weka.attributeSelection
Class LinearForwardSelection

java.lang.Object
  extended by weka.attributeSelection.ASSearch
      extended by weka.attributeSelection.LinearForwardSelection
All Implemented Interfaces:
java.io.Serializable, StartSetHandler, OptionHandler, RevisionHandler, TechnicalInformationHandler

public class LinearForwardSelection
extends ASSearch
implements OptionHandler, StartSetHandler, TechnicalInformationHandler

LinearForwardSelection:

Extension of BestFirst. Takes a restricted number of k attributes into account. Fixed-set selects a fixed number k of attributes, whereas k is increased in each step when fixed-width is selected. The search uses either the initial ordering to select the top k attributes, or performs a ranking (with the same evalutator the search uses later on). The search direction can be forward, or floating forward selection (with opitional backward search steps).

For more information see:

Martin Guetlein (2006). Large Scale Attribute Selection Using Wrappers. Freiburg, Germany.

Valid options are:

 -P <start set>
  Specify a starting set of attributes.
  Eg. 1,3,5-7.
 -D <0 = forward selection | 1 = floating forward selection>
  Forward selection method. (default = 0).
 -N <num>
  Number of non-improving nodes to
  consider before terminating search.
 -I
  Perform initial ranking to select the
  top-ranked attributes.
 -K <num>
  Number of top-ranked attributes that are 
  taken into account by the search.
 -T <0 = fixed-set | 1 = fixed-width>
  Type of Linear Forward Selection (default = 0).
 -S <num>
  Size of lookup cache for evaluated subsets.
  Expressed as a multiple of the number of
  attributes in the data set. (default = 1)
 -Z
  verbose on/off

Version:
$Revision: 6161 $
Author:
Martin Guetlein (martin.guetlein@gmail.com)
See Also:
Serialized Form

Field Summary
static Tag[] TAGS_SEARCH_METHOD
           
static Tag[] TAGS_TYPE
           
 
Constructor Summary
LinearForwardSelection()
          Constructor
 
Method Summary
 java.lang.String forwardSelectionMethodTipText()
          Returns the tip text for this property
 SelectedTag getForwardSelectionMethod()
          Get the search direction
 int getLookupCacheSize()
          Return the maximum size of the evaluated subset cache (expressed as a multiplier for the number of attributes in a data set.
 int getNumUsedAttributes()
          Get the number of top-ranked attributes that taken into account by the search process.
 java.lang.String[] getOptions()
          Gets the current settings of LinearForwardSelection.
 boolean getPerformRanking()
          Get boolean if initial ranking should be performed to select the top-ranked attributes
 java.lang.String getRevision()
          Returns the revision string.
 int getSearchTermination()
          Get the termination criterion (number of non-improving nodes).
 java.lang.String getStartSet()
          Returns a list of attributes (and or attribute ranges) as a String
 TechnicalInformation getTechnicalInformation()
          Returns an instance of a TechnicalInformation object, containing detailed information about the technical background of this class, e.g., paper reference or book this class is based on.
 SelectedTag getType()
          Get the type
 boolean getVerbose()
          Get whether output is to be verbose
 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 lookupCacheSizeTipText()
          Returns the tip text for this property
 java.lang.String numUsedAttributesTipText()
          Returns the tip text for this property
 java.lang.String performRankingTipText()
          Returns the tip text for this property
 int[] search(ASEvaluation ASEval, Instances data)
          Searches the attribute subset space by linear forward selection
 java.lang.String searchTerminationTipText()
          Returns the tip text for this property
 void setForwardSelectionMethod(SelectedTag d)
          Set the search direction
 void setLookupCacheSize(int size)
          Set the maximum size of the evaluated subset cache (hashtable).
 void setNumUsedAttributes(int k)
          Set the number of top-ranked attributes that taken into account by the search process.
 void setOptions(java.lang.String[] options)
          Parses a given list of options.
 void setPerformRanking(boolean b)
          Perform initial ranking to select top-ranked attributes.
 void setSearchTermination(int t)
          Set the numnber of non-improving nodes to consider before terminating search.
 void setStartSet(java.lang.String startSet)
          Sets a starting set of attributes for the search.
 void setType(SelectedTag t)
          Set the type
 void setVerbose(boolean b)
          Set whether verbose output should be generated.
 java.lang.String startSetTipText()
          Returns the tip text for this property
 java.lang.String toString()
          returns a description of the search as a String
 java.lang.String typeTipText()
          Returns the tip text for this property
 java.lang.String verboseTipText()
          Returns the tip text for this property
 
Methods inherited from class weka.attributeSelection.ASSearch
forName, makeCopies
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

TAGS_SEARCH_METHOD

public static final Tag[] TAGS_SEARCH_METHOD

TAGS_TYPE

public static final Tag[] TAGS_TYPE
Constructor Detail

LinearForwardSelection

public LinearForwardSelection()
Constructor

Method Detail

globalInfo

public java.lang.String globalInfo()
Returns a string describing this search method

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

getTechnicalInformation

public TechnicalInformation getTechnicalInformation()
Returns an instance of a TechnicalInformation object, containing detailed information about the technical background of this class, e.g., paper reference or book this class is based on.

