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Commons Math example source code file (StatUtilsTest.java)

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

Java - Commons Math tags/keywords

didn't, exception, exception, expecting, expecting, illegalargumentexception, illegalargumentexception, mean, nan, statutilstest, sum, sum, testcase, variance

The Commons Math StatUtilsTest.java 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.math.stat;

import junit.framework.TestCase;

import org.apache.commons.math.TestUtils;

/**
 * Test cases for the {@link StatUtils} class.
 * @version $Revision: 902201 $ $Date: 2010-01-22 13:18:16 -0500 (Fri, 22 Jan 2010) $
 */

public final class StatUtilsTest extends TestCase {

    private double one = 1;
    private float two = 2;
    private int three = 3;
    private double mean = 2;
    private double sumSq = 18;
    private double sum = 8;
    private double var = 0.666666666666666666667;
    private double min = 1;
    private double max = 3;
    private double tolerance = 10E-15;
    private double nan = Double.NaN;

    public StatUtilsTest(String name) {
        super(name);
    }

    /** test stats */
    public void testStats() {
        double[] values = new double[] { one, two, two, three };
        assertEquals("sum", sum, StatUtils.sum(values), tolerance);
        assertEquals("sumsq", sumSq, StatUtils.sumSq(values), tolerance);
        assertEquals("var", var, StatUtils.variance(values), tolerance);
        assertEquals("var with mean", var, StatUtils.variance(values, mean), tolerance);
        assertEquals("mean", mean, StatUtils.mean(values), tolerance);
        assertEquals("min", min, StatUtils.min(values), tolerance);
        assertEquals("max", max, StatUtils.max(values), tolerance);
    }

    public void testN0andN1Conditions() throws Exception {
        double[] values = new double[0];

        assertTrue(
            "Mean of n = 0 set should be NaN",
            Double.isNaN(StatUtils.mean(values)));
        assertTrue(
            "Variance of n = 0 set should be NaN",
            Double.isNaN(StatUtils.variance(values)));

        values = new double[] { one };

        assertTrue(
            "Mean of n = 1 set should be value of single item n1",
            StatUtils.mean(values) == one);
        assertTrue(
            "Variance of n = 1 set should be zero",
            StatUtils.variance(values) == 0);
    }

    public void testArrayIndexConditions() throws Exception {
        double[] values = { 1.0, 2.0, 3.0, 4.0 };

        assertEquals(
            "Sum not expected",
            5.0,
            StatUtils.sum(values, 1, 2),
            Double.MIN_VALUE);
        assertEquals(
            "Sum not expected",
            3.0,
            StatUtils.sum(values, 0, 2),
            Double.MIN_VALUE);
        assertEquals(
            "Sum not expected",
            7.0,
            StatUtils.sum(values, 2, 2),
            Double.MIN_VALUE);

        try {
            StatUtils.sum(values, 2, 3);
            assertTrue("Didn't throw exception", false);
        } catch (Exception e) {
            assertTrue(true);
        }

        try {
            StatUtils.sum(values, -1, 2);
            assertTrue("Didn't throw exception", false);
        } catch (Exception e) {
            assertTrue(true);
        }

    }

    public void testSumSq() {
        double[] x = null;

        // test null
        try {
            StatUtils.sumSq(x);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        try {
            StatUtils.sumSq(x, 0, 4);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.sumSq(x), tolerance);
        TestUtils.assertEquals(Double.NaN, StatUtils.sumSq(x, 0, 0), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(4, StatUtils.sumSq(x), tolerance);
        TestUtils.assertEquals(4, StatUtils.sumSq(x, 0, 1), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(18, StatUtils.sumSq(x), tolerance);
        TestUtils.assertEquals(8, StatUtils.sumSq(x, 1, 2), tolerance);
    }

    public void testProduct() {
        double[] x = null;

        // test null
        try {
            StatUtils.product(x);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        try {
            StatUtils.product(x, 0, 4);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.product(x), tolerance);
        TestUtils.assertEquals(Double.NaN, StatUtils.product(x, 0, 0), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(two, StatUtils.product(x), tolerance);
        TestUtils.assertEquals(two, StatUtils.product(x, 0, 1), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(12, StatUtils.product(x), tolerance);
        TestUtils.assertEquals(4, StatUtils.product(x, 1, 2), tolerance);
    }

    public void testSumLog() {
        double[] x = null;

        // test null
        try {
            StatUtils.sumLog(x);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        try {
            StatUtils.sumLog(x, 0, 4);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.sumLog(x), tolerance);
        TestUtils.assertEquals(Double.NaN, StatUtils.sumLog(x, 0, 0), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(Math.log(two), StatUtils.sumLog(x), tolerance);
        TestUtils.assertEquals(Math.log(two), StatUtils.sumLog(x, 0, 1), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(Math.log(one) + 2.0 * Math.log(two) + Math.log(three), StatUtils.sumLog(x), tolerance);
        TestUtils.assertEquals(2.0 * Math.log(two), StatUtils.sumLog(x, 1, 2), tolerance);
    }

    public void testMean() {
        double[] x = null;

        try {
            StatUtils.mean(x, 0, 4);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.mean(x, 0, 0), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(two, StatUtils.mean(x, 0, 1), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(2.5, StatUtils.mean(x, 2, 2), tolerance);
    }

    public void testVariance() {
        double[] x = null;

        try {
            StatUtils.variance(x, 0, 4);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.variance(x, 0, 0), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(0.0, StatUtils.variance(x, 0, 1), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(0.5, StatUtils.variance(x, 2, 2), tolerance);

