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Class weka.attributeSelection.Ranker 

java.lang.Object
   |
   +----weka.attributeSelection.ASSearch
           |
           +----weka.attributeSelection.Ranker
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: 1.9 $
Author:
Mark Hall (mhall@cs.waikato.ac.nz)

Constructor Index

o Ranker()
Constructor

Method Index

o getGenerateRanking()
This is a dummy method.
o getOptions()
Gets the current settings of ReliefFAttributeEval.
o getStartSet()
Returns a list of attributes (and or attribute ranges) as a String
o getThreshold()
Returns the threshold so that the AttributeSelection module can discard attributes from the ranking.
o listOptions()
Returns an enumeration describing the available options
o rankedAttributes()
Sorts the evaluated attribute list
o search(ASEvaluation, Instances)
Kind of a dummy search algorithm.
o setGenerateRanking(boolean)
This is a dummy set method---Ranker is ONLY capable of producing a ranked list of attributes for attribute evaluators.
o setOptions(String[])
Parses a given list of options.
o setStartSet(String)
Sets a starting set of attributes for the search.
o setThreshold(double)
Set the threshold by which the AttributeSelection module can discard attributes.
o toString()
returns a description of the search as a String

Constructors

o Ranker 
 public Ranker()
Constructor

Methods

o setThreshold 
 public void setThreshold(double threshold)
Set the threshold by which the AttributeSelection module can discard attributes.

Parameters:
threshold - the threshold.
o getThreshold 
 public double getThreshold()
Returns the threshold so that the AttributeSelection module can discard attributes from the ranking.

o 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.

Parameters:
doRank - this parameter is N/A and is ignored
o 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

Returns:
true all the time.
o setStartSet 
 public void setStartSet(String startSet) throws 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.

Parameters:
startSet - a string containing a list of attributes (and or ranges), eg. 1,2,6,10-15.
Throws: Exception
if start set can't be set.
o getStartSet 
 public String getStartSet()
Returns a list of attributes (and or attribute ranges) as a String

Returns:
a list of attributes (and or attribute ranges)
o listOptions 
 public Enumeration listOptions()
Returns an enumeration describing the available options

Returns:
an enumeration of all the available options
o setOptions 
 public void setOptions(String options[]) throws 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.

Parameters:
options - the list of options as an array of strings
Throws: Exception
if an option is not supported
o getOptions 
 public String[] getOptions()
Gets the current settings of ReliefFAttributeEval.

Returns:
an array of strings suitable for passing to setOptions()
o search 
 public int[] search(ASEvaluation ASEval,
                     Instances data) throws 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.

Parameters:
ASEvaluator - the attribute evaluator to guide the search
data - the training instances.
Returns:
an array (not necessarily ordered) of selected attribute indexes
Throws: Exception
if the search can't be completed
Overrides:
search in class ASSearch
o rankedAttributes 
 public double[][] rankedAttributes() throws Exception
Sorts the evaluated attribute list

Returns:
an array of sorted (highest eval to lowest) attribute indexes
Throws: Exception
of sorting can't be done.
o toString 
 public String toString()
returns a description of the search as a String

Returns:
a description of the search
Overrides:
toString in class Object 
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