/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.utils.vectors.lucene;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.TermVectorOffsetInfo;
import org.apache.mahout.matrix.SparseVector;
import org.apache.mahout.matrix.Vector;
import org.apache.mahout.utils.vectors.Weight;
import org.apache.mahout.utils.vectors.TermEntry;
import org.apache.mahout.utils.vectors.TermInfo;
/**
* Not thread-safe
*/
public class TFDFMapper extends VectorMapper {
//public static final int DEFAULT_CACHE_SIZE = 256;
private final IndexReader reader; // TODO never used?
private Vector vector;
private final Weight weight;
private int numTerms;
private final TermInfo termInfo;
private String field;
private final int numDocs;
public TFDFMapper(IndexReader reader, Weight weight, TermInfo termInfo) {
this.reader = reader;
this.weight = weight;
this.termInfo = termInfo;
this.numDocs = reader.numDocs();
}
@Override
public Vector getVector() {
return vector;
}
@Override
public void setExpectations(String field, int numTerms, boolean storeOffsets, boolean storePositions) {
this.field = field;
vector = new SparseVector(termInfo.totalTerms(field));
this.numTerms = numTerms;
}
@Override
public void map(String term, int frequency, TermVectorOffsetInfo[] offsets, int[] positions) {
TermEntry entry = termInfo.getTermEntry(field, term);
if (entry != null) {
vector.setQuick(entry.termIdx, weight.calculate(frequency, entry.docFreq, numTerms, numDocs));
}
}
@Override
public boolean isIgnoringPositions() {
return true;
}
@Override
public boolean isIgnoringOffsets() {
return true;
}
}