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## weka.filters.unsupervised.attribute
Class MathExpression

    java.lang.Object
      weka.filters.Filter
          weka.filters.unsupervised.attribute.PotentialClassIgnorer
              weka.filters.unsupervised.attribute.MathExpression

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

    public class MathExpression

extends PotentialClassIgnorer
implements UnsupervisedFilter

Modify numeric attributes according to a given expression

Valid options are:

     -unset-class-temporarily
      Unsets the class index temporarily before the filter is
      applied to the data.
      (default: no)

     -E <expression>
      Specify the expression to apply. Eg. pow(A,6)/(MEAN+MAX)
      Supported operators are +, -, *, /, pow, log,
      abs, cos, exp, sqrt, tan, sin, ceil, floor, rint, (, ),
      MEAN, MAX, MIN, SD, COUNT, SUM, SUMSQUARED, ifelse

     -R <index1,index2-index4,...>
      Specify list of columns to ignore. First and last are valid
      indexes. (default none)

     -V
      Invert matching sense (i.e. only modify specified columns)

Version:
  $Revision: 5543 $
Author:
  Eibe Frank (eibe@cs.waikato.ac.nz), Prados Julien (julien.prados@cui.unige.ch)
See Also:
  `MathematicalExpression`, Serialized Form

Field Summary
`static java.lang.String` | `m_defaultExpression` The default modification expression

Constructor Summary
`MathExpression()` Constructor

Method Summary
`boolean` | `batchFinished()` Signify that this batch of input to the filter is finished.
`java.lang.String` | `expressionTipText()` Returns the tip text for this property
`Capabilities` | `getCapabilities()` Returns the Capabilities of this filter.
`java.lang.String` | `getExpression()` Get the expression
`java.lang.String` | `getIgnoreRange()` Get the current range selection.
`boolean` | `getInvertSelection()` Get whether the supplied columns are to be select or unselect
`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
`java.lang.String` | `ignoreRangeTipText()` Returns the tip text for this property
`boolean` | `input(Instance instance)` Input an instance for filtering.
`java.lang.String` | `invertSelectionTipText()` Returns the tip text for this property
`java.util.Enumeration` | `listOptions()` Returns an enumeration describing the available options.
`static void` | `main(java.lang.String[] argv)` Main method for testing this class.
`void` | `setExpression(java.lang.String expr)` Set the expression to apply
`void` | `setIgnoreRange(java.lang.String rangeList)` Set which attributes are to be ignored
`boolean` | `setInputFormat(Instances instanceInfo)` Sets the format of the input instances.
`void` | `setInvertSelection(boolean invert)` Set whether selected columns should be select or unselect.
`void` | `setOptions(java.lang.String[] options)` Parses a given list of options.

Methods inherited from class weka.filters.unsupervised.attribute.PotentialClassIgnorer
`getIgnoreClass, getOutputFormat, ignoreClassTipText, setIgnoreClass`

Methods inherited from class weka.filters.Filter
`batchFilterFile, filterFile, getCapabilities, isFirstBatchDone, isNewBatch, isOutputFormatDefined, makeCopies, makeCopy, numPendingOutput, output, outputPeek, toString, useFilter, wekaStaticWrapper`

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

Field Detail

### m_defaultExpression

    public static final java.lang.String m_defaultExpression

  The default modification expression

  See Also:
    Constant Field Values

Constructor Detail

### MathExpression

    public MathExpression()

  Constructor

Method Detail

### 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

### 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 `PotentialClassIgnorer`
  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 input format can't be set successfully

### input

    public boolean input(Instance instance)
                  throws java.lang.Exception

  Input an instance for filtering. Filter requires all training instances be read before producing output.

  Overrides:
    `input` in class `Filter`
  Parameters:
    `instance` - the input instance
  Returns:
    true if the filtered instance may now be collected with output().
  Throws:
    `java.lang.IllegalStateException` - if no input format has been set.
    `java.lang.NullPointerException` - if the input format has not been defined.
    `java.lang.Exception` - if the input instance was not of the correct format or if there was a problem with the filtering.

### batchFinished

    public boolean batchFinished()
                          throws java.lang.Exception

  Signify that this batch of input to the filter is finished. If the filter requires all instances prior to filtering, output() may now be called to retrieve the filtered instances.

  Overrides:
    `batchFinished` in class `Filter`
  Returns:
    true if there are instances pending output
  Throws:
    `java.lang.IllegalStateException` - if no input structure has been defined
    `java.lang.NullPointerException` - if no input structure has been defined,
    `java.lang.Exception` - if there was a problem finishing the batch.

### setOptions

    public void setOptions(java.lang.String[] options)
                    throws java.lang.Exception

  Parses a given list of options.

  Valid options are:

       -unset-class-temporarily
        Unsets the class index temporarily before the filter is
        applied to the data.
        (default: no)

       -E <expression>
        Specify the expression to apply. Eg. pow(A,6)/(MEAN+MAX)
        Supported operators are +, -, *, /, pow, log,
        abs, cos, exp, sqrt, tan, sin, ceil, floor, rint, (, ),
        MEAN, MAX, MIN, SD, COUNT, SUM, SUMSQUARED, ifelse

       -R <index1,index2-index4,...>
        Specify list of columns to ignore. First and last are valid
        indexes. (default none)

       -V
        Invert matching sense (i.e. only modify specified columns)

  Specified by:
    `setOptions` in interface `OptionHandler`
  Overrides:
    `setOptions` in class `PotentialClassIgnorer`
  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 `PotentialClassIgnorer`
  Returns:
    an array of strings suitable for passing to setOptions

### listOptions

    public java.util.Enumeration listOptions()

  Returns an enumeration describing the available options.

  Specified by:
    `listOptions` in interface `OptionHandler`
  Overrides:
    `listOptions` in class `PotentialClassIgnorer`
  Returns:
    an enumeration of all the available options.

### expressionTipText

    public java.lang.String expressionTipText()

  Returns the tip text for this property

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

### setExpression

    public void setExpression(java.lang.String expr)

  Set the expression to apply

  Parameters:
    `expr` - a mathematical expression to apply

### getExpression

    public java.lang.String getExpression()

  Get the expression

  Returns:
    the expression

### invertSelectionTipText

    public java.lang.String invertSelectionTipText()

  Returns the tip text for this property

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

### getInvertSelection

    public boolean getInvertSelection()

  Get whether the supplied columns are to be select or unselect

  Returns:
    true if the supplied columns will be kept

### setInvertSelection

    public void setInvertSelection(boolean invert)

  Set whether selected columns should be select or unselect. If true the selected columns are modified. If false the selected columns are not modified.

  Parameters:
    `invert` - the new invert setting

### ignoreRangeTipText

    public java.lang.String ignoreRangeTipText()

  Returns the tip text for this property

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

### getIgnoreRange

    public java.lang.String getIgnoreRange()

  Get the current range selection.

  Returns:
    a string containing a comma separated list of ranges

### setIgnoreRange

    public void setIgnoreRange(java.lang.String rangeList)

  Set which attributes are to be ignored

  Parameters:
    `rangeList` - a string representing the list of attributes. Since the string will typically come from a user, attributes are indexed from 1.
    eg: first-3,5,6-last

### 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

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