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Class weka.attributeSelection.BestFirst

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

public class BestFirst

extends ASSearch

implements OptionHandler, StartSetHandler

Valid options are:

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

-D <-1 = backward | 0 = bidirectional | 1 = forward>
Direction of the search. (default = 1).

-N
Number of non improving nodes to consider before terminating search. (default = 5).

Version:

$Revision: 1.12 $

Author:

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

TAGS_SELECTION

BestFirst()

Constructor

getDirection()

Get the search direction

getOptions()

Gets the current settings of BestFirst.

getSearchTermination()

Get the termination criterion (number of non-improving nodes).

getStartSet()

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

listOptions()

Returns an enumeration describing the available options

search(ASEvaluation, Instances)

Searches the attribute subset space by best first search

setDirection(SelectedTag)

Set the search direction

setOptions(String[])

Parses a given list of options.

setSearchTermination(int)

Set the numnber of non-improving nodes to consider before terminating search.

setStartSet(String)

Sets a starting set of attributes for the search.

toString()

returns a description of the search as a String

 public static final Tag TAGS_SELECTION[]

 public BestFirst()

Constructor

 public Enumeration listOptions()

Returns an enumeration describing the available options

Returns:

an enumeration of all the available options

 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.

-D <-1 = backward | 0 = bidirectional | 1 = forward>
Direction of the search. (default = 1).

-N
Number of non improving nodes to consider before terminating search. (default = 5).

Parameters:

options - the list of options as an array of strings

Throws: Exception

if an option is not supported

 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: if

start set can't be set.

 public String getStartSet()

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

Returns:

a list of attributes (and or attribute ranges)

 public void setSearchTermination(int t) throws Exception

Set the numnber of non-improving nodes to consider before terminating search.

Parameters:

t - the number of non-improving nodes

Throws: Exception

if t is less than 1

 public int getSearchTermination()

Get the termination criterion (number of non-improving nodes).

Returns:

the number of non-improving nodes

 public void setDirection(SelectedTag d)

Set the search direction

Parameters:

d - the direction of the search

 public SelectedTag getDirection()

Get the search direction

Returns:

the direction of the search

 public String[] getOptions()

Gets the current settings of BestFirst.

Returns:

an array of strings suitable for passing to setOptions()

 public String toString()

returns a description of the search as a String

Returns:

a description of the search

Overrides:

toString in class Object

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

Searches the attribute subset space by best first search

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

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