weka.attributeSelection

## Class CfsSubsetEval

- java.lang.Object
- - weka.attributeSelection.ASEvaluation
  - - weka.attributeSelection.CfsSubsetEval

- All Implemented Interfaces:
    java.io.Serializable, SubsetEvaluator, CapabilitiesHandler, CapabilitiesIgnorer, OptionHandler, RevisionHandler, TechnicalInformationHandler, ThreadSafe

      public class CfsSubsetEval
      extends ASEvaluation
      implements SubsetEvaluator, ThreadSafe, OptionHandler, TechnicalInformationHandler

  CfsSubsetEval :
  Evaluates the worth of a subset of attributes by considering the individual predictive ability of each feature along with the degree of redundancy between them.
  Subsets of features that are highly correlated with the class while having low intercorrelation are preferred.
  For more information see:
  M. A. Hall (1998). Correlation-based Feature Subset Selection for Machine Learning. Hamilton, New Zealand.

  BibTeX:

       @phdthesis{Hall1998,
          address = {Hamilton, New Zealand},
          author = {M. A. Hall},
          school = {University of Waikato},
          title = {Correlation-based Feature Subset Selection for Machine Learning},
          year = {1998}
       }

  Valid options are:

       -M
        Treat missing values as a separate value.

       -L
        Don't include locally predictive attributes.

       -Z
        Precompute the full correlation matrix at the outset, rather than compute correlations lazily (as needed) during the search. Use this in conjuction with parallel processing in order to speed up a backward search.

       -P <int>
        The size of the thread pool, for example, the number of cores in the CPU. (default 1)

       -E <int>
        The number of threads to use, which should be >= size of thread pool. (default 1)

       -D
        Output debugging info.

  Version:
    $Revision: 11852 $
  Author:
    Mark Hall (mhall@cs.waikato.ac.nz)
  See Also:
    `Discretize`, Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `CfsSubsetEval()` Constructor

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `buildEvaluator(Instances data)` Generates a attribute evaluator.
    `void` | `clean()` Tells the evaluator that the attribute selection process is complete.
    `java.lang.String` | `debugTipText()` Returns the tip text for this property
    `double` | `evaluateSubset(java.util.BitSet subset)` evaluates a subset of attributes
    `Capabilities` | `getCapabilities()` Returns the capabilities of this evaluator.
    `boolean` | `getDebug()` Set whether to output debugging info
    `boolean` | `getLocallyPredictive()` Return true if including locally predictive attributes
    `boolean` | `getMissingSeparate()` Return true is missing is treated as a separate value
    `int` | `getNumThreads()` Gets the number of threads.
    `java.lang.String[]` | `getOptions()` Gets the current settings of CfsSubsetEval
    `int` | `getPoolSize()` Gets the number of threads.
    `boolean` | `getPreComputeCorrelationMatrix()` Get whether to pre-compute the full correlation matrix at the outset, rather than computing individual correlations lazily (as needed) during the search.
    `java.lang.String` | `getRevision()` Returns the revision 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.
    `java.lang.String` | `globalInfo()` Returns a string describing this attribute evaluator
    `java.util.Enumeration<Option>` | `listOptions()` Returns an enumeration describing the available options.
    `java.lang.String` | `locallyPredictiveTipText()` Returns the tip text for this property
    `static void` | `main(java.lang.String[] args)` Main method for testing this class.
    `java.lang.String` | `missingSeparateTipText()` Returns the tip text for this property
    `java.lang.String` | `numThreadsTipText()`
    `java.lang.String` | `poolSizeTipText()`
    `int[]` | `postProcess(int[] attributeSet)` Calls locallyPredictive in order to include locally predictive attributes (if requested).
    `java.lang.String` | `preComputeCorrelationMatrixTipText()`
    `void` | `setDebug(boolean d)` Set whether to output debugging info
    `void` | `setLocallyPredictive(boolean b)` Include locally predictive attributes
    `void` | `setMissingSeparate(boolean b)` Treat missing as a separate value
    `void` | `setNumThreads(int nT)` Sets the number of threads
    `void` | `setOptions(java.lang.String[] options)` Parses and sets a given list of options.
    `void` | `setPoolSize(int nT)` Sets the number of threads
    `void` | `setPreComputeCorrelationMatrix(boolean p)` Set whether to pre-compute the full correlation matrix at the outset, rather than computing individual correlations lazily (as needed) during the search.
    `java.lang.String` | `toString()` returns a string describing CFS

    - ### Methods inherited from class weka.attributeSelection.ASEvaluation

      `doNotCheckCapabilitiesTipText, forName, getDoNotCheckCapabilities, makeCopies, runEvaluator, setDoNotCheckCapabilities`

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### CfsSubsetEval

          public CfsSubsetEval()

      Constructor

  - ### Method Detail

    - #### globalInfo

          public java.lang.String globalInfo()

      Returns a string describing this attribute evaluator
      Returns:
        a description of the evaluator 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<Option> 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 and sets a given list of options.

      Valid options are:

           -M
            Treat missing values as a separate value.

           -L
            Don't include locally predictive attributes.

           -Z
            Precompute the full correlation matrix at the outset, rather than compute correlations lazily (as needed) during the search. Use this in conjuction with parallel processing in order to speed up a backward search.

