weka.attributeSelection.LatentSemanticAnalysis Maven / Gradle / Ivy
/*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see -N
* Normalize input data.
*
* -R
* Rank approximation used in LSA. May be actual number of
* LSA attributes to include (if greater than 1) or a proportion
* of total singular values to account for (if between 0 and 1).
* A value less than or equal to zero means use all latent variables.
* (default = 0.95)
*
* -A
* Maximum number of attributes to include in
* transformed attribute names. (-1 = include all)
*
*
* @author Amri Napolitano
* @version $Revision: 8108 $
*/
public class LatentSemanticAnalysis
extends UnsupervisedAttributeEvaluator
implements AttributeTransformer, OptionHandler {
/** For serialization */
static final long serialVersionUID = -8712112988018106198L;
/** The data to transform analyse/transform */
private Instances m_trainInstances;
/**
* Keep a copy for the class attribute (if set) and for
* checking for header compatibility
*/
private Instances m_trainHeader;
/** The header for the transformed data format */
private Instances m_transformedFormat;
/** Data has a class set */
private boolean m_hasClass;
/** Class index */
private int m_classIndex;
/** Number of attributes */
private int m_numAttributes;
/** Number of instances */
private int m_numInstances;
/** Is transpose necessary because numAttributes < numInstances? */
private boolean m_transpose = false;
/** Will hold the left singular vectors */
private Matrix m_u = null;
/** Will hold the singular values */
private Matrix m_s = null;
/** Will hold the right singular values */
private Matrix m_v = null;
/** Will hold the matrix used to transform instances to the new feature space */
private Matrix m_transformationMatrix = null;
/** Filters for original data */
private ReplaceMissingValues m_replaceMissingFilter;
private Normalize m_normalizeFilter;
private NominalToBinary m_nominalToBinaryFilter;
private Remove m_attributeFilter;
/** The number of attributes in the LSA transformed data */
private int m_outputNumAttributes = -1;
/** Normalize the input data? */
private boolean m_normalize = false;
/** The approximation rank to use (between 0 and 1 means coverage proportion) */
private double m_rank = 0.95;
/** The sum of the squares of the singular values */
private double m_sumSquaredSingularValues = 0.0;
/** The actual rank number to use for computation */
private int m_actualRank = -1;
/** Maximum number of attributes in the transformed attribute name */
private int m_maxAttributesInName = 5;
/**
* Returns a string describing this attribute transformer
* @return a description of the evaluator suitable for
* displaying in the explorer/experimenter gui
*/
public String globalInfo() {
return "Performs latent semantic analysis and transformation of the data. Use in " +
"conjunction with a Ranker search. A low-rank approximation of the full data is " +
"found by either specifying the number of singular values to use or specifying a " +
"proportion of the singular values to cover.";
}
/**
* Returns an enumeration describing the available options.
*
* @return an enumeration of all the available options.
**/
public Enumeration listOptions () {
Vector options = new Vector(4);
options.addElement(new Option("\tNormalize input data.", "N", 0, "-N"));
options.addElement(new Option("\tRank approximation used in LSA. \n" +
"\tMay be actual number of LSA attributes \n" +
"\tto include (if greater than 1) or a \n" +
"\tproportion of total singular values to \n" +
"\taccount for (if between 0 and 1). \n" +
"\tA value less than or equal to zero means \n" +
"\tuse all latent variables.(default = 0.95)",
"R",1,"-R"));
options.addElement(new Option("\tMaximum number of attributes to include\n" +
"\tin transformed attribute names.\n" +
"\t(-1 = include all)"
, "A", 1, "-A"));
return options.elements();
}
/**
* Parses a given list of options.
*
* Valid options are:
*
* -N
* Normalize input data.
*
* -R
* Rank approximation used in LSA. May be actual number of
* LSA attributes to include (if greater than 1) or a proportion
* of total singular values to account for (if between 0 and 1).
* A value less than or equal to zero means use all latent variables.
* (default = 0.95)
*
* -A
* Maximum number of attributes to include in
* transformed attribute names. (-1 = include all)
*
*
* @param options the list of options as an array of strings
* @throws Exception if an option is not supported
*/
public void setOptions (String[] options)
throws Exception {
resetOptions();
String optionString;
//set approximation rank
optionString = Utils.getOption('R', options);
if (optionString.length() != 0) {
double temp;
temp = Double.valueOf(optionString).doubleValue();
setRank(temp);
}
//set number of attributes to use in transformed names
optionString = Utils.getOption('A', options);
if (optionString.length() != 0) {
setMaximumAttributeNames(Integer.parseInt(optionString));
}
//set normalize option
setNormalize(Utils.getFlag('N', options));
}
/**
* Reset to defaults
*/
private void resetOptions() {
m_rank = 0.95;
m_normalize = true;
m_maxAttributesInName = 5;
}
/**
* Returns the tip text for this property
* @return tip text for this property suitable for
* displaying in the explorer/experimenter gui
*/
public String normalizeTipText() {
return "Normalize input data.";
}
/**
* Set whether input data will be normalized.
