org.apache.hadoop.mapred.lib

Class InverseMapper<K,V>

java.lang.Object

org.apache.hadoop.mapred.MapReduceBase

org.apache.hadoop.mapred.lib.InverseMapper<K,V>

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, JobConfigurable, Mapper<K,V,V,K>

public class InverseMapper<K,V>
extends MapReduceBase
implements Mapper<K,V,V,K>

A Mapper that swaps keys and values.

Constructor Summary

Constructors

Constructor and Description
InverseMapper()

Method Summary

Methods

Modifier and Type	Method and Description
void	map(K key, V value, OutputCollector<V,K> output, Reporter reporter) The inverse function.

Methods inherited from class org.apache.hadoop.mapred.MapReduceBase

close, configure

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.mapred.JobConfigurable

configure

Methods inherited from interface java.io.Closeable

close

Constructor Detail

InverseMapper

public InverseMapper()

Method Detail

map

public void map(K key,
       V value,
       OutputCollector<V,K> output,
       Reporter reporter)
         throws java.io.IOException

The inverse function. Input keys and values are swapped.

Specified by:

map in interface Mapper<K,V,V,K>

Parameters:

key - the input key.

value - the input value.

output - collects mapped keys and values.

reporter - facility to report progress.

Throws:

java.io.IOException