org.apache.ctakes.temporal.ae.feature.selection

Class Chi2FeatureSelection<OUTCOME_T>

java.lang.Object

org.apache.ctakes.temporal.ae.feature.selection.FeatureSelection<OUTCOME_T>

org.apache.ctakes.temporal.ae.feature.selection.Chi2FeatureSelection<OUTCOME_T>

public class Chi2FeatureSelection<OUTCOME_T>
extends FeatureSelection<OUTCOME_T>

Selects features via Chi-squared statistics between the features extracted from its sub-extractor and the outcome values they are paired with in classification instances.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	Chi2FeatureSelection.Chi2Scorer<OUTCOME_T> Helper class for aggregating and computing mutual Chi2 statistics

Field Summary

Fields

Modifier and Type	Field and Description
private Chi2FeatureSelection.Chi2Scorer<OUTCOME_T>	chi2Function
private double	chi2Threshold the percentage of total features that would be returned.
private java.util.LinkedHashSet<java.lang.String>	discardedFeatureNames
private int	numFeatures
private boolean	yates

Fields inherited from class org.apache.ctakes.temporal.ae.feature.selection.FeatureSelection

isTrained, selectedFeatureNames

Constructor Summary

Constructors

Constructor and Description
Chi2FeatureSelection(java.lang.String name)
Chi2FeatureSelection(java.lang.String name, double threshold)
Chi2FeatureSelection(java.lang.String name, double threshold, boolean yates) Constructor that can let use control the yate's correction

Method Summary

Methods

Modifier and Type	Method and Description
boolean	apply(Feature feature)
void	load(java.net.URI uri)
void	save(java.net.URI uri)
void	train(java.lang.Iterable<> instances)

Methods inherited from class org.apache.ctakes.temporal.ae.feature.selection.FeatureSelection

getFeatureName, transform, transform

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

chi2Threshold

private double chi2Threshold

the percentage of total features that would be returned. range from 0% - 100%, i.e. [0,1]

numFeatures

private int numFeatures

chi2Function

private Chi2FeatureSelection.Chi2Scorer<OUTCOME_T> chi2Function

yates

private boolean yates

discardedFeatureNames

private java.util.LinkedHashSet<java.lang.String> discardedFeatureNames

Constructor Detail

Chi2FeatureSelection

public Chi2FeatureSelection(java.lang.String name)

Chi2FeatureSelection

public Chi2FeatureSelection(java.lang.String name,
                    double threshold)

Chi2FeatureSelection

public Chi2FeatureSelection(java.lang.String name,
                    double threshold,
                    boolean yates)

Constructor that can let use control the yate's correction

Parameters:

name -

threshold -

yates - : true for using yate's correction, false for turn off yate's correction

Method Detail

apply

public boolean apply(Feature feature)

Overrides:

apply in class FeatureSelection<OUTCOME_T>

train

public void train(java.lang.Iterable<> instances)

save

public void save(java.net.URI uri)
          throws java.io.IOException

Throws:

java.io.IOException

load

public void load(java.net.URI uri)
          throws java.io.IOException

Throws:

java.io.IOException