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Class weka.filters.InstanceFilter

java.lang.Object
   |
   +----weka.filters.Filter
           |
           +----weka.filters.InstanceFilter

public class InstanceFilter
extends Filter
implements OptionHandler
Filters instances according to the value of an attribute.

Valid filter-specific options are:

-C num
Choose attribute to be used for selection (default last).

-S num
Numeric value to be used for selection on numeric attribute. Instances with values smaller than given value will be selected. (default 0)

-L index1,index2-index4,...
Range of label indices to be used for selection on nominal attribute. First and last are valid indexes. (default all values)

-M
Missing values count as a match. This setting is independent of the -V option. (default missing values don't match)

-V
Invert matching sense.

-H
When selecting on nominal attributes, removes header references to excluded values.

Author:
Eibe Frank (eibe@cs.waikato.ac.nz)

Constructor Index

 o InstanceFilter()
Default constructor

Method Index

 o getAttributeIndex()
Get the attribute to be used for selection (-1 for last)
 o getInvertSelection()
Get whether the supplied columns are to be removed or kept
 o getMatchMissingValues()
Gets whether missing values are counted as a match.
 o getModifyHeader()
Gets whether the header will be modified when selecting on nominal attributes.
 o getNominalIndices()
Get the set of nominal value indices that will be used for selection
 o getOptions()
Gets the current settings of the filter.
 o getSplitPoint()
Get the split point used for numeric selection
 o input(Instance)
Input an instance for filtering.
 o isNominal()
Returns true if selection attribute is nominal.
 o isNumeric()
Returns true if selection attribute is numeric.
 o listOptions()
Returns an enumeration describing the available options
 o main(String[])
Main method for testing this class.
 o setAttributeIndex(int)
Sets attribute to be used for selection
 o setInputFormat(Instances)
Sets the format of the input instances.
 o setInvertSelection(boolean)
Set whether selected values should be removed or kept.
 o setMatchMissingValues(boolean)
Sets whether missing values are counted as a match.
 o setModifyHeader(boolean)
Sets whether the header will be modified when selecting on nominal attributes.
 o setNominalIndices(String)
Set which nominal labels are to be included in the selection.
 o setNominalIndicesArr(int[])
Set which values of a nominal attribute are to be used for selection.
 o setOptions(String[])
Parses a given list of options.
 o setSplitPoint(double)
Split point to be used for selection on numeric attribute.

Constructors

 o InstanceFilter
 public InstanceFilter()
Default constructor

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. Valid options are:

-C num
Choose attribute to be used for selection (default last).

-S num
Numeric value to be used for selection on numeric attribute. Instances with values smaller than given value will be selected. (default 0)

-L index1,index2-index4,...
Range of label indices to be used for selection on nominal attribute. First and last are valid indexes. (default all values)

-M
Missing values count as a match. This setting is independent of the -V option. (default missing values don't match)

-V
Invert matching sense.

-H
When selecting on nominal attributes, removes header references to excluded values.

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 setInputFormat
 public boolean setInputFormat(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).
Throws: UnsupportedAttributeTypeException
if the specified attribute is neither numeric or nominal.
Overrides:
setInputFormat in class Filter
 o 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.

Parameters:
instance - the input instance
Returns:
true if the filtered instance may now be collected with output().
Throws: IllegalStateException
if no input format has been set.
Overrides:
input in class Filter
 o isNominal
 public boolean isNominal()
Returns true if selection attribute is nominal.

Returns:
true if selection attribute is nominal
 o isNumeric
 public boolean isNumeric()
Returns true if selection attribute is numeric.

Returns:
true if selection attribute is numeric
 o getModifyHeader
 public boolean getModifyHeader()
Gets whether the header will be modified when selecting on nominal attributes.

Returns:
true if so.
 o setModifyHeader
 public void setModifyHeader(boolean newModifyHeader)
Sets whether the header will be modified when selecting on nominal attributes.

Parameters:
newModifyHeader - true if so.
 o getAttributeIndex
 public int getAttributeIndex()
Get the attribute to be used for selection (-1 for last)

Returns:
the attribute index
 o setAttributeIndex
 public void setAttributeIndex(int attribute)
Sets attribute to be used for selection

Parameters:
attribute - the attribute's index (-1 for last);
 o getSplitPoint
 public double getSplitPoint()
Get the split point used for numeric selection

Returns:
the numeric split point
 o setSplitPoint
 public void setSplitPoint(double value)
Split point to be used for selection on numeric attribute.

Parameters:
value - the split point
 o getMatchMissingValues
 public boolean getMatchMissingValues()
Gets whether missing values are counted as a match.

Returns:
true if missing values are counted as a match.
 o setMatchMissingValues
 public void setMatchMissingValues(boolean newMatchMissingValues)
Sets whether missing values are counted as a match.

Parameters:
newMatchMissingValues - true if missing values are counted as a match.
 o getInvertSelection
 public boolean getInvertSelection()
Get whether the supplied columns are to be removed or kept

Returns:
true if the supplied columns will be kept
 o setInvertSelection
 public void setInvertSelection(boolean invert)
Set whether selected values should be removed or kept. If true the selected values are kept and unselected values are deleted.

Parameters:
invert - the new invert setting
 o getNominalIndices
 public String getNominalIndices()
Get the set of nominal value indices that will be used for selection

Returns:
rangeList a string representing the list of nominal indices.
 o setNominalIndices
 public void setNominalIndices(String rangeList)
Set which nominal labels are to be included in the selection.

Parameters:
rangeList - a string representing the list of nominal indices. eg: first-3,5,6-last
Throws: InvalidArgumentException
if an invalid range list is supplied
 o setNominalIndicesArr
 public void setNominalIndicesArr(int values[])
Set which values of a nominal attribute are to be used for selection.

Parameters:
values - an array containing indexes of values to be used for selection
Throws: InvalidArgumentException
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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