* @param newNormalize true if input data is to be normalized
*/
public void setNormalize(boolean newNormalize) {
m_normalize = newNormalize;
}
/**
* Gets whether or not input data is to be normalized
* @return true if input data is to be normalized
*/
public boolean getNormalize() {
return m_normalize;
}
/**
* Returns the tip text for this property
* @return tip text for this property suitable for
* displaying in the explorer/experimenter gui
*/
public String rankTipText() {
return "Matrix rank to use for data reduction. Can be a" +
" proportion to indicate desired coverage";
}
/**
* Sets the desired matrix rank (or coverage proportion) for feature-space reduction
* @param newRank the desired rank (or coverage) for feature-space reduction
*/
public void setRank(double newRank) {
m_rank = newRank;
}
/**
* Gets the desired matrix rank (or coverage proportion) for feature-space reduction
* @return the rank (or coverage) for feature-space reduction
*/
public double getRank() {
return m_rank;
}
/**
* Returns the tip text for this property
* @return tip text for this property suitable for
* displaying in the explorer/experimenter gui
*/
public String maximumAttributeNamesTipText() {
return "The maximum number of attributes to include in transformed attribute names.";
}
/**
* Sets maximum number of attributes to include in
* transformed attribute names.
* @param newMaxAttributes the maximum number of attributes
*/
public void setMaximumAttributeNames(int newMaxAttributes) {
m_maxAttributesInName = newMaxAttributes;
}
/**
* Gets maximum number of attributes to include in
* transformed attribute names.
* @return the maximum number of attributes
*/
public int getMaximumAttributeNames() {
return m_maxAttributesInName;
}
/**
* Gets the current settings of LatentSemanticAnalysis
*
* @return an array of strings suitable for passing to setOptions()
*/
public String[] getOptions () {
String[] options = new String[5];
int current = 0;
if (getNormalize()) {
options[current++] = "-N";
}
options[current++] = "-R";
options[current++] = "" + getRank();
options[current++] = "-A";
options[current++] = "" + getMaximumAttributeNames();
while (current < options.length) {
options[current++] = "";
}
return options;
}
/**
* Returns the capabilities of this evaluator.
*
* @return the capabilities of this evaluator
* @see Capabilities
*/
public Capabilities getCapabilities() {
Capabilities result = super.getCapabilities();
result.disableAll();
// attributes
result.enable(Capability.NOMINAL_ATTRIBUTES);
result.enable(Capability.NUMERIC_ATTRIBUTES);
result.enable(Capability.DATE_ATTRIBUTES);
result.enable(Capability.MISSING_VALUES);
// class
result.enable(Capability.NOMINAL_CLASS);
result.enable(Capability.NUMERIC_CLASS);
result.enable(Capability.DATE_CLASS);
result.enable(Capability.MISSING_CLASS_VALUES);
result.enable(Capability.NO_CLASS);
return result;
}
/**
* Initializes the singular values/vectors and performs the analysis
* @param data the instances to analyse/transform
* @throws Exception if analysis fails
*/
public void buildEvaluator(Instances data) throws Exception {
// can evaluator handle data?
