weka.attributeSelection

## Class AttributeSelection

- java.lang.Object
- - weka.attributeSelection.AttributeSelection

- All Implemented Interfaces:
    java.io.Serializable, RevisionHandler

      public class AttributeSelection
      extends java.lang.Object
      implements java.io.Serializable, RevisionHandler

  Attribute selection class. Takes the name of a search class and an evaluation class on the command line.

  Valid options are:

  -h
  Display help.

  -i <name of input file>
  Specify the training data file.

  -c <class index>
  The index of the attribute to use as the class.

  -s <search method>
  The full class name of the search method followed by search method options (if any).
  Eg. -s "weka.attributeSelection.BestFirst -N 10"

  -x <number of folds>
  Perform a cross validation.

  -n <random number seed>
  Specify a random number seed. Use in conjuction with -x. (Default = 1).

  ------------------------------------------------------------------------

  Example usage as the main of an attribute evaluator (called FunkyEvaluator):

       public static void main(String[] args) {
         runEvaluator(new FunkyEvaluator(), args);
       }

  ------------------------------------------------------------------------

  Version:
    $Revision: 10172 $
  Author:
    Mark Hall (mhall@cs.waikato.ac.nz)
  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `AttributeSelection()` constructor.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `java.lang.String` | `CrossValidateAttributes()` Perform a cross validation for attribute selection.
    `java.lang.String` | `CVResultsString()` returns a string summarizing the results of repeated attribute selection runs on splits of a dataset.
    `java.lang.String` | `getRevision()` Returns the revision string.
    `static void` | `main(java.lang.String[] args)` Main method for testing this class.
    `int` | `numberAttributesSelected()` Return the number of attributes selected from the most recent run of attribute selection
    `double[][]` | `rankedAttributes()` get the final ranking of the attributes.
    `Instance` | `reduceDimensionality(Instance in)` reduce the dimensionality of a single instance to include only those attributes chosen by the last run of attribute selection.
    `Instances` | `reduceDimensionality(Instances in)` reduce the dimensionality of a set of instances to include only those attributes chosen by the last run of attribute selection.
    `static java.lang.String` | `SelectAttributes(ASEvaluation ASEvaluator, java.lang.String[] options)` Perform attribute selection with a particular evaluator and a set of options specifying search method and input file etc.
    `static java.lang.String` | `SelectAttributes(ASEvaluation ASEvaluator, java.lang.String[] options, Instances train)` Perform attribute selection with a particular evaluator and a set of options specifying search method and options for the search method and evaluator.
    `void` | `SelectAttributes(Instances data)` Perform attribute selection on the supplied training instances.
    `void` | `selectAttributesCVSplit(Instances split)` Select attributes for a split of the data.
    `int[]` | `selectedAttributes()` get the final selected set of attributes.
    `void` | `setEvaluator(ASEvaluation evaluator)` set the attribute/subset evaluator
    `void` | `setFolds(int folds)` set the number of folds for cross validation
    `void` | `setRanking(boolean r)` produce a ranking (if possible with the set search and evaluator)
    `void` | `setSearch(ASSearch search)` set the search method
    `void` | `setSeed(int s)` set the seed for use in cross validation
    `void` | `setXval(boolean x)` do a cross validation
    `java.lang.String` | `toResultsString()` get a description of the attribute selection

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

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

- - ### Constructor Detail

    - #### AttributeSelection

          public AttributeSelection()

      constructor. Sets defaults for each member varaible. Default attribute evaluator is CfsSubsetEval; default search method is BestFirst.

  - ### Method Detail

    - #### numberAttributesSelected

          public int numberAttributesSelected()
                                       throws java.lang.Exception

      Return the number of attributes selected from the most recent run of attribute selection
      Returns:
        the number of attributes selected
      Throws:
        `java.lang.Exception`

    - #### selectedAttributes

          public int[] selectedAttributes()
                                   throws java.lang.Exception

      get the final selected set of attributes.
      Returns:
        an array of attribute indexes
      Throws:
        `java.lang.Exception` - if attribute selection has not been performed yet

    - #### rankedAttributes

          public double[][] rankedAttributes()
                                      throws java.lang.Exception

      get the final ranking of the attributes.
      Returns:
        a two dimensional array of ranked attribute indexes and their associated merit scores as doubles.
      Throws:
        `java.lang.Exception` - if a ranking has not been produced

