GreedyStepwise

java.lang.Object
- weka.attributeSelection.ASSearch
- - weka.attributeSelection.GreedyStepwise

All Implemented Interfaces:: java.io.Serializable, RankedOutputSearch, StartSetHandler, OptionHandler, RevisionHandler

public class GreedyStepwise
extends ASSearch
implements RankedOutputSearch, StartSetHandler, OptionHandler

GreedyStepwise :

Performs a greedy forward or backward search through the space of attribute subsets. May start with no/all attributes or from an arbitrary point in the space. Stops when the addition/deletion of any remaining attributes results in a decrease in evaluation. Can also produce a ranked list of attributes by traversing the space from one side to the other and recording the order that attributes are selected.

Valid options are:

 -C
  Use conservative forward search

 -B
  Use a backward search instead of a
  forward one.

 -P <start set>
  Specify a starting set of attributes.
  Eg. 1,3,5-7.

 -R
  Produce a ranked list of attributes.

 -T <threshold>
  Specify a theshold by which attributes
  may be discarded from the ranking.
  Use in conjuction with -R

 -N <num to select>
  Specify number of attributes to select

 -num-slots <int>
  The number of execution slots, for example, the number of cores in the CPU. (default 1)

 -D
  Print debugging output

Version:: $Revision: 15520 $
Author:: Mark Hall
See Also:: Serialized Form

Constructor Summary

Constructors
Constructor and Description

GreedyStepwise()
Constructor

Constructors
Constructor and Description
`GreedyStepwise()` Constructor

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`java.lang.String`	`conservativeForwardSelectionTipText()` Returns the tip text for this property
`java.lang.String`	`debuggingOutputTipText()` Returns the tip text for this property
`java.lang.String`	`generateRankingTipText()` Returns the tip text for this property
`int`	`getCalculatedNumToSelect()` Gets the calculated number of attributes to retain.
`boolean`	`getConservativeForwardSelection()` Gets whether conservative selection has been enabled
`boolean`	`getDebuggingOutput()` Get whether to output debugging info to the console
`boolean`	`getGenerateRanking()` Gets whether ranking has been requested.
`int`	`getNumExecutionSlots()` Gets the number of threads.
`int`	`getNumToSelect()` Gets the number of attributes to be retained.
`java.lang.String[]`	`getOptions()` Gets the current settings of ReliefFAttributeEval.
`java.lang.String`	`getRevision()` Returns the revision string.
`boolean`	`getSearchBackwards()` Get whether to search backwards
`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<Option>`	`listOptions()` Returns an enumeration describing the available options.
`java.lang.String`	`numExecutionSlotsTipText()`
`java.lang.String`	`numToSelectTipText()` Returns the tip text for this property
`double[][]`	`rankedAttributes()` Produces a ranked list of attributes.
`int[]`	`search(ASEvaluation ASEval, Instances data)` Searches the attribute subset space by forward selection.
`java.lang.String`	`searchBackwardsTipText()` Returns the tip text for this property
`void`	`setConservativeForwardSelection(boolean c)` Set whether attributes should continue to be added during a forward search as long as merit does not decrease
`void`	`setDebuggingOutput(boolean d)` Set whether to output debugging info to the console
`void`	`setGenerateRanking(boolean doRank)` Records whether the user has requested a ranked list of attributes.
`void`	`setNumExecutionSlots(int nT)` Sets the number of threads
`void`	`setNumToSelect(int n)` Specify the number of attributes to select from the ranked list (if generating a ranking).
`void`	`setOptions(java.lang.String[] options)` Parses a given list of options.
`void`	`setSearchBackwards(boolean back)` Set whether to search backwards instead of forwards
`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.

Methods inherited from class weka.attributeSelection.ASSearch
forName, makeCopies

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface weka.core.OptionHandler
makeCopy

- Constructor Detail
  - GreedyStepwise
```
public GreedyStepwise()
```
    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
  - searchBackwardsTipText
```
public java.lang.String searchBackwardsTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setSearchBackwards
```
public void setSearchBackwards(boolean back)
```
    Set whether to search backwards instead of forwards
    
    Parameters:
    
    back - true to search backwards
  - getSearchBackwards
```
public boolean getSearchBackwards()
```
    Get whether to search backwards
    
    Returns:
    
    true if the search will proceed backwards
  - 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
  - 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 (if generating a ranking). -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 of attributes to retain. This is the actual number of attributes to retain. This is the same as getNumToSelect if the user specifies a number which is not less than zero. Otherwise it should be the number of attributes in the (potentially transformed) data.
    
    Specified by:
    
    getCalculatedNumToSelect in interface RankedOutputSearch
  - 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)
```
    Records whether the user has requested a ranked list of attributes.
    
    Specified by:
    
    setGenerateRanking in interface RankedOutputSearch
    
    Parameters:
    
    doRank - true if ranking is requested
  - getGenerateRanking
```
public boolean getGenerateRanking()
```
    Gets whether ranking has been requested. This is used by the AttributeSelection module to determine if rankedAttributes() should be called.
    
