weka.filters.unsupervised.attribute

Class AddExpression

java.lang.Object

weka.filters.Filter

weka.filters.unsupervised.attribute.AddExpression

All Implemented Interfaces:

Serializable, CapabilitiesHandler, OptionHandler, RevisionHandler, StreamableFilter, UnsupervisedFilter

public class AddExpression
extends Filter
implements UnsupervisedFilter, StreamableFilter, OptionHandler

An instance filter that creates a new attribute by applying a mathematical expression to existing attributes. The expression can contain attribute references and numeric constants. 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).
Example expression : a1^2*a5/log(a7*4.0).

Valid options are:

 -E <expression>
  Specify the expression to apply. Eg a1^2*a5/log(a7*4.0).
  Supported opperators: ,+, -, *, /, ^, log, abs, cos, 
  exp, sqrt, floor, ceil, rint, tan, sin, (, )
  (default: a1^2)
 

 -N <name>
  Specify the name for the new attribute. (default is the expression provided with -E)
 

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

Version:

$Revision: 10215 $

Author:

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

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AddExpression()

Method Summary

Methods

Modifier and Type	Method and Description
String	debugTipText() Returns the tip text for this property
String	expressionTipText() Returns the tip text for this property
Capabilities	getCapabilities() Returns the Capabilities of this filter.
boolean	getDebug() Gets whether debug is set
String	getExpression() Get the expression
String	getName() Returns the name of the new attribute
String[]	getOptions() Gets the current settings of the filter.
String	getRevision() Returns the revision string.
String	globalInfo() Returns a string describing this filter
boolean	input(Instance instance) Input an instance for filtering.
Enumeration<Option>	listOptions() Returns an enumeration describing the available options.
static void	main(String[] args) Main method for testing this class.
String	nameTipText() Returns the tip text for this property
void	setDebug(boolean d) Set debug mode.
void	setExpression(String expr) Set the expression to apply
boolean	setInputFormat(Instances instanceInfo) Sets the format of the input instances.
void	setName(String name) Set the name for the new attribute.
void	setOptions(String[] options) Parses a given list of options.

Methods inherited from class weka.filters.Filter

batchFilterFile, batchFinished, filterFile, getCapabilities, getOutputFormat, isFirstBatchDone, isNewBatch, isOutputFormatDefined, makeCopies, makeCopy, mayRemoveInstanceAfterFirstBatchDone, numPendingOutput, output, outputPeek, runFilter, toString, useFilter, wekaStaticWrapper

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AddExpression

public AddExpression()

Method Detail

globalInfo

public String globalInfo()

Returns a string describing this filter

Returns:

a description of the filter suitable for displaying in the explorer/experimenter gui

listOptions

public Enumeration<Option> 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(String[] options)
                throws Exception

Parses a given list of options.

Valid options are:

 -E <expression>
  Specify the expression to apply. Eg a1^2*a5/log(a7*4.0).
  Supported opperators: ,+, -, *, /, ^, log, abs, cos, 
  exp, sqrt, floor, ceil, rint, tan, sin, (, )
  (default: a1^2)
 

 -N <name>
  Specify the name for the new attribute. (default is the expression provided with -E)
 

 -D
  Debug. Names 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:

Exception - if an option is not supported

getOptions

public 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 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(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 String getName()

Returns the name of the new attribute

Returns:

the name of the new attribute

debugTipText

public 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 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(String expr)

Set the expression to apply

Parameters:

expr - a mathematical expression to apply

getExpression

public String getExpression()

Get the expression

Returns:

the expression

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 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:

Exception - if the format couldn't be set successfully

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.

Overrides:

input in class Filter

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 defined.

Exception - if there was a problem during the filtering.

getRevision

public 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(String[] args)

Main method for testing this class.

Parameters:

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