        // test precomputed mean
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(0.5, StatUtils.variance(x,2.5, 2, 2), tolerance);
    }

    public void testMax() {
        double[] x = null;

        try {
            StatUtils.max(x, 0, 4);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.max(x, 0, 0), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(two, StatUtils.max(x, 0, 1), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(three, StatUtils.max(x, 1, 3), tolerance);

        // test first nan is ignored
        x = new double[] {nan, two, three};
        TestUtils.assertEquals(three, StatUtils.max(x), tolerance);

        // test middle nan is ignored
        x = new double[] {one, nan, three};
        TestUtils.assertEquals(three, StatUtils.max(x), tolerance);

        // test last nan is ignored
        x = new double[] {one, two, nan};
        TestUtils.assertEquals(two, StatUtils.max(x), tolerance);

        // test all nan returns nan
        x = new double[] {nan, nan, nan};
        TestUtils.assertEquals(nan, StatUtils.max(x), tolerance);
    }

    public void testMin() {
        double[] x = null;

        try {
            StatUtils.min(x, 0, 4);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.min(x, 0, 0), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(two, StatUtils.min(x, 0, 1), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(two, StatUtils.min(x, 1, 3), tolerance);

        // test first nan is ignored
        x = new double[] {nan, two, three};
        TestUtils.assertEquals(two, StatUtils.min(x), tolerance);

        // test middle nan is ignored
        x = new double[] {one, nan, three};
        TestUtils.assertEquals(one, StatUtils.min(x), tolerance);

        // test last nan is ignored
        x = new double[] {one, two, nan};
        TestUtils.assertEquals(one, StatUtils.min(x), tolerance);

        // test all nan returns nan
        x = new double[] {nan, nan, nan};
        TestUtils.assertEquals(nan, StatUtils.min(x), tolerance);
    }

    public void testPercentile() {
        double[] x = null;

        // test null
        try {
            StatUtils.percentile(x, .25);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        try {
            StatUtils.percentile(x, 0, 4, 0.25);
            fail("null is not a valid data array.");
        } catch (IllegalArgumentException ex) {
            // success
        }

        // test empty
        x = new double[] {};
        TestUtils.assertEquals(Double.NaN, StatUtils.percentile(x, 25), tolerance);
        TestUtils.assertEquals(Double.NaN, StatUtils.percentile(x, 0, 0, 25), tolerance);

        // test one
        x = new double[] {two};
        TestUtils.assertEquals(two, StatUtils.percentile(x, 25), tolerance);
        TestUtils.assertEquals(two, StatUtils.percentile(x, 0, 1, 25), tolerance);

        // test many
        x = new double[] {one, two, two, three};
        TestUtils.assertEquals(2.5, StatUtils.percentile(x, 70), tolerance);
        TestUtils.assertEquals(2.5, StatUtils.percentile(x, 1, 3, 62.5), tolerance);
    }

    public void testDifferenceStats() throws Exception {
        double sample1[] = {1d, 2d, 3d, 4d};
        double sample2[] = {1d, 3d, 4d, 2d};
        double diff[] = {0d, -1d, -1d, 2d};
        double small[] = {1d, 4d};
        double meanDifference = StatUtils.meanDifference(sample1, sample2);
        assertEquals(StatUtils.sumDifference(sample1, sample2), StatUtils.sum(diff), tolerance);
        assertEquals(meanDifference, StatUtils.mean(diff), tolerance);
        assertEquals(StatUtils.varianceDifference(sample1, sample2, meanDifference),
                StatUtils.variance(diff), tolerance);
        try {
            StatUtils.meanDifference(sample1, small);
            fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException ex) {
            // expected
        }
        try {
            StatUtils.varianceDifference(sample1, small, meanDifference);
            fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException ex) {
            // expected
        }
        try {
            double[] single = {1.0};
            StatUtils.varianceDifference(single, single, meanDifference);
            fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException ex) {
            // expected
        }
    }

    public void testGeometricMean() throws Exception {
        double[] test = null;
        try {
            StatUtils.geometricMean(test);
            fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException ex) {
            // expected
        }
        test = new double[] {2, 4, 6, 8};
        assertEquals(Math.exp(0.25d * StatUtils.sumLog(test)),
                StatUtils.geometricMean(test), Double.MIN_VALUE);
        assertEquals(Math.exp(0.5 * StatUtils.sumLog(test, 0, 2)),
                StatUtils.geometricMean(test, 0, 2), Double.MIN_VALUE);
    }
}

Other Commons Math examples (source code examples)

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