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## weka.attributeSelection
Class ReliefFAttributeEval

    java.lang.Object
      weka.attributeSelection.ASEvaluation
          weka.attributeSelection.ReliefFAttributeEval

All Implemented Interfaces:
  java.io.Serializable, AttributeEvaluator, CapabilitiesHandler, OptionHandler, RevisionHandler, TechnicalInformationHandler

    public class ReliefFAttributeEval

extends ASEvaluation
implements AttributeEvaluator, OptionHandler, TechnicalInformationHandler

ReliefFAttributeEval :
Evaluates the worth of an attribute by repeatedly sampling an instance and considering the value of the given attribute for the nearest instance of the same and different class. Can operate on both discrete and continuous class data.
For more information see:
Kenji Kira, Larry A. Rendell: A Practical Approach to Feature Selection. In: Ninth International Workshop on Machine Learning, 249-256, 1992.
Igor Kononenko: Estimating Attributes: Analysis and Extensions of RELIEF. In: European Conference on Machine Learning, 171-182, 1994.
Marko Robnik-Sikonja, Igor Kononenko: An adaptation of Relief for attribute estimation in regression. In: Fourteenth International Conference on Machine Learning, 296-304, 1997.

BibTeX:

     @inproceedings{Kira1992,
        author = {Kenji Kira and Larry A. Rendell},
        booktitle = {Ninth International Workshop on Machine Learning},
        editor = {Derek H. Sleeman and Peter Edwards},
        pages = {249-256},
        publisher = {Morgan Kaufmann},
        title = {A Practical Approach to Feature Selection},
        year = {1992}
     }

     @inproceedings{Kononenko1994,
        author = {Igor Kononenko},
        booktitle = {European Conference on Machine Learning},
        editor = {Francesco Bergadano and Luc De Raedt},
        pages = {171-182},
        publisher = {Springer},
        title = {Estimating Attributes: Analysis and Extensions of RELIEF},
        year = {1994}
     }

     @inproceedings{Robnik-Sikonja1997,
        author = {Marko Robnik-Sikonja and Igor Kononenko},
        booktitle = {Fourteenth International Conference on Machine Learning},
        editor = {Douglas H. Fisher},
        pages = {296-304},
        publisher = {Morgan Kaufmann},
        title = {An adaptation of Relief for attribute estimation in regression},
        year = {1997}
     }

Valid options are:

     -M <num instances>
      Specify the number of instances to
      sample when estimating attributes.
      If not specified, then all instances
      will be used.

     -D <seed>
      Seed for randomly sampling instances.
      (Default = 1)

     -K <number of neighbours>
      Number of nearest neighbours (k) used
      to estimate attribute relevances
      (Default = 10).

     -W
      Weight nearest neighbours by distance

     -A <num>
      Specify sigma value (used in an exp
      function to control how quickly
      weights for more distant instances
      decrease. Use in conjunction with -W.
      Sensible value=1/5 to 1/10 of the
      number of nearest neighbours.
      (Default = 2)

Version:
  $Revision: 5511 $
Author:
  Mark Hall (mhall@cs.waikato.ac.nz)
See Also:
  Serialized Form

Constructor Summary
`ReliefFAttributeEval()` Constructor

Method Summary
`void` | `buildEvaluator(Instances data)` Initializes a ReliefF attribute evaluator.
`double` | `evaluateAttribute(int attribute)` Evaluates an individual attribute using ReliefF's instance based approach.
`Capabilities` | `getCapabilities()` Returns the capabilities of this evaluator.
`int` | `getNumNeighbours()` Get the number of nearest neighbours
`java.lang.String[]` | `getOptions()` Gets the current settings of ReliefFAttributeEval.
`java.lang.String` | `getRevision()` Returns the revision string.
`int` | `getSampleSize()` Get the number of instances used for estimating attributes
`int` | `getSeed()` Get the seed used for randomly sampling instances.
`int` | `getSigma()` Get the value of sigma.
`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.
`boolean` | `getWeightByDistance()` Get whether nearest neighbours are being weighted by distance
`java.lang.String` | `globalInfo()` Returns a string describing this attribute evaluator
`java.util.Enumeration` | `listOptions()` Returns an enumeration describing the available options.
`static void` | `main(java.lang.String[] args)` Main method for testing this class.
`java.lang.String` | `numNeighboursTipText()` Returns the tip text for this property
`java.lang.String` | `sampleSizeTipText()` Returns the tip text for this property
`java.lang.String` | `seedTipText()` Returns the tip text for this property
`void` | `setNumNeighbours(int n)` Set the number of nearest neighbours
`void` | `setOptions(java.lang.String[] options)` Parses a given list of options.
`void` | `setSampleSize(int s)` Set the number of instances to sample for attribute estimation
`void` | `setSeed(int s)` Set the random number seed for randomly sampling instances.
`void` | `setSigma(int s)` Sets the sigma value.
`void` | `setWeightByDistance(boolean b)` Set the nearest neighbour weighting method
`java.lang.String` | `sigmaTipText()` Returns the tip text for this property
`java.lang.String` | `toString()` Return a description of the ReliefF attribute evaluator.
`java.lang.String` | `weightByDistanceTipText()` Returns the tip text for this property

