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Cached DistributionFactory instance. 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@141284 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Phil Steitz 2004-06-06 23:14:09 +00:00
parent d8a43bf62a
commit 444c87274c
1 changed files with 17 additions and 5 deletions
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22
src/java/org/apache/commons/math/stat/inference/ChiSquareTestImpl.java
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@ -15,8 +15,6 @@
*/ */
package org.apache.commons.math.stat.inference; package org.apache.commons.math.stat.inference;
import java.io.Serializable;
import org.apache.commons.math.MathException; import org.apache.commons.math.MathException;
import org.apache.commons.math.distribution.DistributionFactory; import org.apache.commons.math.distribution.DistributionFactory;
import org.apache.commons.math.distribution.ChiSquaredDistribution; import org.apache.commons.math.distribution.ChiSquaredDistribution;
@ -24,9 +22,12 @@ import org.apache.commons.math.distribution.ChiSquaredDistribution;
/** /**
* Implements Chi-Square test statistics defined in the {@link ChiSquareTest} interface. * Implements Chi-Square test statistics defined in the {@link ChiSquareTest} interface.
* *
* @version $Revision: 1.4 $ $Date: 2004/06/05 20:11:06 $ * @version $Revision: 1.5 $ $Date: 2004/06/06 23:14:09 $
*/ */
public class ChiSquareTestImpl implements ChiSquareTest { public class ChiSquareTestImpl implements ChiSquareTest {
/** Cached DistributionFactory used to create ChiSquaredDistribution instances */
private DistributionFactory distributionFactory = null;
public ChiSquareTestImpl() { public ChiSquareTestImpl() {
super(); super();
@ -67,7 +68,7 @@ public class ChiSquareTestImpl implements ChiSquareTest {
public double chiSquareTest(double[] expected, long[] observed) public double chiSquareTest(double[] expected, long[] observed)
throws IllegalArgumentException, MathException { throws IllegalArgumentException, MathException {
ChiSquaredDistribution chiSquaredDistribution = ChiSquaredDistribution chiSquaredDistribution =
DistributionFactory.newInstance().createChiSquareDistribution((double) expected.length - 1); getDistributionFactory().createChiSquareDistribution((double) expected.length - 1);
return 1 - chiSquaredDistribution.cumulativeProbability(chiSquare(expected, observed)); return 1 - chiSquaredDistribution.cumulativeProbability(chiSquare(expected, observed));
} }
@ -135,7 +136,7 @@ public class ChiSquareTestImpl implements ChiSquareTest {
checkArray(counts); checkArray(counts);
double df = ((double) counts.length -1) * ((double) counts[0].length - 1); double df = ((double) counts.length -1) * ((double) counts[0].length - 1);
ChiSquaredDistribution chiSquaredDistribution = ChiSquaredDistribution chiSquaredDistribution =
DistributionFactory.newInstance().createChiSquareDistribution(df); getDistributionFactory().createChiSquareDistribution(df);
return 1 - chiSquaredDistribution.cumulativeProbability(chiSquare(counts)); return 1 - chiSquaredDistribution.cumulativeProbability(chiSquare(counts));
} }
@ -183,6 +184,17 @@ public class ChiSquareTestImpl implements ChiSquareTest {
} }
//--------------------- Protected methods ---------------------------------
/**
* Gets a DistributionFactory to use in creating ChiSquaredDistribution instances.
*/
protected DistributionFactory getDistributionFactory() {
if (distributionFactory == null) {
distributionFactory = DistributionFactory.newInstance();
}
return distributionFactory;
}
//--------------------- Private array methods -- should find a utility home for these //--------------------- Private array methods -- should find a utility home for these
/** /**