CountHistogram.java Source code

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Here is the source code for CountHistogram.java

Source

/*
* Copyright (C) 2011 by Arpit Sud
* See the LICENSE file for Copyright information
*/
import java.io.IOException;
import java.util.*;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.util.*;

public class CountHistogram extends Configured implements Tool {

    public static class Map extends MapReduceBase implements Mapper<LongWritable, Text, IntWritable, IntWritable> {
        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text();

        public void map(LongWritable key, Text value, OutputCollector<IntWritable, IntWritable> collector,
                Reporter reporter) throws IOException {
            String[] tempArray = value.toString().split("\\t");
            IntWritable count = new IntWritable(Integer.parseInt(tempArray[1]));
            collector.collect(count, one);
        }
    }

    public static class Reduce extends MapReduceBase
            implements Reducer<IntWritable, IntWritable, IntWritable, IntWritable> {
        @Override
        public void reduce(IntWritable key, Iterator<IntWritable> values,
                OutputCollector<IntWritable, IntWritable> collector, Reporter reporter) throws IOException {

            int sum = 0;
            while (values.hasNext()) {
                IntWritable value = values.next();
                sum += value.get();
            }
            collector.collect(key, new IntWritable(sum));
        }
    }

    @Override
    public int run(String[] args) throws Exception {
        try {
            JobClient client = new JobClient();
            JobConf job = new JobConf(getConf(), CountHistogram.class);
            job.setJobName("CountHistogram");

            job.setOutputKeyClass(IntWritable.class);
            job.setOutputValueClass(IntWritable.class);

            job.setMapperClass(Map.class);
            job.setReducerClass(Reduce.class);

            job.setInputFormat(TextInputFormat.class);
            job.setOutputFormat(TextOutputFormat.class);

            FileInputFormat.setInputPaths(job, new Path(args[0]));
            FileOutputFormat.setOutputPath(job, new Path(args[1]));

            client.setConf(job);
            JobClient.runJob(job);
        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        }
        return 0;
    }

    public static void main(String[] args) throws Exception {
        int ret = ToolRunner.run(new CountHistogram(), args);
        System.exit(ret);
    }
}