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Removed dependency on DistributionFactory. Added settable chi-squared distribution field. 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@545174 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Brent Worden 2007-06-07 13:30:19 +00:00
parent 879a6c0e07
commit 52775a6b76
1 changed files with 32 additions and 19 deletions
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51
src/java/org/apache/commons/math/stat/inference/ChiSquareTestImpl.java
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@ -17,8 +17,9 @@
package org.apache.commons.math.stat.inference;
import org.apache.commons.math.MathException;
import org.apache.commons.math.distribution.DistributionFactory;
import org.apache.commons.math.distribution.ChiSquaredDistribution;
import org.apache.commons.math.distribution.ChiSquaredDistributionImpl;
import org.apache.commons.math.distribution.DistributionFactory;
/**
* Implements Chi-Square test statistics defined in the {@link ChiSquareTest} interface.
@ -26,17 +27,27 @@ import org.apache.commons.math.distribution.ChiSquaredDistribution;
* @version $Revision$ $Date$
*/
public class ChiSquareTestImpl implements ChiSquareTest {
/** Cached DistributionFactory used to create ChiSquaredDistribution instances */
private DistributionFactory distributionFactory = null;
/** Distribution used to compute inference statistics. */
private ChiSquaredDistribution distribution;
/**
* Construct a ChiSquareTestImpl
*/
public ChiSquareTestImpl() {
super();
this(new ChiSquaredDistributionImpl(1.0));
}
/**
* Create a test instance using the given distribution for computing
* inference statistics.
* @param x distribution used to compute inference statistics.
* @since 1.2
*/
public ChiSquareTestImpl(ChiSquaredDistribution x) {
super();
setDistribution(x);
}
/**
* @param observed array of observed frequency counts
* @param expected array of expected frequency counts
@ -72,11 +83,9 @@ public class ChiSquareTestImpl implements ChiSquareTest {
*/
public double chiSquareTest(double[] expected, long[] observed)
throws IllegalArgumentException, MathException {
ChiSquaredDistribution chiSquaredDistribution =
getDistributionFactory().createChiSquareDistribution(
(double) expected.length - 1);
return 1 - chiSquaredDistribution.cumulativeProbability(
chiSquare(expected, observed));
distribution.setDegreesOfFreedom(expected.length - 1.0);
return 1.0 - distribution.cumulativeProbability(
chiSquare(expected, observed));
}
/**
@ -143,9 +152,8 @@ public class ChiSquareTestImpl implements ChiSquareTest {
throws IllegalArgumentException, MathException {
checkArray(counts);
double df = ((double) counts.length -1) * ((double) counts[0].length - 1);
ChiSquaredDistribution chiSquaredDistribution =
getDistributionFactory().createChiSquareDistribution(df);
return 1 - chiSquaredDistribution.cumulativeProbability(chiSquare(counts));
distribution.setDegreesOfFreedom(df);
return 1 - distribution.cumulativeProbability(chiSquare(counts));
}
/**
@ -195,14 +203,11 @@ public class ChiSquareTestImpl implements ChiSquareTest {
//--------------------- Protected methods ---------------------------------
/**
* Gets a DistributionFactory to use in creating ChiSquaredDistribution instances.
*
* @return a DistributionFactory
* @deprecated inject ChiSquaredDistribution instances directly instead of
* using a factory.
*/
protected DistributionFactory getDistributionFactory() {
if (distributionFactory == null) {
distributionFactory = DistributionFactory.newInstance();
}
return distributionFactory;
return DistributionFactory.newInstance();
}
//--------------------- Private array methods -- should find a utility home for these
@ -277,4 +282,12 @@ public class ChiSquareTestImpl implements ChiSquareTest {
return true;
}
/**
* Modify the distribution used to compute inference statistics.
* @param value the new distribution
* @since 1.2
*/
public void setDistribution(ChiSquaredDistribution value) {
distribution = value;
}
}