           -P <int>
            The size of the thread pool, for example, the number of cores in the CPU. (default 1)

           -E <int>
            The number of threads to use, which should be >= size of thread pool. (default 1)

           -D
            Output debugging info.

      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

    - #### preComputeCorrelationMatrixTipText

          public java.lang.String preComputeCorrelationMatrixTipText()

      Returns:
        a string to describe the option

    - #### setPreComputeCorrelationMatrix

          public void setPreComputeCorrelationMatrix(boolean p)

      Set whether to pre-compute the full correlation matrix at the outset, rather than computing individual correlations lazily (as needed) during the search.
      Parameters:
        `p` - true if the correlation matrix is to be pre-computed at the outset

    - #### getPreComputeCorrelationMatrix

          public boolean getPreComputeCorrelationMatrix()

      Get whether to pre-compute the full correlation matrix at the outset, rather than computing individual correlations lazily (as needed) during the search.
      Returns:
        true if the correlation matrix is to be pre-computed at the outset

    - #### numThreadsTipText

          public java.lang.String numThreadsTipText()

      Returns:
        a string to describe the option

    - #### getNumThreads

          public int getNumThreads()

      Gets the number of threads.

    - #### setNumThreads

          public void setNumThreads(int nT)

      Sets the number of threads

    - #### poolSizeTipText

          public java.lang.String poolSizeTipText()

      Returns:
        a string to describe the option

    - #### getPoolSize

          public int getPoolSize()

      Gets the number of threads.

    - #### setPoolSize

          public void setPoolSize(int nT)

      Sets the number of threads

    - #### locallyPredictiveTipText

          public java.lang.String locallyPredictiveTipText()

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

    - #### setLocallyPredictive

          public void setLocallyPredictive(boolean b)

      Include locally predictive attributes
      Parameters:
        `b` - true or false

    - #### getLocallyPredictive

          public boolean getLocallyPredictive()

      Return true if including locally predictive attributes
      Returns:
        true if locally predictive attributes are to be used

    - #### missingSeparateTipText

          public java.lang.String missingSeparateTipText()

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

    - #### setMissingSeparate

          public void setMissingSeparate(boolean b)

      Treat missing as a separate value
      Parameters:
        `b` - true or false

    - #### getMissingSeparate

          public boolean getMissingSeparate()

      Return true is missing is treated as a separate value
      Returns:
        true if missing is to be treated as a separate value

    - #### setDebug

          public void setDebug(boolean d)

      Set whether to output debugging info
      Parameters:
        `d` - true if debugging info is to be output

    - #### getDebug

          public boolean getDebug()

      Set whether to output debugging info
      Returns:
        true if debugging info is to be output

    - #### debugTipText

          public java.lang.String debugTipText()

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

    - #### getOptions

          public java.lang.String[] getOptions()

      Gets the current settings of CfsSubsetEval
      Specified by:
        `getOptions` in interface `OptionHandler`
      Returns:
        an array of strings suitable for passing to setOptions()

    - #### getCapabilities

          public Capabilities getCapabilities()

      Returns the capabilities of this evaluator.
      Specified by:
        `getCapabilities` in interface `CapabilitiesHandler`
      Overrides:
        `getCapabilities` in class `ASEvaluation`
      Returns:
        the capabilities of this evaluator
      See Also:
        `Capabilities`

    - #### buildEvaluator

          public void buildEvaluator(Instances data)
                              throws java.lang.Exception

      Generates a attribute evaluator. Has to initialize all fields of the evaluator that are not being set via options. CFS also discretises attributes (if necessary) and initializes the correlation matrix.
      Specified by:
        `buildEvaluator` in class `ASEvaluation`
      Parameters:
        `data` - set of instances serving as training data
      Throws:
        `java.lang.Exception` - if the evaluator has not been generated successfully

    - #### evaluateSubset

          public double evaluateSubset(java.util.BitSet subset)
                                throws java.lang.Exception

      evaluates a subset of attributes
      Specified by:
        `evaluateSubset` in interface `SubsetEvaluator`
      Parameters:
        `subset` - a bitset representing the attribute subset to be evaluated
      Returns:
        the merit
      Throws:
        `java.lang.Exception` - if the subset could not be evaluated

    - #### toString

          public java.lang.String toString()

      returns a string describing CFS
      Overrides:
        `toString` in class `java.lang.Object`
      Returns:
        the description as a string

    - #### postProcess

          public int[] postProcess(int[] attributeSet)
                            throws java.lang.Exception

      Calls locallyPredictive in order to include locally predictive attributes (if requested).
      Overrides:
        `postProcess` in class `ASEvaluation`
      Parameters:
        `attributeSet` - the set of attributes found by the search
      Returns:
        a possibly ranked list of postprocessed attributes
      Throws:
        `java.lang.Exception` - if postprocessing fails for some reason

    - #### clean

          public void clean()

      Description copied from class: `ASEvaluation`
      Tells the evaluator that the attribute selection process is complete. It can then clean up data structures, references to training data as necessary in order to save memory
      Overrides:
        `clean` in class `ASEvaluation`

    - #### getRevision

          public java.lang.String getRevision()

      Returns the revision string.
      Specified by:
        `getRevision` in interface `RevisionHandler`
      Overrides:
        `getRevision` in class `ASEvaluation`
      Returns:
        the revision

    - #### main

          public static void main(java.lang.String[] args)

      Main method for testing this class.
      Parameters:
        `args` - the options