org.apache.crunch.fn

Class MapKeysFn<K1,K2,V>

java.lang.Object

org.apache.crunch.DoFn<Pair<K1,V>,Pair<K2,V>>

org.apache.crunch.fn.MapKeysFn<K1,K2,V>

All Implemented Interfaces:

Serializable

public abstract class MapKeysFn<K1,K2,V>
extends DoFn<Pair<K1,V>,Pair<K2,V>>

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
MapKeysFn()

Method Summary

Methods

Modifier and Type	Method and Description
abstract K2	map(K1 k1)
void	process(Pair<K1,V> input, Emitter<Pair<K2,V>> emitter) Processes the records from a PCollection.

Methods inherited from class org.apache.crunch.DoFn

cleanup, configure, initialize, scaleFactor, setContext

Methods inherited from class java.lang.Object

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

Constructor Detail

MapKeysFn

public MapKeysFn()

Method Detail

process

public void process(Pair<K1,V> input,
           Emitter<Pair<K2,V>> emitter)

Description copied from class: DoFn

Processes the records from a PCollection.

Note: Crunch can reuse a single input record object whose content changes on each DoFn.process(Object, Emitter) method call. This functionality is imposed by Hadoop's Reducer implementation: The framework will reuse the key and value objects that are passed into the reduce, therefore the application should clone the objects they want to keep a copy of.

Specified by:

process in class DoFn<Pair<K1,V>,Pair<K2,V>>

Parameters:

input - The input record.

emitter - The emitter to send the output to

map

public abstract K2 map(K1 k1)