org.apache.hadoop.examples

Class WordStandardDeviation.WordStandardDeviationReducer

java.lang.Object

org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable>

org.apache.hadoop.examples.WordStandardDeviation.WordStandardDeviationReducer

Enclosing class:

WordStandardDeviation

public static class WordStandardDeviation.WordStandardDeviationReducer
extends org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable>

Performs integer summation of all the values for each key.

Nested Class Summary

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

org.apache.hadoop.mapreduce.Reducer.Context

Constructor Summary

Constructors

Constructor and Description
WordStandardDeviation.WordStandardDeviationReducer()

Method Summary

Methods

Modifier and Type	Method and Description
void	reduce(org.apache.hadoop.io.Text key, Iterable<org.apache.hadoop.io.LongWritable> values, org.apache.hadoop.mapreduce.Reducer.Context context) Sums all the individual values within the iterator and writes them to the same key.

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

cleanup, run, setup

Methods inherited from class java.lang.Object

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

Constructor Detail

WordStandardDeviation.WordStandardDeviationReducer

public WordStandardDeviation.WordStandardDeviationReducer()

Method Detail

reduce

public void reduce(org.apache.hadoop.io.Text key,
          Iterable<org.apache.hadoop.io.LongWritable> values,
          org.apache.hadoop.mapreduce.Reducer.Context context)
            throws IOException,
                   InterruptedException

Sums all the individual values within the iterator and writes them to the same key.

Overrides:

reduce in class org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.Text,org.apache.hadoop.io.LongWritable>

Parameters:

key - This will be one of 2 constants: LENGTH_STR, COUNT_STR, or SQUARE_STR.

values - This will be an iterator of all the values associated with that key.

Throws:

IOException

InterruptedException