weka.attributeSelection
Class ChiSquaredAttributeEval

java.lang.Object
  weka.attributeSelection.ASEvaluation
      weka.attributeSelection.AttributeEvaluator
          weka.attributeSelection.ChiSquaredAttributeEval

All Implemented Interfaces:

OptionHandler, java.io.Serializable

public class ChiSquaredAttributeEval

extends AttributeEvaluator

implements OptionHandler

Class for Evaluating attributes individually by measuring the chi-squared statistic with respect to the class. Valid options are:

-M
Treat missing values as a seperate value.
-B
Just binarize numeric attributes instead of properly discretizing them.

Version:

$Revision: 1.8 $

Author:

Eibe Frank (eibe@cs.waikato.ac.nz)

See Also:

Serialized Form

Field Summary

private boolean	m_Binarize Just binarize numeric attributes
private double[]	m_ChiSquareds The chi-squared value for each attribute
private boolean	m_missing_merge Treat missing values as a seperate value

Constructor Summary

ChiSquaredAttributeEval()
Constructor

Method Summary

java.lang.String	binarizeNumericAttributesTipText() Returns the tip text for this property
void	buildEvaluator(Instances data) Initializes a chi-squared attribute evaluator.
double	evaluateAttribute(int attribute) evaluates an individual attribute by measuring its chi-squared value.
boolean	getBinarizeNumericAttributes() get whether numeric attributes are just being binarized.
boolean	getMissingMerge() get whether missing values are being distributed or not
java.lang.String[]	getOptions() Gets the current settings of WrapperSubsetEval.
java.lang.String	globalInfo() Returns a string describing this attribute evaluator
java.util.Enumeration	listOptions() Returns an enumeration describing the available options
static void	main(java.lang.String[] args) Main method for testing this class.
java.lang.String	missingMergeTipText() Returns the tip text for this property
protected void	resetOptions() Reset options to their default values
void	setBinarizeNumericAttributes(boolean b) Binarize numeric attributes.
void	setMissingMerge(boolean b) distribute the counts for missing values across observed values
void	setOptions(java.lang.String[] options) Parses a given list of options.
java.lang.String	toString() Describe the attribute evaluator

Methods inherited from class weka.attributeSelection.ASEvaluation

forName, makeCopies, postProcess

Methods inherited from class java.lang.Object

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

Field Detail

m_missing_merge

private boolean m_missing_merge

Treat missing values as a seperate value

m_Binarize

private boolean m_Binarize

Just binarize numeric attributes

m_ChiSquareds

private double[] m_ChiSquareds

The chi-squared value for each attribute

Constructor Detail

ChiSquaredAttributeEval

public ChiSquaredAttributeEval()

Constructor

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing this attribute evaluator

Returns:

a description of the evaluator suitable for displaying in the explorer/experimenter gui

listOptions

public java.util.Enumeration listOptions()

Returns an enumeration describing the available options

Specified by:

listOptions in interface OptionHandler

Returns:

an enumeration of all the available options

setOptions

public void setOptions(java.lang.String[] options)
                throws java.lang.Exception

Parses a given list of options.

Valid options are:

-M
Treat missing values as a seperate value.
-B
Just binarize numeric attributes instead of properly discretizing them.

Specified by:

setOptions in interface OptionHandler

Parameters:

options - the list of options as an array of strings

Throws:

java.lang.Exception - if an option is not supported

getOptions

public java.lang.String[] getOptions()

Gets the current settings of WrapperSubsetEval.

Specified by:

getOptions in interface OptionHandler

Returns:

an array of strings suitable for passing to setOptions()

binarizeNumericAttributesTipText

public java.lang.String binarizeNumericAttributesTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setBinarizeNumericAttributes

public void setBinarizeNumericAttributes(boolean b)

Binarize numeric attributes.

Parameters:

b - true=binarize numeric attributes

getBinarizeNumericAttributes

public boolean getBinarizeNumericAttributes()

get whether numeric attributes are just being binarized.

Returns:

true if missing values are being distributed.

missingMergeTipText

public java.lang.String missingMergeTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setMissingMerge

public void setMissingMerge(boolean b)

distribute the counts for missing values across observed values

Parameters:

b - true=distribute missing values.

getMissingMerge

public boolean getMissingMerge()

get whether missing values are being distributed or not

Returns:

true if missing values are being distributed.

buildEvaluator

public void buildEvaluator(Instances data)
                    throws java.lang.Exception

Initializes a chi-squared attribute evaluator. Discretizes all attributes that are numeric.

Specified by:

buildEvaluator in class ASEvaluation

Parameters:

data - set of instances serving as training data

Throws:

java.lang.Exception - if the evaluator has not been generated successfully

resetOptions

protected void resetOptions()

Reset options to their default values

evaluateAttribute

public double evaluateAttribute(int attribute)
                         throws java.lang.Exception

evaluates an individual attribute by measuring its chi-squared value.

Specified by:

evaluateAttribute in class AttributeEvaluator

Parameters:

attribute - the index of the attribute to be evaluated

Returns:

the "merit" of the attribute

Throws:

java.lang.Exception - if the attribute could not be evaluated

toString

public java.lang.String toString()

Describe the attribute evaluator

Returns:

a description of the attribute evaluator as a string

main

public static void main(java.lang.String[] args)

Main method for testing this class.