edu.ucla.sspace.nonlinear

Class LocalityPreservingSemanticAnalysis

java.lang.Object

edu.ucla.sspace.common.GenericTermDocumentVectorSpace

edu.ucla.sspace.nonlinear.LocalityPreservingSemanticAnalysis

All Implemented Interfaces:

SemanticSpace

public class LocalityPreservingSemanticAnalysis
extends GenericTermDocumentVectorSpace

An implementation of Locality Preserving Semantic Analysis (LPSA). LPSA is a non-linear reduction of the Vector Space Model (VSM) through use of Locality Preserving Projections (LPP). In this sense, LPSA is related to LSA, but uses a different reduction of the VSM for the final word representations. This implementation is based on the following paper.

• forthcoming

This class offers configurable preprocessing and dimensionality reduction. through two parameters.

Property: "edu.ucla.sspace.lpsa.LocalityPreservingSemanticAnalysis.transform"
Default: none.

This variable sets the preprocessing algorithm to use on the term-document matrix prior to computing the SVD. The property value should be the fully qualified named of a class that implements Transform. The class should be public, not abstract, and should provide a public no-arg constructor.

Property: "edu.ucla.sspace.lpsa.LocalityPreservingSemanticAnalysis.dimensions"
Default: 300

The number of dimensions to use for the semantic space. This value is used as input to the SVD.

This class is thread-safe for concurrent calls of processDocument. Once processSpace has been called, no further calls to processDocument should be made. This implementation does not support access to the semantic vectors until after processSpace has been called.

Author:

David Jurgens

See Also:

Transform, LocalityPreservingProjection, GenericTermDocumentVectorSpace, LSA

Field Summary

Fields

Modifier and Type	Field and Description
static String	LPSA_DIMENSIONS_PROPERTY The property to set the number of dimension to which the space should be reduced using the SVD
static String	MATRIX_TRANSFORM_PROPERTY The property to define the Transform class to be used when processing the space after all the documents have been seen.

Fields inherited from class edu.ucla.sspace.common.GenericTermDocumentVectorSpace

documentCounter, LOG, wordSpace

Constructor Summary

Constructors

Constructor and Description
LocalityPreservingSemanticAnalysis(AffinityMatrixCreator creator) Constructs the LocalityPreservingSemanticAnalysis using the system properties for configuration.

Method Summary

Methods

Modifier and Type	Method and Description
String	getSpaceName() Returns a unique string describing the name and configuration of this algorithm.
void	processSpace(Properties properties) Once all the documents have been processed, performs any post-processing steps on the data.

Methods inherited from class edu.ucla.sspace.common.GenericTermDocumentVectorSpace

getVector, getVectorLength, getWords, handleDocumentHeader, processDocument, processSpace

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MATRIX_TRANSFORM_PROPERTY

public static final String MATRIX_TRANSFORM_PROPERTY

The property to define the Transform class to be used when processing the space after all the documents have been seen.

See Also:

Constant Field Values

LPSA_DIMENSIONS_PROPERTY

public static final String LPSA_DIMENSIONS_PROPERTY

The property to set the number of dimension to which the space should be reduced using the SVD

See Also:

Constant Field Values

Constructor Detail

LocalityPreservingSemanticAnalysis

public LocalityPreservingSemanticAnalysis(AffinityMatrixCreator creator)
                                   throws IOException

Constructs the LocalityPreservingSemanticAnalysis using the system properties for configuration.

Throws:

IOException - if this instance encounters any errors when creatng the backing array files required for processing

Method Detail

getSpaceName

public String getSpaceName()

Returns a unique string describing the name and configuration of this algorithm. Any configurable parameters that would affect the resulting semantic space should be expressed as a part of this name.

processSpace

public void processSpace(Properties properties)

Once all the documents have been processed, performs any post-processing steps on the data. An algorithm should treat this as a no-op if no post-processing is required. Callers may specify the values for any exposed parameters using the properties argument.

By general contract, once this method has been called, processDocument will not be called again.

Parameters:

properties - a set of properties and values that may be used to configure any exposed parameters of the algorithm. See this class's javadoc for the full list of supported properties.