org.apache.hadoop.examples

Class WordStandardDeviation.WordStandardDeviationMapper

java.lang.Object

org.apache.hadoop.mapreduce.Mapper<Object,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable>

org.apache.hadoop.examples.WordStandardDeviation.WordStandardDeviationMapper

Enclosing class:

WordStandardDeviation

public static class WordStandardDeviation.WordStandardDeviationMapper
extends org.apache.hadoop.mapreduce.Mapper<Object,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable>

Maps words from line of text into 3 key-value pairs; one key-value pair for counting the word, one for counting its length, and one for counting the square of its length.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Mapper

org.apache.hadoop.mapreduce.Mapper.Context

Constructor Summary

Constructors

Constructor and Description
WordStandardDeviation.WordStandardDeviationMapper()

Method Summary

Methods

Modifier and Type	Method and Description
void	map(Object key, org.apache.hadoop.io.Text value, org.apache.hadoop.mapreduce.Mapper.Context context) Emits 3 key-value pairs for counting the word, its length, and the squares of its length.

Methods inherited from class org.apache.hadoop.mapreduce.Mapper

cleanup, run, setup

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WordStandardDeviation.WordStandardDeviationMapper

public WordStandardDeviation.WordStandardDeviationMapper()

Method Detail

map

public void map(Object key,
       org.apache.hadoop.io.Text value,
       org.apache.hadoop.mapreduce.Mapper.Context context)
         throws IOException,
                InterruptedException

Emits 3 key-value pairs for counting the word, its length, and the squares of its length. Outputs are (Text, LongWritable).

Overrides:

map in class org.apache.hadoop.mapreduce.Mapper<Object,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable>

Parameters:

value - This will be a line of text coming in from our input file.

Throws:

IOException

InterruptedException