    Specified by:
    
    getGenerateRanking in interface RankedOutputSearch
    
    Returns:
    
    true if ranking has been requested.
  - 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)
  - conservativeForwardSelectionTipText
```
public java.lang.String conservativeForwardSelectionTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setConservativeForwardSelection
```
public void setConservativeForwardSelection(boolean c)
```
    Set whether attributes should continue to be added during a forward search as long as merit does not decrease
    
    Parameters:
    
    c - true if atts should continue to be atted
  - getConservativeForwardSelection
```
public boolean getConservativeForwardSelection()
```
    Gets whether conservative selection has been enabled
    
    Returns:
    
    true if conservative forward selection is enabled
  - debuggingOutputTipText
```
public java.lang.String debuggingOutputTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setDebuggingOutput
```
public void setDebuggingOutput(boolean d)
```
    Set whether to output debugging info to the console
    
    Parameters:
    
    d - true if dubugging info is to be output
  - getDebuggingOutput
```
public boolean getDebuggingOutput()
```
    Get whether to output debugging info to the console
    
    Returns:
    
    true if dubugging info is to be output
  - numExecutionSlotsTipText
```
public java.lang.String numExecutionSlotsTipText()
```
    Returns:
    
    a string to describe the option
  - getNumExecutionSlots
```
public int getNumExecutionSlots()
```
    Gets the number of threads.
  - setNumExecutionSlots
```
public void setNumExecutionSlots(int nT)
```
    Sets the number of threads
  - listOptions
```
public java.util.Enumeration<Option> listOptions()
```
    Returns an enumeration describing the available options.
    
    Specified by:
    
    listOptions in interface OptionHandler
    
    Overrides:
    
    listOptions in class ASSearch
    
    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:
```
 -C
  Use conservative forward search
 
```
```
 -B
  Use a backward search instead of a
  forward one.
 
```
```
 -P <start set>
  Specify a starting set of attributes.
  Eg. 1,3,5-7.
 
```
```
 -R
  Produce a ranked list of attributes.
 
```
```
 -T <threshold>
  Specify a theshold by which attributes
  may be discarded from the ranking.
  Use in conjuction with -R
 
```
```
 -N <num to select>
  Specify number of attributes to select
 
```
```
 -num-slots <int>
  The number of execution slots, for example, the number of cores in the CPU. (default 1)
 
```
```
 -D
  Print debugging output
 
```
    Specified by:
    
    setOptions in interface OptionHandler
    
    Overrides:
    
    setOptions in class ASSearch
    
    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
    
    Overrides:
    
    getOptions in class ASSearch
    
    Returns:
    
    an array of strings suitable for passing to setOptions()
  - toString
```
public java.lang.String toString()
```
    returns a description of the search.
    
    Overrides:
    
    toString in class java.lang.Object
    
    Returns:
    
    a description of the search as a String.
  - search
```
public int[] search(ASEvaluation ASEval,
                    Instances data)
             throws java.lang.Exception
```
    Searches the attribute subset space by forward selection.
    
    Specified by:
    
    search in class ASSearch
    
    Parameters:
    
    ASEval - 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
  - rankedAttributes
```
public double[][] rankedAttributes()
                            throws java.lang.Exception
```
    Produces a ranked list of attributes. Search must have been performed prior to calling this function. Search is called by this function to complete the traversal of the the search space. A list of attributes and merits are returned. The attributes a ranked by the order they are added to the subset during a forward selection search. Individual merit values reflect the merit associated with adding the corresponding attribute to the subset; because of this, merit values may initially increase but then decrease as the best subset is "passed by" on the way to the far side of the search space.
    
    Specified by:
    
    rankedAttributes in interface RankedOutputSearch
    
    Returns:
    
    an array of attribute indexes and associated merit values
    
    Throws:
    
    java.lang.Exception - if something goes wrong.
  - getRevision
```
public java.lang.String getRevision()
```
    Returns the revision string.
    
    Specified by:
    
    getRevision in interface RevisionHandler
    
    Overrides:
    
    getRevision in class ASSearch
    
    Returns:
    
    the revision

Class GreedyStepwise

Constructor Summary

Method Summary

Methods inherited from class weka.attributeSelection.ASSearch

Methods inherited from class java.lang.Object

Methods inherited from interface weka.core.OptionHandler

Constructor Detail

GreedyStepwise

Method Detail

globalInfo

searchBackwardsTipText

setSearchBackwards

getSearchBackwards

thresholdTipText

setThreshold

getThreshold

numToSelectTipText

setNumToSelect

getNumToSelect

getCalculatedNumToSelect

generateRankingTipText

setGenerateRanking

getGenerateRanking

startSetTipText

setStartSet

getStartSet

conservativeForwardSelectionTipText

setConservativeForwardSelection

getConservativeForwardSelection

debuggingOutputTipText

setDebuggingOutput

getDebuggingOutput

numExecutionSlotsTipText

getNumExecutionSlots

setNumExecutionSlots

listOptions

setOptions

getOptions

toString

search

rankedAttributes

getRevision