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Class weka.attributeSelection.PrincipalComponents

java.lang.Object
   |
   +----weka.attributeSelection.ASEvaluation
           |
           +----weka.attributeSelection.AttributeEvaluator
                   |
                   +----weka.attributeSelection.PrincipalComponents

public class PrincipalComponents
extends AttributeEvaluator
implements AttributeTransformer, OptionHandler
Class for performing principal components analysis/transformation.

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

Constructor Index

 o PrincipalComponents()

Method Index

 o buildEvaluator(Instances)
Initializes principal components and performs the analysis
 o convertInstance(Instance)
Transform an instance in original (unormalized) format.
 o evaluateAttribute(int)
Evaluates the merit of a transformed attribute.
 o getNormalize()
Gets whether or not input data is to be normalized
 o getOptions()
Gets the current settings of PrincipalComponents
 o getTransformBackToOriginal()
Gets whether the data is to be transformed back to the original space.
 o getVarianceCovered()
Gets the proportion of total variance to account for when retaining principal components
 o globalInfo()
Returns a string describing this attribute transformer
 o listOptions()
Returns an enumeration describing the available options

-N Don't normalize the input data.

 o main(String[])
Main method for testing this class
 o normalizeTipText()
Returns the tip text for this property
 o setNormalize(boolean)
Set whether input data will be normalized.
 o setOptions(String[])
Parses a given list of options.
 o setTransformBackToOriginal(boolean)
Sets whether the data should be transformed back to the original space
 o setVarianceCovered(double)
Sets the amount of variance to account for when retaining principal components
 o toString()
Returns a description of this attribute transformer
 o transformBackToOriginalTipText()
Returns the tip text for this property
 o transformedData()
Gets the transformed training data.
 o transformedHeader()
Returns just the header for the transformed data (ie.
 o varianceCoveredTipText()
Returns the tip text for this property

Constructors

 o PrincipalComponents
 public PrincipalComponents()

Methods

 o globalInfo
 public String globalInfo()
Returns a string describing this attribute transformer

Returns:
a description of the evaluator suitable for displaying in the explorer/experimenter gui
 o listOptions
 public Enumeration listOptions()
Returns an enumeration describing the available options

-N Don't normalize the input data.

Returns:
an enumeration of all the available options
 o setOptions
 public void setOptions(String options[]) throws Exception
Parses a given list of options. Valid options are:

-N Don't normalize the input data.

Parameters:
options - the list of options as an array of strings
Throws: Exception
if an option is not supported
 o normalizeTipText
 public String normalizeTipText()
Returns the tip text for this property

Returns:
tip text for this property suitable for displaying in the explorer/experimenter gui
 o setNormalize
 public void setNormalize(boolean n)
Set whether input data will be normalized.

Parameters:
n - true if input data is to be normalized
 o getNormalize
 public boolean getNormalize()
Gets whether or not input data is to be normalized

Returns:
true if input data is to be normalized
 o varianceCoveredTipText
 public String varianceCoveredTipText()
Returns the tip text for this property

Returns:
tip text for this property suitable for displaying in the explorer/experimenter gui
 o setVarianceCovered
 public void setVarianceCovered(double vc)
Sets the amount of variance to account for when retaining principal components

Parameters:
vc - the proportion of total variance to account for
 o getVarianceCovered
 public double getVarianceCovered()
Gets the proportion of total variance to account for when retaining principal components

Returns:
the proportion of variance to account for
 o transformBackToOriginalTipText
 public String transformBackToOriginalTipText()
Returns the tip text for this property

Returns:
tip text for this property suitable for displaying in the explorer/experimenter gui
 o setTransformBackToOriginal
 public void setTransformBackToOriginal(boolean b)
Sets whether the data should be transformed back to the original space

Parameters:
b - true if the data should be transformed back to the original space
 o getTransformBackToOriginal
 public boolean getTransformBackToOriginal()
Gets whether the data is to be transformed back to the original space.

Returns:
true if the data is to be transformed back to the original space
 o getOptions
 public String[] getOptions()
Gets the current settings of PrincipalComponents

Returns:
an array of strings suitable for passing to setOptions()
 o buildEvaluator
 public void buildEvaluator(Instances data) throws Exception
Initializes principal components and performs the analysis

Parameters:
data - the instances to analyse/transform
Throws: Exception
if analysis fails
Overrides:
buildEvaluator in class ASEvaluation
 o transformedHeader
 public Instances transformedHeader() throws Exception
Returns just the header for the transformed data (ie. an empty set of instances. This is so that AttributeSelection can determine the structure of the transformed data without actually having to get all the transformed data through getTransformedData().

Returns:
the header of the transformed data.
Throws: Exception
if the header of the transformed data can't be determined.
 o transformedData
 public Instances transformedData() throws Exception
Gets the transformed training data.

Returns:
the transformed training data
Throws: Exception
if transformed data can't be returned
 o evaluateAttribute
 public double evaluateAttribute(int att) throws Exception
Evaluates the merit of a transformed attribute. This is defined to be 1 minus the cumulative variance explained. Merit can't be meaningfully evaluated if the data is to be transformed back to the original space.

Parameters:
att - the attribute to be evaluated
Returns:
the merit of a transformed attribute
Throws: Exception
if attribute can't be evaluated
Overrides:
evaluateAttribute in class AttributeEvaluator
 o toString
 public String toString()
Returns a description of this attribute transformer

Returns:
a String describing this attribute transformer
Overrides:
toString in class Object
 o convertInstance
 public Instance convertInstance(Instance instance) throws Exception
Transform an instance in original (unormalized) format. Convert back to the original space if requested.

Parameters:
instance - an instance in the original (unormalized) format
Returns:
a transformed instance
Throws: Exception
if instance cant be transformed
 o main
 public static void main(String argv[])
Main method for testing this class

Parameters:
argv - should contain the command line arguments to the evaluator/transformer (see AttributeSelection)

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