org.apache.mahout.clustering.minhash.MinHashReducer.java Source code

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Here is the source code for org.apache.mahout.clustering.minhash.MinHashReducer.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.clustering.minhash;

import com.google.common.collect.Lists;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.common.commandline.MinhashOptionCreator;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;

import java.io.IOException;
import java.util.Collection;

public class MinHashReducer extends Reducer<Text, Writable, Text, Writable> {

    private int minClusterSize;
    private boolean debugOutput;

    enum Clusters {
        ACCEPTED, DISCARDED
    }

    @Override
    protected void setup(Context context) throws IOException, InterruptedException {
        super.setup(context);
        Configuration conf = context.getConfiguration();
        this.minClusterSize = conf.getInt(MinhashOptionCreator.MIN_CLUSTER_SIZE, 5);
        this.debugOutput = conf.getBoolean(MinhashOptionCreator.DEBUG_OUTPUT, false);
    }

    /**
     * output the items clustered
     */
    @Override
    protected void reduce(Text cluster, Iterable<Writable> points, Context context)
            throws IOException, InterruptedException {
        Collection<Writable> pointList = Lists.newArrayList();
        for (Writable point : points) {
            if (debugOutput) {
                Vector pointVector = ((VectorWritable) point).get().clone();
                Writable writablePointVector = new VectorWritable(pointVector);
                pointList.add(writablePointVector);
            } else {
                Writable pointText = new Text(point.toString());
                pointList.add(pointText);
            }
        }
        if (pointList.size() >= minClusterSize) {
            context.getCounter(Clusters.ACCEPTED).increment(1);
            for (Writable point : pointList) {
                context.write(cluster, point);
            }
        } else {
            context.getCounter(Clusters.DISCARDED).increment(1);
        }
    }

}