getCapabilities().testWithFail(data);
buildAttributeConstructor(data);
}
/**
* Initializes the singular values/vectors and performs the analysis
* @param data the instances to analyse/transform
* @throws Exception if analysis fails
*/
private void buildAttributeConstructor (Instances data) throws Exception {
// initialize attributes for performing analysis
m_transpose = false;
m_s = null;
m_u = null;
m_v = null;
m_outputNumAttributes = -1;
m_actualRank = -1;
m_sumSquaredSingularValues = 0.0;
m_trainInstances = new Instances(data);
m_trainHeader = null;
m_attributeFilter = null;
m_nominalToBinaryFilter = null;
m_replaceMissingFilter = new ReplaceMissingValues();
m_replaceMissingFilter.setInputFormat(m_trainInstances);
m_trainInstances = Filter.useFilter(m_trainInstances, m_replaceMissingFilter);
// vector to hold indices of attributes to delete (class attribute,
// attributes that are all missing, or attributes with one distinct value)
Vector attributesToRemove = new Vector();
// if data has a class attribute
if (m_trainInstances.classIndex() >= 0) {
m_hasClass = true;
m_classIndex = m_trainInstances.classIndex();
// set class attribute to be removed
attributesToRemove.addElement(new Integer(m_classIndex));
}
// make copy of training data so the class values (if set) can be appended to final
// transformed instances and so that we can check header compatibility
m_trainHeader = new Instances(m_trainInstances, 0);
// normalize data if desired
if (m_normalize) {
m_normalizeFilter = new Normalize();
m_normalizeFilter.setInputFormat(m_trainInstances);
m_trainInstances = Filter.useFilter(m_trainInstances, m_normalizeFilter);
}
// convert any nominal attributes to binary numeric attributes
m_nominalToBinaryFilter = new NominalToBinary();
m_nominalToBinaryFilter.setInputFormat(m_trainInstances);
m_trainInstances = Filter.useFilter(m_trainInstances, m_nominalToBinaryFilter);
// delete any attributes with only one distinct value or are all missing
for (int i = 0; i < m_trainInstances.numAttributes(); i++) {
if (m_trainInstances.numDistinctValues(i) <= 1) {
attributesToRemove.addElement(new Integer(i));
}
}
// remove columns from the data if necessary
if (attributesToRemove.size() > 0) {
m_attributeFilter = new Remove();
int [] todelete = new int[attributesToRemove.size()];
for (int i = 0; i < attributesToRemove.size(); i++) {
todelete[i] = ((Integer)(attributesToRemove.elementAt(i))).intValue();
}
m_attributeFilter.setAttributeIndicesArray(todelete);
m_attributeFilter.setInvertSelection(false);
m_attributeFilter.setInputFormat(m_trainInstances);
m_trainInstances = Filter.useFilter(m_trainInstances, m_attributeFilter);
}
// can evaluator handle the processed data ? e.g., enough attributes?
getCapabilities().testWithFail(m_trainInstances);
// record properties of final, ready-to-process data
m_numInstances = m_trainInstances.numInstances();
m_numAttributes = m_trainInstances.numAttributes();
// create matrix of attribute values and compute singular value decomposition
double [][] trainValues = new double[m_numAttributes][m_numInstances];
for (int i = 0; i < m_numAttributes; i++) {
trainValues[i] = m_trainInstances.attributeToDoubleArray(i);
}
Matrix trainMatrix = new Matrix(trainValues);
// svd requires rows >= columns, so transpose data if necessary
if (m_numAttributes < m_numInstances) {
m_transpose = true;
trainMatrix = trainMatrix.transpose();
}
SingularValueDecomposition trainSVD = trainMatrix.svd();
m_u = trainSVD.getU(); // left singular vectors
m_s = trainSVD.getS(); // singular values
m_v = trainSVD.getV(); // right singular vectors
// find actual rank to use
int maxSingularValues = trainSVD.rank();
for (int i = 0; i < m_s.getRowDimension(); i++) {
m_sumSquaredSingularValues += m_s.get(i, i) * m_s.get(i, i);
}
if (maxSingularValues == 0) { // no nonzero singular values (shouldn't happen)
// reset values from computation
m_s = null;
m_u = null;
m_v = null;
m_sumSquaredSingularValues = 0.0;
throw new Exception("SVD computation produced no non-zero singular values.");
}
if (m_rank > maxSingularValues || m_rank <= 0) { // adjust rank if too high or too low
m_actualRank = maxSingularValues;
} else if (m_rank < 1.0) { // determine how many singular values to include for desired coverage
double currentSumOfSquaredSingularValues = 0.0;
