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package org.apache.commons.math.stat.univariate;
import org.apache.commons.math.stat.DescriptiveStatistics;
import org.apache.commons.math.stat.StorelessDescriptiveStatisticsImpl;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
/**
* Test cases for the {@link DescriptiveStatistics} class.
*
* @version $Revision: 1.1 $ $Date: 2003/11/15 16:01:41 $
*/
public final class UnivariateImplTest extends TestCase {
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 std = Math.sqrt(var);
private double n = 4;
private double min = 1;
private double max = 3;
private double tolerance = 10E-15;
public UnivariateImplTest(String name) {
super(name);
}
public void setUp() {
}
public static Test suite() {
TestSuite suite = new TestSuite(UnivariateImplTest.class);
suite.setName("Frequency Tests");
return suite;
}
/** test stats */
public void testStats() {
StorelessDescriptiveStatisticsImpl u = new StorelessDescriptiveStatisticsImpl();
assertEquals("total count",0,u.getN(),tolerance);
u.addValue(one);
u.addValue(twoF);
u.addValue(twoL);
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 {
StorelessDescriptiveStatisticsImpl u = new StorelessDescriptiveStatisticsImpl();
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() ) );
assertTrue("skew of n = 0 set should be NaN",
Double.isNaN(u.getSkewness() ) );
assertTrue("kurtosis of n = 0 set should be NaN",
Double.isNaN(u.getKurtosis() ) );
/* n=1 */
u.addValue(one);
assertTrue("mean should be one (n = 1)",
u.getMean() == one);
assertTrue("geometric should be one (n = 1) instead it is " + u.getGeometricMean(),
u.getGeometricMean() == one);
assertTrue("Std should be zero (n = 1)",
u.getStandardDeviation() == 0.0);
assertTrue("variance should be zero (n = 1)",
u.getVariance() == 0.0);
assertTrue("skew should be zero (n = 1)",
u.getSkewness() == 0.0);
assertTrue("kurtosis should be zero (n = 1)",
u.getKurtosis() == 0.0);
/* n=2 */
u.addValue(twoF);
assertTrue("Std should not be zero (n = 2)",
u.getStandardDeviation() != 0.0);
assertTrue("variance should not be zero (n = 2)",
u.getVariance() != 0.0);
assertTrue("skew should not be zero (n = 2)",
u.getSkewness() == 0.0);
assertTrue("kurtosis should be zero (n = 2)",
u.getKurtosis() == 0.0);
/* n=3 */
u.addValue(twoL);
assertTrue("skew should not be zero (n = 3)",
u.getSkewness() != 0.0);
assertTrue("kurtosis should be zero (n = 3)",
u.getKurtosis() == 0.0);
/* n=4 */
u.addValue(three);
assertTrue("kurtosis should not be zero (n = 4)",
u.getKurtosis() != 0.0);
}
public void testProductAndGeometricMean() throws Exception {
StorelessDescriptiveStatisticsImpl u = new StorelessDescriptiveStatisticsImpl(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 );
}
public void testRollingMinMax() {
StorelessDescriptiveStatisticsImpl u = new StorelessDescriptiveStatisticsImpl(3);
u.addValue( 1.0 );
u.addValue( 5.0 );
u.addValue( 3.0 );
u.addValue( 4.0 ); // discarding min
assertEquals( "min not expected", 3.0,
u.getMin(), Double.MIN_VALUE);
u.addValue(1.0); // discarding max
assertEquals( "max not expected", 4.0,
u.getMax(), Double.MIN_VALUE);
}
public void testNaNContracts() {
StorelessDescriptiveStatisticsImpl u = new StorelessDescriptiveStatisticsImpl();
double nan = Double.NaN;
assertTrue("mean not NaN",Double.isNaN(u.getMean()));
assertTrue("min not NaN",Double.isNaN(u.getMin()));
assertTrue("std dev not NaN",Double.isNaN(u.getStandardDeviation()));
assertTrue("var not NaN",Double.isNaN(u.getVariance()));
assertTrue("geom mean not NaN",Double.isNaN(u.getGeometricMean()));
u.addValue(1.0);
assertEquals( "mean not expected", 1.0,
u.getMean(), Double.MIN_VALUE);
assertEquals( "variance not expected", 0.0,
u.getVariance(), Double.MIN_VALUE);
assertEquals( "geometric mean not expected", 1.0,
u.getGeometricMean(), Double.MIN_VALUE);
u.addValue(-1.0);
assertTrue("geom mean not NaN",Double.isNaN(u.getGeometricMean()));
u.addValue(0.0);
assertTrue("geom mean not NaN",Double.isNaN(u.getGeometricMean()));
//FiXME: test all other NaN contract specs
}
public void testSkewAndKurtosis() {
DescriptiveStatistics u = new StorelessDescriptiveStatisticsImpl();
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);
}
}