org.apache.mahout.vectorizer.pruner.WordsPrunerReducer.java Source code

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Here is the source code for org.apache.mahout.vectorizer.pruner.WordsPrunerReducer.java

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package org.apache.mahout.vectorizer.pruner;
/**
 * 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.
 */

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.common.HadoopUtil;
import org.apache.mahout.common.Pair;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileIterable;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import org.apache.mahout.math.map.OpenIntLongHashMap;
import org.apache.mahout.vectorizer.HighDFWordsPruner;

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

public class WordsPrunerReducer
        extends Reducer<WritableComparable<?>, VectorWritable, WritableComparable<?>, VectorWritable> {

    private final OpenIntLongHashMap dictionary = new OpenIntLongHashMap();
    private long maxDf = Long.MAX_VALUE;
    private long minDf = -1;

    @Override
    protected void reduce(WritableComparable<?> key, Iterable<VectorWritable> values, Context context)
            throws IOException, InterruptedException {
        Iterator<VectorWritable> it = values.iterator();
        if (!it.hasNext()) {
            return;
        }
        Vector value = it.next().get();
        Vector vector = value.clone();
        if (maxDf != Long.MAX_VALUE || minDf > -1) {
            for (Vector.Element e : value.nonZeroes()) {
                if (!dictionary.containsKey(e.index())) {
                    vector.setQuick(e.index(), 0.0);
                    continue;
                }
                long df = dictionary.get(e.index());
                if (df > maxDf || df < minDf) {
                    vector.setQuick(e.index(), 0.0);
                }
            }
        }

        VectorWritable vectorWritable = new VectorWritable(vector);
        context.write(key, vectorWritable);
    }

    @Override
    protected void setup(Context context) throws IOException, InterruptedException {
        super.setup(context);
        Configuration conf = context.getConfiguration();
        //Path[] localFiles = HadoopUtil.getCachedFiles(conf);

        maxDf = conf.getLong(HighDFWordsPruner.MAX_DF, Long.MAX_VALUE);
        minDf = conf.getLong(HighDFWordsPruner.MIN_DF, -1);

        Path dictionaryFile = HadoopUtil.getSingleCachedFile(conf);

        // key is feature, value is the document frequency
        for (Pair<IntWritable, LongWritable> record : new SequenceFileIterable<IntWritable, LongWritable>(
                dictionaryFile, true, conf)) {
            dictionary.put(record.getFirst().get(), record.getSecond().get());
        }
    }
}