weka.filters.unsupervised.attribute

## Class RemoveUseless

- java.lang.Object
- - weka.filters.Filter
  - - weka.filters.unsupervised.attribute.RemoveUseless

- All Implemented Interfaces:
    java.io.Serializable, CapabilitiesHandler, CapabilitiesIgnorer, OptionHandler, RevisionHandler, UnsupervisedFilter

      public class RemoveUseless
      extends Filter
      implements UnsupervisedFilter, OptionHandler

  This filter removes attributes that do not vary at all or that vary too much. All constant attributes are deleted automatically, along with any that exceed the maximum percentage of variance parameter. The maximum variance test is only applied to nominal attributes.

  Valid options are:

       -M <max variance %>
        Maximum variance percentage allowed (default 99)

  Version:
    $Revision: 10215 $
  Author:
    Richard Kirkby (rkirkby@cs.waikato.ac.nz)
  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `RemoveUseless()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `batchFinished()` Signify that this batch of input to the filter is finished.
    `Capabilities` | `getCapabilities()` Returns the Capabilities of this filter.
    `double` | `getMaximumVariancePercentageAllowed()` Gets the maximum variance attributes are allowed to have before they are deleted by the filter.
    `java.lang.String[]` | `getOptions()` Gets the current settings of the filter.
    `java.lang.String` | `getRevision()` Returns the revision string.
    `java.lang.String` | `globalInfo()` Returns a string describing this filter
    `boolean` | `input(Instance instance)` Input an instance for filtering.
    `java.util.Enumeration<Option>` | `listOptions()` Returns an enumeration describing the available options.
    `static void` | `main(java.lang.String[] argv)` Main method for testing this class.
    `java.lang.String` | `maximumVariancePercentageAllowedTipText()` Returns the tip text for this property
    `boolean` | `setInputFormat(Instances instanceInfo)` Sets the format of the input instances.
    `void` | `setMaximumVariancePercentageAllowed(double maxVariance)` Sets the maximum variance attributes are allowed to have before they are deleted by the filter.
    `void` | `setOptions(java.lang.String[] options)` Parses a given list of options.

    - ### Methods inherited from class weka.filters.Filter

      `batchFilterFile, debugTipText, doNotCheckCapabilitiesTipText, filterFile, getCapabilities, getDebug, getDoNotCheckCapabilities, getOutputFormat, isFirstBatchDone, isNewBatch, isOutputFormatDefined, makeCopies, makeCopy, mayRemoveInstanceAfterFirstBatchDone, numPendingOutput, output, outputPeek, runFilter, setDebug, setDoNotCheckCapabilities, toString, useFilter, wekaStaticWrapper`

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

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

- - ### Constructor Detail

    - #### RemoveUseless

          public RemoveUseless()

  - ### Method Detail

    - #### getCapabilities

          public Capabilities getCapabilities()

      Returns the Capabilities of this filter.
      Specified by:
        `getCapabilities` in interface `CapabilitiesHandler`
      Overrides:
        `getCapabilities` in class `Filter`
      Returns:
        the capabilities of this object
      See Also:
        `Capabilities`

    - #### setInputFormat

          public boolean setInputFormat(Instances instanceInfo)
                                 throws java.lang.Exception

      Sets the format of the input instances.
      Overrides:
        `setInputFormat` in class `Filter`
      Parameters:
        `instanceInfo` - an Instances object containing the input instance structure (any instances contained in the object are ignored - only the structure is required).
      Returns:
        true if the outputFormat may be collected immediately
      Throws:
        `java.lang.Exception` - if the inputFormat can't be set successfully

    - #### input

          public boolean input(Instance instance)

      Input an instance for filtering.
      Overrides:
        `input` in class `Filter`
      Parameters:
        `instance` - the input instance
      Returns:
        true if the filtered instance may now be collected with output().

    - #### batchFinished

          public boolean batchFinished()
                                throws java.lang.Exception

      Signify that this batch of input to the filter is finished.
      Overrides:
        `batchFinished` in class `Filter`
      Returns:
        true if there are instances pending output
      Throws:
        `java.lang.Exception` - if no input format defined

    - #### listOptions

          public java.util.Enumeration<Option> listOptions()

      Returns an enumeration describing the available options.
      Specified by:
        `listOptions` in interface `OptionHandler`
      Overrides:
        `listOptions` in class `Filter`
      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 <max variance %>
            Maximum variance percentage allowed (default 99)

      Specified by:
        `setOptions` in interface `OptionHandler`
      Overrides:
        `setOptions` in class `Filter`
      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 the filter.
      Specified by:
        `getOptions` in interface `OptionHandler`
      Overrides:
        `getOptions` in class `Filter`
      Returns:
        an array of strings suitable for passing to setOptions

    - #### globalInfo

          public java.lang.String globalInfo()

      Returns a string describing this filter
      Returns:
        a description of the filter suitable for displaying in the explorer/experimenter gui

    - #### maximumVariancePercentageAllowedTipText

          public java.lang.String maximumVariancePercentageAllowedTipText()

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

    - #### setMaximumVariancePercentageAllowed

          public void setMaximumVariancePercentageAllowed(double maxVariance)

      Sets the maximum variance attributes are allowed to have before they are deleted by the filter.
      Parameters:
        `maxVariance` - the maximum variance allowed, specified as a percentage

    - #### getMaximumVariancePercentageAllowed

          public double getMaximumVariancePercentageAllowed()

      Gets the maximum variance attributes are allowed to have before they are deleted by the filter.
      Returns:
        the maximum variance allowed, specified as a percentage

    - #### getRevision

          public java.lang.String getRevision()

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

    - #### main

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

      Main method for testing this class.
      Parameters:
        `argv` - should contain arguments to the filter: use -h for help