weka.attributeSelection
Class InfoGainAttributeEval

java.lang.Object
  weka.attributeSelection.ASEvaluation
      weka.attributeSelection.InfoGainAttributeEval

All Implemented Interfaces:

Serializable, AttributeEvaluator, CapabilitiesHandler, OptionHandler, RevisionHandler

public class InfoGainAttributeEval
extends ASEvaluation
implements AttributeEvaluator, OptionHandler

InfoGainAttributeEval :

Evaluates the worth of an attribute by measuring the information gain with respect to the class.

InfoGain(Class,Attribute) = H(Class) - H(Class | Attribute).

Valid options are:

 -M
  treat missing values as a seperate value.

 -B
  just binarize numeric attributes instead 
  of properly discretizing them.

Version:

$Revision: 8034 $

Author:

Mark Hall (mhall@cs.waikato.ac.nz)

See Also:

Discretize, NumericToBinary, Serialized Form

Constructor Summary

InfoGainAttributeEval()
Constructor

Method Summary

String	binarizeNumericAttributesTipText() Returns the tip text for this property
void	buildEvaluator(Instances data) Initializes an information gain attribute evaluator.
double	evaluateAttribute(int attribute) evaluates an individual attribute by measuring the amount of information gained about the class given the attribute.
boolean	getBinarizeNumericAttributes() get whether numeric attributes are just being binarized.
Capabilities	getCapabilities() Returns the capabilities of this evaluator.
boolean	getMissingMerge() get whether missing values are being distributed or not
String[]	getOptions() Gets the current settings of WrapperSubsetEval.
String	getRevision() Returns the revision string.
String	globalInfo() Returns a string describing this attribute evaluator
Enumeration	listOptions() Returns an enumeration describing the available options.
static void	main(String[] args) Main method for testing this class.
String	missingMergeTipText() Returns the tip text for this property
void	setBinarizeNumericAttributes(boolean b) Binarize numeric attributes.
void	setMissingMerge(boolean b) distribute the counts for missing values across observed values
void	setOptions(String[] options) Parses a given list of options.
String	toString() Describe the attribute evaluator

Methods inherited from class weka.attributeSelection.ASEvaluation

forName, makeCopies, postProcess, runEvaluator

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

InfoGainAttributeEval

public InfoGainAttributeEval()

Constructor

Method Detail

globalInfo

public 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 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(String[] options)
                throws 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:

Exception - if an option is not supported

getOptions

public 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 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 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.

getCapabilities

public Capabilities getCapabilities()

Returns the capabilities of this evaluator.

Specified by:

getCapabilities in interface CapabilitiesHandler

Overrides:

getCapabilities in class ASEvaluation

Returns:

the capabilities of this evaluator

See Also:

Capabilities

buildEvaluator

public void buildEvaluator(Instances data)
                    throws Exception

Initializes an information gain attribute evaluator. Discretizes all attributes that are numeric.

Specified by:

buildEvaluator in class ASEvaluation

Parameters:

data - set of instances serving as training data

Throws:

Exception - if the evaluator has not been generated successfully

evaluateAttribute

public double evaluateAttribute(int attribute)
                         throws Exception

evaluates an individual attribute by measuring the amount of information gained about the class given the attribute.

Specified by:

evaluateAttribute in interface AttributeEvaluator

Parameters:

attribute - the index of the attribute to be evaluated

Returns:

the info gain

Throws:

Exception - if the attribute could not be evaluated

toString

public String toString()

Describe the attribute evaluator

Overrides:

toString in class Object

Returns:

a description of the attribute evaluator as a string

getRevision

public String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Overrides:

getRevision in class ASEvaluation

Returns:

the revision

main

public static void main(String[] args)

Main method for testing this class.

Parameters:

args - the options