    - #### setEvaluator

          public void setEvaluator(ASEvaluation evaluator)

      set the attribute/subset evaluator
      Parameters:
        `evaluator` - the evaluator to use

    - #### setSearch

          public void setSearch(ASSearch search)

      set the search method
      Parameters:
        `search` - the search method to use

    - #### setFolds

          public void setFolds(int folds)

      set the number of folds for cross validation
      Parameters:
        `folds` - the number of folds

    - #### setRanking

          public void setRanking(boolean r)

      produce a ranking (if possible with the set search and evaluator)
      Parameters:
        `r` - true if a ranking is to be produced

    - #### setXval

          public void setXval(boolean x)

      do a cross validation
      Parameters:
        `x` - true if a cross validation is to be performed

    - #### setSeed

          public void setSeed(int s)

      set the seed for use in cross validation
      Parameters:
        `s` - the seed

    - #### toResultsString

          public java.lang.String toResultsString()

      get a description of the attribute selection
      Returns:
        a String describing the results of attribute selection

    - #### reduceDimensionality

          public Instances reduceDimensionality(Instances in)
                                         throws java.lang.Exception

      reduce the dimensionality of a set of instances to include only those attributes chosen by the last run of attribute selection.
      Parameters:
        `in` - the instances to be reduced
      Returns:
        a dimensionality reduced set of instances
      Throws:
        `java.lang.Exception` - if the instances can't be reduced

    - #### reduceDimensionality

          public Instance reduceDimensionality(Instance in)
                                        throws java.lang.Exception

      reduce the dimensionality of a single instance to include only those attributes chosen by the last run of attribute selection.
      Parameters:
        `in` - the instance to be reduced
      Returns:
        a dimensionality reduced instance
      Throws:
        `java.lang.Exception` - if the instance can't be reduced

    - #### SelectAttributes

          public static java.lang.String SelectAttributes(ASEvaluation ASEvaluator,
                                          java.lang.String[] options)
                                                   throws java.lang.Exception

      Perform attribute selection with a particular evaluator and a set of options specifying search method and input file etc.
      Parameters:
        `ASEvaluator` - an evaluator object
        `options` - an array of options, not only for the evaluator but also the search method (if any) and an input data file
      Returns:
        the results of attribute selection as a String
      Throws:
        `java.lang.Exception` - if no training file is set

    - #### CVResultsString

          public java.lang.String CVResultsString()
                                           throws java.lang.Exception

      returns a string summarizing the results of repeated attribute selection runs on splits of a dataset.
      Returns:
        a summary of attribute selection results
      Throws:
        `java.lang.Exception` - if no attribute selection has been performed.

    - #### selectAttributesCVSplit

          public void selectAttributesCVSplit(Instances split)
                                       throws java.lang.Exception

      Select attributes for a split of the data. Calling this function updates the statistics on attribute selection. CVResultsString() returns a string summarizing the results of repeated calls to this function. Assumes that splits are from the same dataset--- ie. have the same number and types of attributes as previous splits.
      Parameters:
        `split` - the instances to select attributes from
      Throws:
        `java.lang.Exception` - if an error occurs

    - #### CrossValidateAttributes

          public java.lang.String CrossValidateAttributes()
                                                   throws java.lang.Exception

      Perform a cross validation for attribute selection. With subset evaluators the number of times each attribute is selected over the cross validation is reported. For attribute evaluators, the average merit and average ranking + std deviation is reported for each attribute.
      Returns:
        the results of cross validation as a String
      Throws:
        `java.lang.Exception` - if an error occurs during cross validation

    - #### SelectAttributes

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

      Perform attribute selection on the supplied training instances.
      Parameters:
        `data` - the instances to select attributes from
      Throws:
        `java.lang.Exception` - if there is a problem during selection

    - #### SelectAttributes

          public static java.lang.String SelectAttributes(ASEvaluation ASEvaluator,
                                          java.lang.String[] options,
                                          Instances train)
                                                   throws java.lang.Exception

      Perform attribute selection with a particular evaluator and a set of options specifying search method and options for the search method and evaluator.
      Parameters:
        `ASEvaluator` - an evaluator object
        `options` - an array of options, not only for the evaluator but also the search method (if any) and an input data file
        `train` - the input instances
      Returns:
        the results of attribute selection as a String
      Throws:
        `java.lang.Exception` - if incorrect options are supplied

    - #### main

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

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

    - #### getRevision

          public java.lang.String getRevision()

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