for (int i = 0; i < m_s.getRowDimension() && m_actualRank == -1; i++) {
currentSumOfSquaredSingularValues += m_s.get(i, i) * m_s.get(i, i);
if (currentSumOfSquaredSingularValues / m_sumSquaredSingularValues >= m_rank) {
m_actualRank = i + 1;
}
}
} else {
m_actualRank = (int) m_rank;
}
// lower matrix ranks, adjust for transposition (if necessary), and
// compute matrix for transforming future instances
if (m_transpose) {
Matrix tempMatrix = m_u;
m_u = m_v;
m_v = tempMatrix;
}
m_u = m_u.getMatrix(0, m_u.getRowDimension() - 1, 0, m_actualRank - 1);
m_s = m_s.getMatrix(0, m_actualRank - 1, 0, m_actualRank - 1);
m_v = m_v.getMatrix(0, m_v.getRowDimension() - 1, 0, m_actualRank - 1);
m_transformationMatrix = m_u.times(m_s.inverse());
//create dataset header for transformed instances
m_transformedFormat = setOutputFormat();
}
/**
* Set the format for the transformed data
* @return a set of empty Instances (header only) in the new format
*/
private Instances setOutputFormat() {
// if analysis hasn't been performed (successfully) yet
if (m_s == null) {
return null;
}
// set up transformed attributes
if (m_hasClass) {
m_outputNumAttributes = m_actualRank + 1;
} else {
m_outputNumAttributes = m_actualRank;
}
int numAttributesInName = m_maxAttributesInName;
if (numAttributesInName <= 0 || numAttributesInName >= m_numAttributes) {
numAttributesInName = m_numAttributes;
}
FastVector attributes = new FastVector(m_outputNumAttributes);
for (int i = 0; i < m_actualRank; i++) {
// create attribute name
String attributeName = "";
double [] attributeCoefficients =
m_transformationMatrix.getMatrix(0, m_numAttributes - 1, i, i).getColumnPackedCopy();
for (int j = 0; j < numAttributesInName; j++) {
if (j > 0) {
attributeName += "+";
}
attributeName += Utils.doubleToString(attributeCoefficients[j], 5, 3);
attributeName += m_trainInstances.attribute(j).name();
}
if (numAttributesInName < m_numAttributes) {
attributeName += "...";
}
// add attribute
attributes.addElement(new Attribute(attributeName));
}
// add original class attribute if present
if (m_hasClass) {
attributes.addElement(m_trainHeader.classAttribute().copy());
}
// create blank header
Instances outputFormat = new Instances(m_trainInstances.relationName() + "_LSA",
attributes, 0);
m_outputNumAttributes = outputFormat.numAttributes();
// set class attribute if applicable
if (m_hasClass) {
outputFormat.setClassIndex(m_outputNumAttributes - 1);
}
return outputFormat;
}
/**
* 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().
* @return the header of the transformed data.
* @throws Exception if the header of the transformed data can't
* be determined.
*/
public Instances transformedHeader() throws Exception {
if (m_s == null) {
throw new Exception("Latent Semantic Analysis hasn't been successfully performed.");
}
return m_transformedFormat;
}
/**
* Transform the supplied data set (assumed to be the same format
* as the training data)
* @return the transformed training data
* @throws Exception if transformed data can't be returned
*/
public Instances transformedData(Instances data) throws Exception {
if (m_s == null) {
throw new Exception("Latent Semantic Analysis hasn't been built yet");
}
Instances output = new Instances(m_transformedFormat, m_numInstances);
// the transformed version of instance i from the training data
// is stored as the i'th row vector in v (the right singular vectors)
for (int i = 0; i < data.numInstances(); i++) {
Instance currentInstance = data.instance(i);
// record attribute values for converted instance
double [] newValues = new double[m_outputNumAttributes];
for (int j = 0; j < m_actualRank; j++) { // fill in values from v
newValues[j] = m_v.get(i, j);
}
if (m_hasClass) { // copy class value if applicable
newValues[m_outputNumAttributes - 1] = currentInstance.classValue();
}
//create new instance with recorded values and add to output dataset
Instance newInstance;
if (currentInstance instanceof SparseInstance) {
newInstance = new SparseInstance(currentInstance.weight(), newValues);
} else {
newInstance = new DenseInstance(currentInstance.weight(), newValues);
}
output.add(newInstance);
}
return output;
}
/**
* Evaluates the merit of a transformed attribute. This is defined
* to be the square of the singular value for the latent variable
* corresponding to the transformed attribute.
