DistribCountingReducer.java Source code

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Here is the source code for DistribCountingReducer.java

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/*
 * Copyright 2012-14 Justin A. Debrabant <debrabant@cs.brown.edu> and Matteo Riondato <matteo@cs.brown.edu>
 *
 * 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.
 *
 */

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

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.IntWritable;
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;

public class DistribCountingReducer extends MapReduceBase implements Reducer<Text, IntWritable, Text, Text> {
    int minFreqPercent;
    int datasetSize;

    @Override
    public void configure(JobConf conf) {
        minFreqPercent = conf.getInt("DISTRCOUNT.minFreqPercent", 20);
        datasetSize = conf.getInt("DISTRCOUNT.datasetSize", 1000);
    }

    @Override
    public void reduce(Text itemset, Iterator<IntWritable> values, OutputCollector<Text, Text> output,
            Reporter reporter) throws IOException {
        int sum = 0;
        while (values.hasNext()) {
            sum += values.next().get();
        }

        if (sum >= datasetSize * minFreqPercent / 100) {
            double freq = ((double) sum) / datasetSize;
            output.collect(itemset, new Text((new Double(freq)).toString()));
        }
    }
}