Filtering Columns Using MapReduce (Map Only)

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author: Bharat (sree ram)

contact : 04042026071

_____________________________________________________________________________

author :  halitics.blogspot.in (bharat)
input file :  emp.txt

_____________________
101,amar,m,20000,hyd
102,amala,f,30000,pune
103,siva,m,40000,hyd
104,sivani,f,50000,hyd
105,hari,m,40000,pune
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output expected:
only name, salary , and city fields to be written  in output file.

 amar,20000,hyd
amala,30000,pune
siva,40000,hyd
sivani,50000,hyd
hari,40000,pune



package my.map.red;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.fs.Path;

import org.apache.hadoop.io.LongWritable;

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;

import org.apache.hadoop.util.GenericOptionsParser;

public class  FilterColumns{

  public static class Map1 extends Mapper<LongWritable,Text,Text,Text>  {

              public void map(LongWritable k, Text v, Context con) throws IOException, InterruptedException{

                           String line=v.toString();

                           String[] words=line.split(",");

                           String newline = words[1]+","+ words[3]+","+words[4];
                           con.write(new Text(newline), new Text());

              }

  }

  public static void main(String[] args) throws Exception  {

              Configuration c=new Configuration();

              String[] files=new GenericOptionsParser(c,args).getRemainingArgs();

              Path p1=new Path(files[0]);

              Path p2=new Path(files[1]);

              Job j = new Job(c,"FilterColumns");

              j.setJarByClass(FilterColumns.class);

              j.setMapperClass(Map1.class);

              j.setNumReduceTasks(0);

              j.setOutputKeyClass(Text.class);

              j.setOutputValueClass(Text.class);

              FileInputFormat.addInputPath(j,p1);
               FileOutputFormat.setOutputPath(j, p2);

                System.exit(j.waitForCompletion(true) ? 0:1);

             

  }

}