* @param att the attribute to be evaluated
* @return the merit of a transformed attribute
* @throws Exception if attribute can't be evaluated
*/
public double evaluateAttribute(int att) throws Exception {
if (m_s == null) {
throw new Exception("Latent Semantic Analysis hasn't been successfully" +
" performed yet!");
}
//return the square of the corresponding singular value
return (m_s.get(att, att) * m_s.get(att, att)) / m_sumSquaredSingularValues;
}
/**
* Transform an instance in original (unnormalized) format
* @param instance an instance in the original (unnormalized) format
* @return a transformed instance
* @throws Exception if instance can't be transformed
*/
public Instance convertInstance(Instance instance) throws Exception {
if (m_s == null) {
throw new Exception("convertInstance: Latent Semantic Analysis not " +
"performed yet.");
}
// array to hold new attribute values
double [] newValues = new double[m_outputNumAttributes];
// apply filters so new instance is in same format as training instances
Instance tempInstance = (Instance)instance.copy();
if (!instance.dataset().equalHeaders(m_trainHeader)) {
throw new Exception("Can't convert instance: headers don't match: " +
"LatentSemanticAnalysis\n" + instance.dataset().equalHeadersMsg(m_trainHeader));
}
// replace missing values
m_replaceMissingFilter.input(tempInstance);
m_replaceMissingFilter.batchFinished();
tempInstance = m_replaceMissingFilter.output();
// normalize
if (m_normalize) {
m_normalizeFilter.input(tempInstance);
m_normalizeFilter.batchFinished();
tempInstance = m_normalizeFilter.output();
}
// convert nominal attributes to binary
m_nominalToBinaryFilter.input(tempInstance);
m_nominalToBinaryFilter.batchFinished();
tempInstance = m_nominalToBinaryFilter.output();
// remove class/other attributes
if (m_attributeFilter != null) {
m_attributeFilter.input(tempInstance);
m_attributeFilter.batchFinished();
tempInstance = m_attributeFilter.output();
}
// record new attribute values
if (m_hasClass) { // copy class value
newValues[m_outputNumAttributes - 1] = instance.classValue();
}
double [][] oldInstanceValues = new double[1][m_numAttributes];
oldInstanceValues[0] = tempInstance.toDoubleArray();
Matrix instanceVector = new Matrix(oldInstanceValues); // old attribute values
instanceVector = instanceVector.times(m_transformationMatrix); // new attribute values
for (int i = 0; i < m_actualRank; i++) {
newValues[i] = instanceVector.get(0, i);
}
// return newly transformed instance
if (instance instanceof SparseInstance) {
return new SparseInstance(instance.weight(), newValues);
} else {
return new DenseInstance(instance.weight(), newValues);
}
}
/**
* Returns a description of this attribute transformer
* @return a String describing this attribute transformer
*/
public String toString() {
if (m_s == null) {
return "Latent Semantic Analysis hasn't been built yet!";
} else {
return "\tLatent Semantic Analysis Attribute Transformer\n\n"
+ lsaSummary();
}
}
/**
* Return a summary of the analysis
* @return a summary of the analysis.
*/
private String lsaSummary() {
StringBuffer result = new StringBuffer();
// print number of latent variables used
result.append("Number of latent variables utilized: " + m_actualRank);
// print singular values
result.append("\n\nSingularValue\tLatentVariable#\n");
// create single array of singular values rather than diagonal matrix
for (int i = 0; i < m_actualRank; i++) {
result.append(Utils.doubleToString(m_s.get(i, i), 9, 5) + "\t" + (i + 1) + "\n");
}
// print attribute vectors
result.append("\nAttribute vectors (left singular vectors) -- row vectors show\n" +
"the relation between the original attributes and the latent \n" +
"variables computed by the singular value decomposition:\n");
for (int i = 0; i < m_actualRank; i++) {
result.append("LatentVariable#" + (i + 1) + "\t");
}
result.append("AttributeName\n");
for (int i = 0; i < m_u.getRowDimension(); i++) { // for each attribute
for (int j = 0; j < m_u.getColumnDimension(); j++) { // for each latent variable
result.append(Utils.doubleToString(m_u.get(i, j), 9, 5) + "\t\t");
}
result.append(m_trainInstances.attribute(i).name() + "\n");
}
// print instance vectors
result.append("\n\nInstance vectors (right singular vectors) -- column\n" +
"vectors show the relation between the original instances and the\n" +
"latent variables computed by the singular value decomposition:\n");
for (int i = 0; i < m_numInstances; i++) {
result.append("Instance#" + (i + 1) + "\t");
}
result.append("LatentVariable#\n");
for (int i = 0; i < m_v.getColumnDimension(); i++) { // for each instance
for (int j = 0; j < m_v.getRowDimension(); j++) { // for each latent variable
// going down columns instead of across rows because we're
// printing v' but have v stored
result.append(Utils.doubleToString(m_v.get(j, i), 9, 5) + "\t");
}
result.append((i + 1) + "\n");
}
return result.toString();
}
/**
* Returns the revision string.
*
* @return the revision
*/
public String getRevision() {
return RevisionUtils.extract("$Revision: 8108 $");
}
/**
* Main method for testing this class
* @param argv should contain the command line arguments to the
* evaluator/transformer (see AttributeSelection)
*/
public static void main(String [] argv) {
runEvaluator(new LatentSemanticAnalysis(), argv);
}
}