Methods inherited from class weka.attributeSelection.ASEvaluation
`forName, makeCopies, postProcess`

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

Constructor Detail

### ReliefFAttributeEval

    public ReliefFAttributeEval()

  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 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:

       -M <num instances>
        Specify the number of instances to
        sample when estimating attributes.
        If not specified, then all instances
        will be used.

       -D <seed>
        Seed for randomly sampling instances.
        (Default = 1)

       -K <number of neighbours>
        Number of nearest neighbours (k) used
        to estimate attribute relevances
        (Default = 10).

       -W
        Weight nearest neighbours by distance

       -A <num>
        Specify sigma value (used in an exp
        function to control how quickly
        weights for more distant instances
        decrease. Use in conjunction with -W.
        Sensible value=1/5 to 1/10 of the
        number of nearest neighbours.
        (Default = 2)

  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

### sigmaTipText

    public java.lang.String sigmaTipText()

  Returns the tip text for this property

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

### setSigma

    public void setSigma(int s)
                  throws java.lang.Exception

  Sets the sigma value.

  Parameters:
    `s` - the value of sigma (> 0)
  Throws:
    `java.lang.Exception` - if s is not positive

### getSigma

    public int getSigma()

  Get the value of sigma.

  Returns:
    the sigma value.

### numNeighboursTipText

    public java.lang.String numNeighboursTipText()

  Returns the tip text for this property

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

### setNumNeighbours

    public void setNumNeighbours(int n)

  Set the number of nearest neighbours

  Parameters:
    `n` - the number of nearest neighbours.

### getNumNeighbours

    public int getNumNeighbours()

  Get the number of nearest neighbours

  Returns:
    the number of nearest neighbours

### seedTipText

    public java.lang.String seedTipText()

  Returns the tip text for this property

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

### setSeed

    public void setSeed(int s)

  Set the random number seed for randomly sampling instances.

  Parameters:
    `s` - the random number seed.

### getSeed

    public int getSeed()

  Get the seed used for randomly sampling instances.

  Returns:
    the random number seed.

### sampleSizeTipText

    public java.lang.String sampleSizeTipText()

  Returns the tip text for this property

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

### setSampleSize

    public void setSampleSize(int s)

  Set the number of instances to sample for attribute estimation

  Parameters:
    `s` - the number of instances to sample.

### getSampleSize

    public int getSampleSize()

  Get the number of instances used for estimating attributes

  Returns:
    the number of instances.

### weightByDistanceTipText

    public java.lang.String weightByDistanceTipText()

  Returns the tip text for this property

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

### setWeightByDistance

    public void setWeightByDistance(boolean b)

  Set the nearest neighbour weighting method

  Parameters:
    `b` - true nearest neighbours are to be weighted by distance.

### getWeightByDistance

    public boolean getWeightByDistance()

  Get whether nearest neighbours are being weighted by distance

  Returns:
    m_weightByDiffernce

### getOptions

    public java.lang.String[] getOptions()

  Gets the current settings of ReliefFAttributeEval.

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

### toString

    public java.lang.String toString()

  Return a description of the ReliefF attribute evaluator.

  Overrides:
    `toString` in class `java.lang.Object`
  Returns:
    a description of the evaluator as a String.

### 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

  Initializes a ReliefF attribute evaluator.

  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

### evaluateAttribute

    public double evaluateAttribute(int attribute)
                             throws java.lang.Exception

  Evaluates an individual attribute using ReliefF's instance based approach. The actual work is done by buildEvaluator which evaluates all features.

  Specified by:
    `evaluateAttribute` in interface `AttributeEvaluator`
  Parameters:
    `attribute` - the index of the attribute to be evaluated
  Returns:
    the "merit" of the attribute
  Throws:
    `java.lang.Exception` - if the attribute could not be evaluated

### 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

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