DistribCountingMapper.java Source code

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Here is the source code for DistribCountingMapper.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.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.StringTokenizer;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;

import com.google.common.collect.Sets;

public class DistribCountingMapper extends MapReduceBase implements Mapper<LongWritable, Text, Text, IntWritable> {
    @Override
    public void map(LongWritable lineNum, Text value, OutputCollector<Text, IntWritable> output, Reporter reporter)
            throws IOException {
        IntWritable one = new IntWritable(1);
        HashSet<String> transactionItems = new HashSet<String>();
        StringTokenizer st = new StringTokenizer(value.toString());
        while (st.hasMoreTokens()) {
            transactionItems.add(st.nextToken());
        }

        Set<Set<String>> powerSet = Sets.powerSet(transactionItems);
        for (Set<String> itemset : powerSet) {
            if (itemset.size() > 0) {
                String[] itemsetArr = new String[itemset.size()];
                itemset.toArray(itemsetArr);
                Arrays.sort(itemsetArr);
                String itemsetStr = "";
                for (int i = 0; i < itemsetArr.length; i++) {
                    itemsetStr += itemsetArr[i] + " ";
                }
                output.collect(new Text(itemsetStr), one);
            }
        }
    }
}