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## weka.filters.unsupervised.attribute
Class FirstOrder

    java.lang.Object
      weka.filters.Filter
          weka.filters.unsupervised.attribute.FirstOrder

All Implemented Interfaces:
  java.io.Serializable, OptionHandler, StreamableFilter, UnsupervisedFilter

    public class FirstOrder

extends Filter
implements UnsupervisedFilter, StreamableFilter, OptionHandler

This instance filter takes a range of N numeric attributes and replaces them with N-1 numeric attributes, the values of which are the difference between consecutive attribute values from the original instance. eg:

Original attribute values
`0.1, 0.2, 0.3, 0.1, 0.3`

New attribute values
`0.1, 0.1, -0.2, 0.2`

The range of attributes used is taken in numeric order. That is, a range spec of 7-11,3-5 will use the attribute ordering 3,4,5,7,8,9,10,11 for the differences, not 7,8,9,10,11,3,4,5.

Valid filter-specific options are:

-R index1,index2-index4,...
Specify list of columns to take the differences between. First and last are valid indexes. (default none)

Version:
  $Revision: 1.3.2.1 $
Author:
  Len Trigg (trigg@cs.waikato.ac.nz)
See Also:
  Serialized Form

Constructor Summary
`FirstOrder()`

Method Summary
`java.lang.String` | `attributeIndicesTipText()` Returns the tip text for this property
`java.lang.String` | `getAttributeIndices()` Get the current range selection
`java.lang.String[]` | `getOptions()` Gets the current settings of the filter.
`java.lang.String` | `globalInfo()` Returns a string describing this filter
`boolean` | `input(Instance instance)` Input an instance for filtering.
`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` | `setAttributeIndices(java.lang.String rangeList)` Set which attributes are to be deleted (or kept if invert is true)
`void` | `setAttributeIndicesArray(int[] attributes)` Set which attributes are to be deleted (or kept if invert is true)
`boolean` | `setInputFormat(Instances instanceInfo)` Sets the format of the input instances.
`void` | `setOptions(java.lang.String[] options)` Parses a given list of options controlling the behaviour of this object.

Methods inherited from class weka.filters.Filter
`batchFilterFile, batchFinished, filterFile, getOutputFormat, inputFormat, isOutputFormatDefined, numPendingOutput, output, outputFormat, outputPeek, useFilter`

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

Constructor Detail

### FirstOrder

    public FirstOrder()

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

### 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 controlling the behaviour of this object. Valid options are:

  -R index1,index2-index4,...
  Specify list of columns to take the differences between. First and last are valid indexes. (default none)

  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

### getOptions

    public java.lang.String[] getOptions()

  Gets the current settings of the filter.

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

### 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:
    `UnsupportedAttributeTypeException` - if any of the selected attributes are not numeric
    `java.lang.Exception` - if only one attribute has been selected.

### input

    public boolean input(Instance instance)

  Input an instance for filtering. Ordinarily the instance is processed and made available for output immediately. Some filters require all 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 defined.

### attributeIndicesTipText

    public java.lang.String attributeIndicesTipText()

  Returns the tip text for this property

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

### getAttributeIndices

    public java.lang.String getAttributeIndices()

  Get the current range selection

  Returns:
    a string containing a comma separated list of ranges

### setAttributeIndices

    public void setAttributeIndices(java.lang.String rangeList)
                             throws java.lang.Exception

  Set which attributes are to be deleted (or kept if invert is true)

  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
  Throws:
    `java.lang.Exception` - if an invalid range list is supplied

### setAttributeIndicesArray

    public void setAttributeIndicesArray(int[] attributes)
                                  throws java.lang.Exception

  Set which attributes are to be deleted (or kept if invert is true)

  Parameters:
    `attributes` - an array containing indexes of attributes to select. Since the array will typically come from a program, attributes are indexed from 0.
  Throws:
    `java.lang.Exception` - if an invalid set of ranges is supplied

### 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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