Package 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:

Closeable, AutoCloseable, Closeable, JobConfigurable, Mapper<K,V,V,K>

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

A Mapper that swaps keys and values.

Constructor Summary

Constructors

Constructor	Description
InverseMapper()

Method Summary

Modifier and Type	Method	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 java.io.Closeable

close

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

configure

Constructor Details

InverseMapper

public InverseMapper()

Method Details

map

public void map(K key,
 V value,
 OutputCollector<V,K> output,
 Reporter reporter)
         throws 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:

IOException