Specified by:
getTechnicalInformation in interface TechnicalInformationHandler
Returns:
the technical information about this class

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.

-D <0 = forward selection | 1 = floating forward selection>
Forward selection method of the search. (default = 0).

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

-I
Perform initial ranking to select top-ranked attributes.

-K
Number of top-ranked attributes that are taken into account.

-T <0 = fixed-set | 1 = fixed-width>
Typ of Linear Forward Selection (default = 0).

-S
Size of lookup cache for evaluated subsets. Expressed as a multiple of the number of attributes in the data set. (default = 1).

-Z
verbose on/off.

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

setLookupCacheSize

public void setLookupCacheSize(int size)
Set the maximum size of the evaluated subset cache (hashtable). This is expressed as a multiplier for the number of attributes in the data set. (default = 1).

Parameters:
size - the maximum size of the hashtable

getLookupCacheSize

public int getLookupCacheSize()
Return the maximum size of the evaluated subset cache (expressed as a multiplier for the number of attributes in a data set.

Returns:
the maximum size of the hashtable.

lookupCacheSizeTipText

public java.lang.String lookupCacheSizeTipText()
Returns the tip text for this property

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

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)

searchTerminationTipText

public java.lang.String searchTerminationTipText()
Returns the tip text for this property

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

setSearchTermination

public void setSearchTermination(int t)
                          throws java.lang.Exception
Set the numnber of non-improving nodes to consider before terminating search.

Parameters:
t - the number of non-improving nodes
Throws:
java.lang.Exception - if t is less than 1

getSearchTermination

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

Returns:
the number of non-improving nodes

performRankingTipText

public java.lang.String performRankingTipText()
Returns the tip text for this property

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

setPerformRanking

public void setPerformRanking(boolean b)
Perform initial ranking to select top-ranked attributes.

Parameters:
b - true if initial ranking should be performed

getPerformRanking

public boolean getPerformRanking()
Get boolean if initial ranking should be performed to select the top-ranked attributes

Returns:
true if initial ranking should be performed

numUsedAttributesTipText

public java.lang.String numUsedAttributesTipText()
Returns the tip text for this property

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

setNumUsedAttributes

public void setNumUsedAttributes(int k)
                          throws java.lang.Exception
Set the number of top-ranked attributes that taken into account by the search process.

Parameters:
k - the number of attributes
Throws:
java.lang.Exception - if k is less than 2

getNumUsedAttributes

public int getNumUsedAttributes()
Get the number of top-ranked attributes that taken into account by the search process.

Returns:
the number of top-ranked attributes that taken into account

forwardSelectionMethodTipText

public java.lang.String forwardSelectionMethodTipText()
Returns the tip text for this property

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

setForwardSelectionMethod

public void setForwardSelectionMethod(SelectedTag d)
Set the search direction

Parameters:
d - the direction of the search

getForwardSelectionMethod

public SelectedTag getForwardSelectionMethod()
Get the search direction

Returns:
the direction of the search

typeTipText

public java.lang.String typeTipText()
Returns the tip text for this property

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

setType

public void setType(SelectedTag t)
Set the type

Parameters:
t - the Linear Forward Selection type

getType

public SelectedTag getType()
Get the type

Returns:
the Linear Forward Selection type

verboseTipText

public java.lang.String verboseTipText()
Returns the tip text for this property

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

setVerbose

public void setVerbose(boolean b)
Set whether verbose output should be generated.

Parameters:
d - true if output is to be verbose.

getVerbose

public boolean getVerbose()
Get whether output is to be verbose

Returns:
true if output will be verbose

getOptions

public java.lang.String[] getOptions()
Gets the current settings of LinearForwardSelection.

Specified by:
getOptions in interface OptionHandler
Returns:
an array of strings suitable for passing to setOptions()

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

search

public int[] search(ASEvaluation ASEval,
                    Instances data)
             throws java.lang.Exception
Searches the attribute subset space by linear forward selection

Specified by:
search in class ASSearch
Parameters:
ASEvaluator - the attribute evaluator to guide the search
data - the training instances.
Returns:
an array (not necessarily ordered) of selected attribute indexes
Throws:
java.lang.Exception - if the search can't be completed

getRevision

public java.lang.String getRevision()
Returns the revision string.

Specified by:
getRevision in interface RevisionHandler
Overrides:
getRevision in class ASSearch
Returns:
the revision