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

java.lang.Object
  extended by org.apache.hadoop.mapred.MapReduceBase
      extended by org.apache.hadoop.mapred.lib.InverseMapper<K,V>
All Implemented Interfaces:
Closeable, JobConfigurable, Mapper<K,V,V,K>

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

A Mapper that swaps keys and values.


Constructor Summary
InverseMapper()
           
 
Method Summary
 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 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


Copyright © 2012 Apache Software Foundation. All Rights Reserved.