src/test/java/org/apache/commons/math4/stat/descriptive/moment/VectorialMeanTest.java

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package org.apache.commons.math4.stat.descriptive.moment;

import org.apache.commons.math4.TestUtils;
import org.apache.commons.math4.exception.DimensionMismatchException;
import org.apache.commons.math4.stat.descriptive.moment.VectorialMean;
import org.junit.Test;
import org.junit.Assert;

public class VectorialMeanTest {
    private double[][] points;

    public VectorialMeanTest() {
        points = new double[][] {
            { 1.2, 2.3,  4.5},
            {-0.7, 2.3,  5.0},
            { 3.1, 0.0, -3.1},
            { 6.0, 1.2,  4.2},
            {-0.7, 2.3,  5.0}
        };
    }

    @Test
    public void testMismatch() {
        try {
            new VectorialMean(8).increment(new double[5]);
            Assert.fail("an exception should have been thrown");
        } catch (DimensionMismatchException dme) {
            Assert.assertEquals(5, dme.getArgument());
            Assert.assertEquals(8, dme.getDimension());
        }
    }

    @Test
    public void testSimplistic() {
        VectorialMean stat = new VectorialMean(2);
        stat.increment(new double[] {-1.0,  1.0});
        stat.increment(new double[] { 1.0, -1.0});
        double[] mean = stat.getResult();
        Assert.assertEquals(0.0, mean[0], 1.0e-12);
        Assert.assertEquals(0.0, mean[1], 1.0e-12);
    }

    @Test
    public void testBasicStats() {

        VectorialMean stat = new VectorialMean(points[0].length);
        for (int i = 0; i < points.length; ++i) {
            stat.increment(points[i]);
        }

        Assert.assertEquals(points.length, stat.getN());

        double[] mean = stat.getResult();
        double[]   refMean = new double[] { 1.78, 1.62,  3.12};

        for (int i = 0; i < mean.length; ++i) {
            Assert.assertEquals(refMean[i], mean[i], 1.0e-12);
        }

    }

    @Test
    public void testSerial() {
        VectorialMean stat = new VectorialMean(points[0].length);
        for (int i = 0; i < points.length; ++i) {
            stat.increment(points[i]);
        }
        Assert.assertEquals(stat, TestUtils.serializeAndRecover(stat));
    }
}