weka.attributeSelection
Class Ranker

java.lang.Object
  |
  +--weka.attributeSelection.ASSearch
        |
        +--weka.attributeSelection.Ranker

All Implemented Interfaces:

OptionHandler, RankedOutputSearch, java.io.Serializable, StartSetHandler

public class Ranker

extends ASSearch

implements RankedOutputSearch, StartSetHandler, OptionHandler

Class for ranking the attributes evaluated by a AttributeEvaluator Valid options are:

-P
Specify a starting set of attributes. Eg 1,4,7-9.

-T
Specify a threshold by which the AttributeSelection module can.
discard attributes.

Version:

$Revision: 1.20 $

Author:

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

See Also:

Serialized Form

Constructor Summary

Ranker()
Constructor

Method Summary

java.lang.String	generateRankingTipText() Returns the tip text for this property
int	getCalculatedNumToSelect() Gets the calculated number to select.
boolean	getGenerateRanking() This is a dummy method.
int	getNumToSelect() Gets the number of attributes to be retained.
java.lang.String[]	getOptions() Gets the current settings of ReliefFAttributeEval.
java.lang.String	getStartSet() Returns a list of attributes (and or attribute ranges) as a String
double	getThreshold() Returns the threshold so that the AttributeSelection module can discard attributes from the ranking.
java.lang.String	globalInfo() Returns a string describing this search method
java.util.Enumeration	listOptions() Returns an enumeration describing the available options.
java.lang.String	numToSelectTipText() Returns the tip text for this property
double[][]	rankedAttributes() Sorts the evaluated attribute list
int[]	search(ASEvaluation ASEval, Instances data) Kind of a dummy search algorithm.
void	setGenerateRanking(boolean doRank) This is a dummy set method---Ranker is ONLY capable of producing a ranked list of attributes for attribute evaluators.
void	setNumToSelect(int n) Specify the number of attributes to select from the ranked list.
void	setOptions(java.lang.String[] options) Parses a given list of options.
void	setStartSet(java.lang.String startSet) Sets a starting set of attributes for the search.
void	setThreshold(double threshold) Set the threshold by which the AttributeSelection module can discard attributes.
java.lang.String	startSetTipText() Returns the tip text for this property
java.lang.String	thresholdTipText() Returns the tip text for this property
java.lang.String	toString() returns a description of the search as a String

Methods inherited from class weka.attributeSelection.ASSearch

forName

Methods inherited from class java.lang.Object

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

Constructor Detail

Ranker

public Ranker()

Constructor

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing this search method

Returns:

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

numToSelectTipText

public java.lang.String numToSelectTipText()

Returns the tip text for this property

Returns:

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

setNumToSelect

public void setNumToSelect(int n)

Specify the number of attributes to select from the ranked list. -1 indicates that all attributes are to be retained.

Specified by:

setNumToSelect in interface RankedOutputSearch

Parameters:

n - the number of attributes to retain

getNumToSelect

public int getNumToSelect()

Gets the number of attributes to be retained.

Specified by:

getNumToSelect in interface RankedOutputSearch

Returns:

the number of attributes to retain

getCalculatedNumToSelect

public int getCalculatedNumToSelect()

Gets the calculated number to select. This might be computed from a threshold, or if < 0 is set as the number to select then it is set to the number of attributes in the (transformed) data.

Specified by:

getCalculatedNumToSelect in interface RankedOutputSearch

Returns:

the calculated number of attributes to select

thresholdTipText

public java.lang.String thresholdTipText()

Returns the tip text for this property

Returns:

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

setThreshold

public void setThreshold(double threshold)

Set the threshold by which the AttributeSelection module can discard attributes.

Specified by:

setThreshold in interface RankedOutputSearch

Parameters:

threshold - the threshold.

getThreshold

public double getThreshold()

Returns the threshold so that the AttributeSelection module can discard attributes from the ranking.

Specified by:

getThreshold in interface RankedOutputSearch

Returns:

a threshold by which to discard attributes

generateRankingTipText

public java.lang.String generateRankingTipText()

Returns the tip text for this property

Returns:

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

setGenerateRanking

public void setGenerateRanking(boolean doRank)

This is a dummy set method---Ranker is ONLY capable of producing a ranked list of attributes for attribute evaluators.

Specified by:

setGenerateRanking in interface RankedOutputSearch

Parameters:

doRank - this parameter is N/A and is ignored

getGenerateRanking

public boolean getGenerateRanking()

This is a dummy method. Ranker can ONLY be used with attribute evaluators and as such can only produce a ranked list of attributes

Specified by:

getGenerateRanking in interface RankedOutputSearch

Returns:

true all the time.

startSetTipText

public java.lang.String startSetTipText()

Returns the tip text for this property

Returns:

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

setStartSet

public void setStartSet(java.lang.String startSet)
                 throws java.lang.Exception

Sets a starting set of attributes for the search. It is the search method's responsibility to report this start set (if any) in its toString() method.

Specified by:

setStartSet in interface StartSetHandler

Parameters:

startSet - a string containing a list of attributes (and or ranges), eg. 1,2,6,10-15.

Throws:

java.lang.Exception - if start set can't be set.

getStartSet

public java.lang.String getStartSet()

Returns a list of attributes (and or attribute ranges) as a String

Specified by:

getStartSet in interface StartSetHandler

Returns:

a list of attributes (and or attribute ranges)

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:

-P
Specify a starting set of attributes. Eg 1,4,7-9.

-T
Specify a threshold by which the AttributeSelection module can
discard attributes.

-N
Specify the number of attributes to retain. Overides any threshold.

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 ReliefFAttributeEval.

Specified by:

getOptions in interface OptionHandler

Returns:

an array of strings suitable for passing to setOptions()

search

public int[] search(ASEvaluation ASEval,
                    Instances data)
             throws java.lang.Exception

Kind of a dummy search algorithm. Calls a Attribute evaluator to evaluate each attribute not included in the startSet and then sorts them to produce a ranked list of attributes.

Specified by:

search in class ASSearch

Parameters:

data - the training instances.

ASEval - the attribute evaluator to guide the search

Returns:

an array (not necessarily ordered) of selected attribute indexes

Throws:

java.lang.Exception - if the search can't be completed

rankedAttributes

public double[][] rankedAttributes()
                            throws java.lang.Exception

Sorts the evaluated attribute list

Specified by:

rankedAttributes in interface RankedOutputSearch

Returns:

an array of sorted (highest eval to lowest) attribute indexes

Throws:

java.lang.Exception - of sorting can't be done.

toString

public java.lang.String toString()

returns a description of the search as a String

Overrides:

toString in class java.lang.Object

Returns:

a description of the search