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Class weka.filters.AttributeExpressionFilter

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

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.

Version:
$Revision: 1.10 $
Author:
Mark Hall (mhall@cs.waikato.ac.nz)

Constructor Index

 o AttributeExpressionFilter()
 

Method Index

 o debugTipText()
Returns the tip text for this property
 o expressionTipText()
Returns the tip text for this property
 o getDebug()
Gets whether debug is set
 o getExpression()
Get the expression
 o getName()
Returns the name of the new attribute
 o getOptions()
Gets the current settings of the filter.
 o globalInfo()
Returns a string describing this filter
 o input(Instance)
Input an instance for filtering.
 o listOptions()
Returns an enumeration describing the available options
 o main(String[])
Main method for testing this class.
 o nameTipText()
Returns the tip text for this property
 o setDebug(boolean)
Set debug mode.
 o setExpression(String)
Set the expression to apply
 o setInputFormat(Instances)
Sets the format of the input instances.
 o setName(String)
Set the name for the new attribute.
 o setOptions(String[])
Parses a list of options for this object.

Constructor Detail

 o AttributeExpressionFilter
public AttributeExpressionFilter()

Method Detail

 o 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
 o listOptions
public java.util.Enumeration listOptions()
          Returns an enumeration describing the available options
Returns:
an enumeration of all the available options
 o 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.

Parameters:
options - the list of options as an array of strings
Throws:
java.lang.Exception - if an option is not supported
 o getOptions
public java.lang.String[] getOptions()
          Gets the current settings of the filter.
Returns:
an array of strings suitable for passing to setOptions
 o 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
 o 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
 o getName
public java.lang.String getName()
          Returns the name of the new attribute
Returns:
the name of the new attribute
 o 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
 o 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
 o getDebug
public boolean getDebug()
          Gets whether debug is set
Returns:
true if debug is set
 o 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
 o setExpression
public void setExpression(java.lang.String expr)
          Set the expression to apply
Parameters:
expr - a mathematical expression to apply
 o getExpression
public java.lang.String getExpression()
          Get the expression
Returns:
the expression
 o setInputFormat
public boolean setInputFormat(Instances instanceInfo) throws java.lang.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:
java.lang.Exception - if the format couldn't be set successfully
Overrides:
setInputFormat in class Filter
 o 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.
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.
Overrides:
input in class Filter
 o 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

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