redpoll.text.TfIdfReducer.java Source code

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Here is the source code for redpoll.text.TfIdfReducer.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 redpoll.text;

import java.io.IOException;
import java.util.Iterator;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;

import redpoll.core.WritableSparseVector;

/**
 * Reducer to create vsm of documents.
 * @author Jeremy Chow(coderplay@gmail.com)
 */
public class TfIdfReducer extends MapReduceBase implements Reducer<Text, TfIdfWritable, Text, TfIdfWritable> {

    private int totalTerms;

    public void reduce(Text key, Iterator<TfIdfWritable> values, OutputCollector<Text, TfIdfWritable> output,
            Reporter reporter) throws IOException {
        WritableSparseVector tfIdfVector = new WritableSparseVector(totalTerms);
        while (values.hasNext()) {
            ElementWritable value = (ElementWritable) values.next().get();
            tfIdfVector.setQuick(value.getIndex(), value.getValue());
        }

        // tf-idf style vector
        output.collect(key, new TfIdfWritable(tfIdfVector));
    }

    @Override
    public void configure(JobConf job) {
        totalTerms = job.getInt("redpoll.text.terms.num", 1024);
    }

}