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/*
* To change this license header, choose License Headers in Project Properties.
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* and open the template in the editor.
*/
package com.github.milind;
import java.io.IOException;
import java.util.StringTokenizer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
/**
*
* @author milind
*/
public class GlobalNumberAverage {
public static class GlobalNumberAverageMapper
extends Mapper < Object, Text, Text, DoubleWritable > {
int sum = 0;
int count = 0;
public void map(Object key, Text value, Mapper.Context context) throws IOException,
InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
while (itr.hasMoreTokens()) {
String str = itr.nextToken();
sum = sum + Integer.parseInt(str);
count += 1;
}
}
public void cleanup(Mapper.Context context) throws IOException,
InterruptedException {
context.write(new Text("Average of numbers is"), new DoubleWritable(sum / count));
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = Job.getInstance(conf, "Global Average of Numbers");
job.setJarByClass(GlobalNumberAverage.class);
job.setMapperClass(GlobalNumberAverageMapper.class);
job.setNumReduceTasks(0);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(DoubleWritable.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
@milindjagre

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commented May 9, 2016

This MapReduce code will calculate average of all the numbers present in the file.

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