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Class weka.filters.FirstOrderFilter 

java.lang.Object
   |
   +----weka.filters.Filter
           |
           +----weka.filters.FirstOrderFilter
public class FirstOrderFilter
extends Filter
implements 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, 0.1, -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: 1.4 $
Author:
Len Trigg (trigg@cs.waikato.ac.nz)

Constructor Index

o FirstOrderFilter()

Method Index

o getAttributeIndices()
Get the current range selection
o getOptions()
Gets the current settings of the filter.
o input(Instance)
Input an instance for filtering.
o inputFormat(Instances)
Sets the format of the input instances.
o listOptions()
Returns an enumeration describing the available options
o main(String[])
Main method for testing this class.
o setAttributeIndices(String)
Set which attributes are to be deleted (or kept if invert is true)
o setAttributeIndicesArray(int[])
Set which attributes are to be deleted (or kept if invert is true)
o setOptions(String[])
Parses a given list of options controlling the behaviour of this object.

Constructors

o FirstOrderFilter 
 public FirstOrderFilter()

Methods

o listOptions 
 public Enumeration listOptions()
Returns an enumeration describing the available options

Returns:
an enumeration of all the available options
o setOptions 
 public void setOptions(String options[]) throws 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)

Parameters:
options - the list of options as an array of strings
Throws: Exception
if an option is not supported
o getOptions 
 public String[] getOptions()
Gets the current settings of the filter.

Returns:
an array of strings suitable for passing to setOptions
o inputFormat 
 public boolean inputFormat(Instances instanceInfo) throws Exception
Sets the format of the input instances.

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: Exception
if any of the selected attributes are not numeric
Overrides:
inputFormat in class Filter
o input 
 public boolean input(Instance instance) throws Exception
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.

Parameters:
instance - the input instance
Returns:
true if the filtered instance may now be collected with output().
Throws: Exception
if the input instance was not of the correct format or if there was a problem with the filtering.
Overrides:
input in class Filter
o getAttributeIndices 
 public String getAttributeIndices()
Get the current range selection

Returns:
a string containing a comma separated list of ranges
o setAttributeIndices 
 public void setAttributeIndices(String rangeList) throws 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: Exception
if an invalid range list is supplied
o setAttributeIndicesArray 
 public void setAttributeIndicesArray(int attributes[]) throws 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: Exception
if an invalid set of ranges is supplied
o main 
 public static void main(String argv[])
Main method for testing this class.

Parameters:
argv - should contain arguments to the filter: use -h for help 
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