SummaryStatistics stats = new SummaryStatistics();
        stats.setVarianceImpl(new Variance(false)); //use "population variance"
        for(double i : scores) {
          stats.addValue(i);
        }
        Assert.assertEquals((new Variance(false)).evaluate(scores),stats.getVariance(), 0);
    }

    @Test
    public void testOverrideMeanWithMathClass() {
        double[] scores = {1, 2, 3, 4};
        SummaryStatistics stats = new SummaryStatistics();
        stats.setMeanImpl(new Mean());
        for(double i : scores) {
          stats.addValue(i);
        }
        Assert.assertEquals((new Mean()).evaluate(scores),stats.getMean(), 0);
    }

    @Test
    public void testOverrideGeoMeanWithMathClass() {
        double[] scores = {1, 2, 3, 4};
        SummaryStatistics stats = new SummaryStatistics();
        stats.setGeoMeanImpl(new GeometricMean());
        for(double i : scores) {
          stats.addValue(i);
        }
        Assert.assertEquals((new GeometricMean()).evaluate(scores),stats.getGeometricMean(), 0);
    }

    @Test
    public void testToString() {
        SummaryStatistics u = createSummaryStatistics();
        for (int i = 0; i < 5; i++) {
            u.addValue(i);
        }
        final String[] labels = {"min", "max", "sum", "geometric mean", "variance",
                "population variance", "second moment", "sum of squares", "standard deviation",
        "sum of logs"};
        final double[] values = {u.getMin(), u.getMax(), u.getSum(), u.getGeometricMean(),
                u.getVariance(), u.getPopulationVariance(), u.getSecondMoment(), u.getSumsq(),
                u.getStandardDeviation(), u.getSumOfLogs()};
        final String toString = u.toString();
        Assert.assertTrue(toString.indexOf("n: " + u.getN()) > 0); // getN() returns a long
        for (int i = 0; i < values.length; i++) {
            Assert.assertTrue(toString.indexOf(labels[i] + ": " + String.valueOf(values[i])) > 0);
        }
    }
}

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