weka.filters
Class AttributeExpressionFilter

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

All Implemented Interfaces:

OptionHandler, java.io.Serializable

public class AttributeExpressionFilter

extends Filter

implements OptionHandler

Applys a mathematical expression involving attributes and numeric constants to a dataset. A new attribute is appended after the last attribute that contains the result of applying the expression. Supported operators are: +, -, *, /, ^, log, abs, cos, exp, sqrt, floor, ceil, rint, tan, sin, (, ). Attributes are specified by prefixing with 'a', eg. a7 is attribute number 7 (starting from 1).

Valid filter-specific options are:

-E expression
Specify the expression to apply. Eg. a1^2*a5/log(a7*4.0).

-N name
Specify a name for the new attribute. Default is to name it with the expression provided with the -E option.

-D
Debug. Names the attribute with the postfix parse of the expression.

Author:

Mark Hall (mhall@cs.waikato.ac.nz)

See Also:

Serialized Form

Fields inherited from class weka.filters.Filter

m_NewBatch

Constructor Summary

AttributeExpressionFilter()

Method Summary

java.lang.String	debugTipText() Returns the tip text for this property
java.lang.String	expressionTipText() Returns the tip text for this property
boolean	getDebug() Gets whether debug is set
java.lang.String	getExpression() Get the expression
java.lang.String	getName() Returns the name of the new attribute
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[] args) Main method for testing this class.
java.lang.String	nameTipText() Returns the tip text for this property
void	setDebug(boolean d) Set debug mode.
void	setExpression(java.lang.String expr) Set the expression to apply
boolean	setInputFormat(Instances instanceInfo) Sets the format of the input instances.
void	setName(java.lang.String name) Set the name for the new attribute.
void	setOptions(java.lang.String[] options) Parses a list of options for this object.

Methods inherited from class weka.filters.Filter

batchFilterFile, batchFinished, bufferInput, copyStringValues, copyStringValues, filterFile, flushInput, getInputFormat, getInputStringIndex, getOutputFormat, getOutputStringIndex, getStringIndices, inputFormat, isOutputFormatDefined, numPendingOutput, output, outputFormat, outputFormatPeek, outputPeek, push, resetQueue, setOutputFormat, useFilter

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AttributeExpressionFilter

public AttributeExpressionFilter()

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 list of options for this object. Valid options are:

-E expression
Specify the expression to apply. Eg. a1^2*a5/log(a7*4.0).

-N name
Specify a name for the new attribute. Default is to name it with the expression provided with the -E option.

-D
Debug. Names the attribute with the postfix parse of the expression.

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

nameTipText

public java.lang.String nameTipText()

Returns the tip text for this property

Returns:

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

setName

public void setName(java.lang.String name)

Set the name for the new attribute. The string "expression" can be used to make the name of the new attribute equal to the expression provided.

Parameters:

name - the name of the new attribute

getName

public java.lang.String getName()

Returns the name of the new attribute

Returns:

the name of the new attribute

debugTipText

public java.lang.String debugTipText()

Returns the tip text for this property

Returns:

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

setDebug

public void setDebug(boolean d)

Set debug mode. Causes the new attribute to be named with the postfix parse of the expression

Parameters:

d - true if debug mode is to be used

getDebug

public boolean getDebug()

Gets whether debug is set

Returns:

true if debug is set

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

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 format couldn't be set successfully

input

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

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.

java.lang.Exception - if there was a problem during the filtering.

main

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

Main method for testing this class.

Parameters:

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