org.apache.mahout.utils.vectors.lucene.TFDFMapper.java Source code

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Here is the source code for org.apache.mahout.utils.vectors.lucene.TFDFMapper.java

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/**
 * 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;
    }

}