weka.filters.unsupervised.attribute
Class AddExpression

java.lang.Object
  extended by weka.filters.Filter
      extended by weka.filters.unsupervised.attribute.AddExpression
All Implemented Interfaces:
java.io.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: 1.8 $
Author:
Mark Hall (mhall@cs.waikato.ac.nz)
See Also:
Serialized Form

Constructor Summary
AddExpression()
           
 
Method Summary
 java.lang.String debugTipText()
          Returns the tip text for this property
 java.lang.String expressionTipText()
          Returns the tip text for this property
 Capabilities getCapabilities()
          Returns the Capabilities of this filter.
 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 getRevision()
          Returns the revision string.
 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 given list of options.
 
Methods inherited from class weka.filters.Filter
batchFilterFile, batchFinished, filterFile, getCapabilities, getOutputFormat, isFirstBatchDone, isNewBatch, isOutputFormatDefined, makeCopies, makeCopy, numPendingOutput, output, outputPeek, 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 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.

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:
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

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 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.

getRevision

public java.lang.String getRevision()
Returns the revision string.

Specified by:
getRevision in interface RevisionHandler
Returns:
the revision

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