org.unigram.likelike.lsh.SelectClustersReducer.java Source code

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Here is the source code for org.unigram.likelike.lsh.SelectClustersReducer.java

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/**
 * Copyright 2009 Takahiko Ito
 * 
 * 
 * Licensed 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.unigram.likelike.lsh;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.Mapper.Context;

import org.unigram.likelike.common.LikelikeConstants;
import org.unigram.likelike.common.RelatedUsersWritable;
import org.unigram.likelike.common.SeedClusterId;

/**
 * SelectClustersReducer. 
 */
public class SelectClustersReducer
        extends Reducer<SeedClusterId, RelatedUsersWritable, SeedClusterId, RelatedUsersWritable> {

    /**
     * Reduce.
     *
     * @param key cluster id
     * @param values user names
     * @param context -
     * @throws IOException -
     * @throws InterruptedException -
     */
    @Override
    public void reduce(final SeedClusterId key, final Iterable<RelatedUsersWritable> values, final Context context)
            throws IOException, InterruptedException {

        List<LongWritable> ids = new ArrayList<LongWritable>();

        for (RelatedUsersWritable relatedUsers : values) {
            List<LongWritable> tmpUsers = relatedUsers.getRelatedUsers();
            ids.addAll(tmpUsers);
            if (ids.size() >= this.maximumClusterSize) {
                break;
            }
        }
        if (this.minimumClusterSize <= ids.size()) {
            context.write(key, new RelatedUsersWritable(ids));
        }
    }

    /**
     * setup.
     * @param context -
     */
    @Override
    public final void setup(final Context context) {
        Configuration jc = context.getConfiguration();
        if (context == null || jc == null) {
            jc = new Configuration();
        }
        this.maximumClusterSize = jc.getLong(LikelikeConstants.MAX_CLUSTER_SIZE,
                LikelikeConstants.DEFAULT_MAX_CLUSTER_SIZE);
        this.minimumClusterSize = jc.getLong(LikelikeConstants.MIN_CLUSTER_SIZE,
                LikelikeConstants.DEFAULT_MIN_CLUSTER_SIZE);
    }

    /** maximum number of examples in a cluster. */
    private long maximumClusterSize;

    /** minimum number of examples in a cluster. */
    private long minimumClusterSize;
}