org.apache.crunch.lambda

Class LAggregator<V,A>

java.lang.Object

org.apache.crunch.fn.Aggregators.SimpleAggregator<V>

org.apache.crunch.lambda.LAggregator<V,A>

Type Parameters:

V - Type of values to be aggregated

A - Type of object which stores objects as they are being aggregated

All Implemented Interfaces:

Serializable, Aggregator<V>

public class LAggregator<V,A>
extends Aggregators.SimpleAggregator<V>

Crunch Aggregator expressed as a composition of functional interface implementations

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
LAggregator(SSupplier<A> initialSupplier, SBiFunction<A,V,A> combineFn, SFunction<A,Iterable<V>> outputFn)

Method Summary

Modifier and Type	Method and Description
void	reset() Clears the internal state of this Aggregator and prepares it for the values associated with the next key.
Iterable<V>	results() Returns the current aggregated state of this instance.
void	update(V v) Incorporate the given value into the aggregate state maintained by this instance.

Methods inherited from class org.apache.crunch.fn.Aggregators.SimpleAggregator

initialize

Methods inherited from class java.lang.Object

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

Constructor Detail

LAggregator

public LAggregator(SSupplier<A> initialSupplier,
                   SBiFunction<A,V,A> combineFn,
                   SFunction<A,Iterable<V>> outputFn)

Method Detail

reset

public void reset()

Description copied from interface: Aggregator

Clears the internal state of this Aggregator and prepares it for the values associated with the next key. Depending on what you aggregate, this typically means setting a variable to zero or clearing a list. Failing to do this will yield wrong results!

update

public void update(V v)

Description copied from interface: Aggregator

Incorporate the given value into the aggregate state maintained by this instance.

Parameters:

v - The value to add to the aggregated state

results

public Iterable<V> results()

Description copied from interface: Aggregator

Returns the current aggregated state of this instance.