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org.apache.crunch.fn
Class ExtractKeyFn<K,V>

java.lang.Object
  org.apache.crunch.DoFn<S,T>
      org.apache.crunch.MapFn<V,Pair<K,V>>
          org.apache.crunch.fn.ExtractKeyFn<K,V>

All Implemented Interfaces:

Serializable

public class ExtractKeyFn<K,V>
extends MapFn<V,Pair<K,V>>

Wrapper function for converting a MapFn into a key-value pair that is used to convert from a PCollection<V> to a PTable<K, V>.

See Also:

Serialized Form

Constructor Summary

ExtractKeyFn(MapFn<V,K> mapFn)

Method Summary

void	initialize() Initialize this DoFn.
Pair<K,V>	map(V input) Maps the given input into an instance of the output type.
void	setContext(org.apache.hadoop.mapreduce.TaskInputOutputContext<?,?,?,?> context) Called during setup to pass the TaskInputOutputContext to this DoFn instance.

Methods inherited from class org.apache.crunch.MapFn

process, scaleFactor

Methods inherited from class org.apache.crunch.DoFn

cleanup, configure, disableDeepCopy

Methods inherited from class java.lang.Object

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

Constructor Detail

ExtractKeyFn

public ExtractKeyFn(MapFn<V,K> mapFn)

Method Detail

setContext

public void setContext(org.apache.hadoop.mapreduce.TaskInputOutputContext<?,?,?,?> context)

Description copied from class: DoFn

Called during setup to pass the TaskInputOutputContext to this DoFn instance.

Overrides:

setContext in class DoFn<V,Pair<K,V>>

initialize

public void initialize()

Description copied from class: DoFn

Initialize this DoFn. This initialization will happen before the actual DoFn.process(Object, Emitter) is triggered. Subclasses may override this method to do appropriate initialization.

Called during the setup of the job instance this DoFn is associated with.

Overrides:

initialize in class DoFn<V,Pair<K,V>>

map

public Pair<K,V> map(V input)

Description copied from class: MapFn

Maps the given input into an instance of the output type.

Specified by:

map in class MapFn<V,Pair<K,V>>