/**
* Builds a sparse term-document-like matrix for the provided matrixWordIndices in the same term
* space as the original term-document matrix.
*/
static DoubleMatrix2D buildAlignedMatrix(
VectorSpaceModelContext vsmContext, int[] featureIndex, ITermWeighting termWeighting) {
final IntIntHashMap stemToRowIndex = vsmContext.stemToRowIndex;
if (featureIndex.length == 0) {
return new DenseDoubleMatrix2D(stemToRowIndex.size(), 0);
}
final DoubleMatrix2D phraseMatrix =
new SparseDoubleMatrix2D(stemToRowIndex.size(), featureIndex.length);
final PreprocessingContext preprocessingContext = vsmContext.preprocessingContext;
final int[] wordsStemIndex = preprocessingContext.allWords.stemIndex;
final int[] stemsTf = preprocessingContext.allStems.tf;
final int[][] stemsTfByDocument = preprocessingContext.allStems.tfByDocument;
final int[][] phrasesWordIndices = preprocessingContext.allPhrases.wordIndices;
final int documentCount = preprocessingContext.documents.size();
final int wordCount = wordsStemIndex.length;
for (int i = 0; i < featureIndex.length; i++) {
final int feature = featureIndex[i];
final int[] wordIndices;
if (feature < wordCount) {
wordIndices = new int[] {feature};
} else {
wordIndices = phrasesWordIndices[feature - wordCount];
}
for (int wordIndex = 0; wordIndex < wordIndices.length; wordIndex++) {
final int stemIndex = wordsStemIndex[wordIndices[wordIndex]];
final int index = stemToRowIndex.indexOf(stemIndex);
if (stemToRowIndex.indexExists(index)) {
final int rowIndex = stemToRowIndex.indexGet(index);
double weight =
termWeighting.calculateTermWeight(
stemsTf[stemIndex], stemsTfByDocument[stemIndex].length / 2, documentCount);
phraseMatrix.setQuick(rowIndex, i, weight);
}
}
}
return phraseMatrix;
}
/**
* Builds a term-phrase matrix in the same space as the main term-document matrix. If the
* processing context contains no phrases, {@link VectorSpaceModelContext#termPhraseMatrix} will
* remain <code>null</code>.
*/
public void buildTermPhraseMatrix(VectorSpaceModelContext context) {
final PreprocessingContext preprocessingContext = context.preprocessingContext;
final IntIntHashMap stemToRowIndex = context.stemToRowIndex;
final int[] labelsFeatureIndex = preprocessingContext.allLabels.featureIndex;
final int firstPhraseIndex = preprocessingContext.allLabels.firstPhraseIndex;
if (firstPhraseIndex >= 0 && stemToRowIndex.size() > 0) {
// Build phrase matrix
int[] phraseFeatureIndices = new int[labelsFeatureIndex.length - firstPhraseIndex];
for (int featureIndex = 0; featureIndex < phraseFeatureIndices.length; featureIndex++) {
phraseFeatureIndices[featureIndex] = labelsFeatureIndex[featureIndex + firstPhraseIndex];
}
final DoubleMatrix2D phraseMatrix =
TermDocumentMatrixBuilder.buildAlignedMatrix(
context, phraseFeatureIndices, termWeighting);
MatrixUtils.normalizeColumnL2(phraseMatrix, null);
context.termPhraseMatrix = phraseMatrix.viewDice();
}
}
