/**
* 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.util.BytesRef;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.utils.vectors.TermEntry;
import org.apache.mahout.utils.vectors.TermInfo;
import org.apache.mahout.vectorizer.Weight;
/**
* Not thread-safe
*/
public class TFDFMapper {
private Vector vector;
private final Weight weight;
private long numTerms;
private final TermInfo termInfo;
private String field;
private final int numDocs;
public TFDFMapper(int numDocs, Weight weight, TermInfo termInfo) {
this.weight = weight;
this.termInfo = termInfo;
this.numDocs = numDocs;
}
public void setExpectations(String field, long numTerms) {
this.field = field;
vector = new RandomAccessSparseVector(termInfo.totalTerms(field));
this.numTerms = numTerms;
}
public void map(BytesRef term, int frequency) {
TermEntry entry = termInfo.getTermEntry(field, term.utf8ToString());
if (entry != null) {
vector.setQuick(entry.getTermIdx(), weight.calculate(frequency, entry.getDocFreq(), (int)numTerms, numDocs));
}
}
public Vector getVector() {
return this.vector;
}
}