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## weka.attributeSelection
Class GainRatioAttributeEval

    java.lang.Object
      weka.attributeSelection.ASEvaluation
          weka.attributeSelection.GainRatioAttributeEval

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

    public class GainRatioAttributeEval

extends ASEvaluation
implements AttributeEvaluator, OptionHandler

GainRatioAttributeEval :
Evaluates the worth of an attribute by measuring the gain ratio with respect to the class.
GainR(Class, Attribute) = (H(Class) - H(Class | Attribute)) / H(Attribute).

Valid options are:

     -M
      treat missing values as a seperate value.

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

Constructor Summary
`GainRatioAttributeEval()` Constructor

Method Summary
`void` | `buildEvaluator(Instances data)` Initializes a gain ratio attribute evaluator.
`double` | `evaluateAttribute(int attribute)` evaluates an individual attribute by measuring the gain ratio of the class given the attribute.
`Capabilities` | `getCapabilities()` Returns the capabilities of this evaluator.
`boolean` | `getMissingMerge()` get whether missing values are being distributed or not
`java.lang.String[]` | `getOptions()` Gets the current settings of WrapperSubsetEval.
`java.lang.String` | `getRevision()` Returns the revision string.
`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.
`java.lang.String` | `missingMergeTipText()` Returns the tip text for this property
`void` | `setMissingMerge(boolean b)` distribute the counts for missing values across observed values
`void` | `setOptions(java.lang.String[] options)` Parses a given list of options.
`java.lang.String` | `toString()` Return a description of the evaluator

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

### GainRatioAttributeEval

    public GainRatioAttributeEval()

  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

### 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
        treat missing values as a seperate value.

  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

### missingMergeTipText

    public java.lang.String missingMergeTipText()

  Returns the tip text for this property

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

### setMissingMerge

    public void setMissingMerge(boolean b)

  distribute the counts for missing values across observed values

  Parameters:
    `b` - true=distribute missing values.

### getMissingMerge

    public boolean getMissingMerge()

  get whether missing values are being distributed or not

  Returns:
    true if missing values are being distributed.

### getOptions

    public java.lang.String[] getOptions()

  Gets the current settings of WrapperSubsetEval.

  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

  Initializes a gain ratio attribute evaluator. Discretizes all attributes that are numeric.

  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 by measuring the gain ratio of the class given the attribute.

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

### toString

    public java.lang.String toString()

  Return a description of the evaluator

  Overrides:
    `toString` in class `java.lang.Object`
  Returns:
    description as a string

### 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.

  Parameters:
    `args` - the options -t training file

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