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Commons Math example source code file (ListUnivariateImplTest.java)

This example Commons Math source code file (ListUnivariateImplTest.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

arraylist, arraylist, descriptivestatistics, descriptivestatistics, exception, geometric, list, listunivariateimpl, listunivariateimpl, listunivariateimpltest, mean, n, nan, nan, util

The Commons Math ListUnivariateImplTest.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.descriptive;

import java.util.ArrayList;
import java.util.List;

import junit.framework.TestCase;

import org.apache.commons.math.TestUtils;

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

public final class ListUnivariateImplTest 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 std = Math.sqrt(var);
    private double n = 4;
    private double min = 1;
    private double max = 3;
    private double tolerance = 10E-15;

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

    /** test stats */
    public void testStats() {
        List<Object> externalList = new ArrayList();

        DescriptiveStatistics u = new ListUnivariateImpl( externalList );

        assertEquals("total count",0,u.getN(),tolerance);
        u.addValue(one);
        u.addValue(two);
        u.addValue(two);
        u.addValue(three);
        assertEquals("N",n,u.getN(),tolerance);
        assertEquals("sum",sum,u.getSum(),tolerance);
        assertEquals("sumsq",sumSq,u.getSumsq(),tolerance);
        assertEquals("var",var,u.getVariance(),tolerance);
        assertEquals("std",std,u.getStandardDeviation(),tolerance);
        assertEquals("mean",mean,u.getMean(),tolerance);
        assertEquals("min",min,u.getMin(),tolerance);
        assertEquals("max",max,u.getMax(),tolerance);
        u.clear();
        assertEquals("total count",0,u.getN(),tolerance);
    }

    public void testN0andN1Conditions() throws Exception {
        List<Object> list = new ArrayList();

        DescriptiveStatistics u = new ListUnivariateImpl( list );

        assertTrue("Mean of n = 0 set should be NaN", Double.isNaN( u.getMean() ) );
        assertTrue("Standard Deviation of n = 0 set should be NaN", Double.isNaN( u.getStandardDeviation() ) );
        assertTrue("Variance of n = 0 set should be NaN", Double.isNaN(u.getVariance() ) );

        list.add( Double.valueOf(one));

        assertTrue( "Mean of n = 1 set should be value of single item n1", u.getMean() == one);
        assertTrue( "StdDev of n = 1 set should be zero, instead it is: " + u.getStandardDeviation(), u.getStandardDeviation() == 0);
        assertTrue( "Variance of n = 1 set should be zero", u.getVariance() == 0);
    }

    public void testSkewAndKurtosis() {
        DescriptiveStatistics u = new DescriptiveStatistics();

        double[] testArray = { 12.5, 12, 11.8, 14.2, 14.9, 14.5, 21, 8.2, 10.3, 11.3, 14.1,
                                             9.9, 12.2, 12, 12.1, 11, 19.8, 11, 10, 8.8, 9, 12.3 };
        for( int i = 0; i < testArray.length; i++) {
            u.addValue( testArray[i]);
        }

        assertEquals("mean", 12.40455, u.getMean(), 0.0001);
        assertEquals("variance", 10.00236, u.getVariance(), 0.0001);
        assertEquals("skewness", 1.437424, u.getSkewness(), 0.0001);
        assertEquals("kurtosis", 2.37719, u.getKurtosis(), 0.0001);
    }

    public void testProductAndGeometricMean() throws Exception {
        ListUnivariateImpl u = new ListUnivariateImpl(new ArrayList<Object>());
        u.setWindowSize(10);

        u.addValue( 1.0 );
        u.addValue( 2.0 );
        u.addValue( 3.0 );
        u.addValue( 4.0 );

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

        // Now test rolling - StorelessDescriptiveStatistics should discount the contribution
        // of a discarded element
        for( int i = 0; i < 10; i++ ) {
            u.addValue( i + 2 );
        }
        // Values should be (2,3,4,5,6,7,8,9,10,11)

        assertEquals( "Geometric mean not expected", 5.755931, u.getGeometricMean(), 0.00001 );


    }

    /** test stats */
    public void testSerialization() {

        DescriptiveStatistics u = new ListUnivariateImpl();

        assertEquals("total count",0,u.getN(),tolerance);
        u.addValue(one);
        u.addValue(two);

        DescriptiveStatistics u2 = (DescriptiveStatistics)TestUtils.serializeAndRecover(u);

        u2.addValue(two);
        u2.addValue(three);

        assertEquals("N",n,u2.getN(),tolerance);
        assertEquals("sum",sum,u2.getSum(),tolerance);
        assertEquals("sumsq",sumSq,u2.getSumsq(),tolerance);
        assertEquals("var",var,u2.getVariance(),tolerance);
        assertEquals("std",std,u2.getStandardDeviation(),tolerance);
        assertEquals("mean",mean,u2.getMean(),tolerance);
        assertEquals("min",min,u2.getMin(),tolerance);
        assertEquals("max",max,u2.getMax(),tolerance);

        u2.clear();
        assertEquals("total count",0,u2.getN(),tolerance);
    }
}


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