HI vikas,
You can download example programes from facebook group link below:
http://www.facebook.com/groups/416125741763625/
It contain some ppt as well.
Regards,
Saravanan Nagarajan
On Wed, Jul 25, 2012 at 10:17 AM, minumichael <minumichael.olassa...@tcs.com
> wrote:
>
> Hi Vikas,
>
> You could also try out various examples like finding the maximum
> temperature
> from a given dataset
>
> 0067011990999991950051507004...9999999N9+00001+99999999999...
> 0043011990999991950051512004...9999999N9+00221+99999999999...
> 0043011990999991950051518004...9999999N9-00111+99999999999...
> 0043012650999991949032412004...0500001N9+01111+99999999999...
> 0043012650999991949032418004...0500001N9+00781+99999999999...
>
> //Mapper for maximum temperature example
>
> import java.io.IOException;
> import org.apache.hadoop.io.LongWritable;
> import org.apache.hadoop.io.Text;
> import org.apache.hadoop.mapreduce.Mapper;
>
> public class MaxTemperatureMapper
> extends Mapper<LongWritable, Text, Text, IntWritable> {
> private static final int MISSING = 9999;
> @Override
> public void map(LongWritable key, Text value, Context context)
> throws IOException, InterruptedException {
> }
> }
> String line = value.toString();
> String year = line.substring(15, 19);
> int airTemperature;
> if (line.charAt(87) == '+') { // parseInt doesn't like leading plus signs
> airTemperature = Integer.parseInt(line.substring(88, 92));
> } else {
> airTemperature = Integer.parseInt(line.substring(87, 92));
> }
> String quality = line.substring(92, 93);
> if (airTemperature != MISSING && quality.matches("[01459]")) {
> context.write(new Text(year), new IntWritable(airTemperature));
> }
> }}
> //Reducer for maximum temperature example
> import java.io.IOException;
> import org.apache.hadoop.io.IntWritable;
> import org.apache.hadoop.io.Text;
> import org.apache.hadoop.mapreduce.Reducer;
> public class MaxTemperatureReducer
> extends Reducer<Text, IntWritable, Text, IntWritable> {
> @Override
> public void reduce(Text key, Iterable<IntWritable> values,
> Context context)
> throws IOException, InterruptedException {
> }
> }
> int maxValue = Integer.MIN_VALUE;
> for (IntWritable value : values) {
> maxValue = Math.max(maxValue, value.get());
> }
> context.write(key, new IntWritable(maxValue));
> }
> }
> //Application to find the maximum temperature in the weather dataset
> import org.apache.hadoop.fs.Path;
> import org.apache.hadoop.io.IntWritable;
> import org.apache.hadoop.io.Text;
> import org.apache.hadoop.mapreduce.Job;
> import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
> import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
> public class MaxTemperature {
> public static void main(String[] args) throws Exception {
> if (args.length != 2) {
> System.err.println("Usage: MaxTemperature <input path> <output path>");
> System.exit(-1);
> }
> Job job = new Job();
> job.setJarByClass(MaxTemperature.class);
> job.setJobName("Max temperature");
> FileInputFormat.addInputPath(job, new Path(args[0]));
> FileOutputFormat.setOutputPath(job, new Path(args[1]));
> job.setMapperClass(MaxTemperatureMapper.class);
> job.setReducerClass(MaxTemperatureReducer.class);
> job.setOutputKeyClass(Text.class);
> job.setOutputValueClass(IntWritable.class);
> }
> }
> System.exit(job.waitForCompletion(true) ? 0 : 1);
> }
> }
>
> --
> View this message in context:
> http://old.nabble.com/Hadoop-Example-in-java-tp33341353p34208568.html
> Sent from the Hadoop core-user mailing list archive at Nabble.com.
>
>
