Package weka.filters.unsupervised.attribute

Class AddExpression

java.lang.Object
weka.filters.Filter
weka.filters.unsupervised.attribute.AddExpression
All Implemented Interfaces:
Serializable, CapabilitiesHandler, CapabilitiesIgnorer, CommandlineRunnable, OptionHandler, RevisionHandler, WeightedAttributesHandler, WeightedInstancesHandler, StreamableFilter, UnsupervisedFilter
public class AddExpression extends Filter implements UnsupervisedFilter, StreamableFilter, OptionHandler, WeightedInstancesHandler, WeightedAttributesHandler
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: 0.0)
 
 -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: 14508 $
Author:
Mark Hall (mhall@cs.waikato.ac.nz)
See Also:

  • Constructor Details

    • AddExpression

      public AddExpression()

  • Method Details

    • 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
      Overrides:
      listOptions in class Filter
      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
      Overrides:
      setOptions in class Filter
      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
      Overrides:
      getOptions in class Filter
      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
      Overrides:
      debugTipText in class Filter
      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
      Overrides:
      setDebug in class Filter
      Parameters:
      d - true if debug mode is to be used

    • getDebug

      public boolean getDebug()
      Gets whether debug is set
      Overrides:
      getDebug in class Filter
      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:

    • 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