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org.apache.crunch.lib
Class Aggregate.TopKCombineFn<K,V>

java.lang.Object
  org.apache.crunch.DoFn<Pair<S,Iterable<T>>,Pair<S,T>>
      org.apache.crunch.CombineFn<Integer,Pair<K,V>>
          org.apache.crunch.lib.Aggregate.TopKCombineFn<K,V>

All Implemented Interfaces:

Serializable

Enclosing class:

Aggregate

public static class Aggregate.TopKCombineFn<K,V>
extends CombineFn<Integer,Pair<K,V>>

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.crunch.CombineFn

CombineFn.Aggregator<T>, CombineFn.AggregatorCombineFn<K,V>, CombineFn.AggregatorFactory<T>, CombineFn.FirstNAggregator<V>, CombineFn.LastNAggregator<V>, CombineFn.MaxBigInts, CombineFn.MaxDoubles, CombineFn.MaxFloats, CombineFn.MaxInts, CombineFn.MaxLongs, CombineFn.MaxNAggregator<V extends Comparable<V>>, CombineFn.MinBigInts, CombineFn.MinDoubles, CombineFn.MinFloats, CombineFn.MinInts, CombineFn.MinLongs, CombineFn.MinNAggregator<V extends Comparable<V>>, CombineFn.PairAggregator<V1,V2>, CombineFn.QuadAggregator<A,B,C,D>, CombineFn.SimpleAggregator<T>, CombineFn.StringConcatAggregator, CombineFn.SumBigInts, CombineFn.SumDoubles, CombineFn.SumFloats, CombineFn.SumInts, CombineFn.SumLongs, CombineFn.TripAggregator<A,B,C>, CombineFn.TupleNAggregator

Field Summary

Fields inherited from class org.apache.crunch.CombineFn

MAX_BIGINTS, MAX_DOUBLES, MAX_FLOATS, MAX_INTS, MAX_LONGS, MIN_BIGINTS, MIN_DOUBLES, MIN_FLOATS, MIN_INTS, MIN_LONGS, SUM_BIGINTS, SUM_DOUBLES, SUM_FLOATS, SUM_INTS, SUM_LONGS

Constructor Summary

Aggregate.TopKCombineFn(int limit, boolean maximize)

Method Summary

void	process(Pair<Integer,Iterable<Pair<K,V>>> input, Emitter<Pair<Integer,Pair<K,V>>> emitter) Processes the records from a PCollection.

Methods inherited from class org.apache.crunch.CombineFn

aggregator, aggregatorFactory, FIRST_N, LAST_N, MAX_BIGINTS, MAX_BIGINTS, MAX_DOUBLES, MAX_DOUBLES, MAX_FLOATS, MAX_FLOATS, MAX_INTS, MAX_INTS, MAX_LONGS, MAX_LONGS, MIN_BIGINTS, MIN_BIGINTS, MIN_DOUBLES, MIN_DOUBLES, MIN_FLOATS, MIN_FLOATS, MIN_INTS, MIN_INTS, MIN_LONGS, MIN_LONGS, pairAggregator, quadAggregator, STRING_CONCAT, STRING_CONCAT, SUM_BIGINTS, SUM_DOUBLES, SUM_FLOATS, SUM_INTS, SUM_LONGS, tripAggregator, tupleAggregator

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

Aggregate.TopKCombineFn

public Aggregate.TopKCombineFn(int limit,
                               boolean maximize)

Method Detail

process

public void process(Pair<Integer,Iterable<Pair<K,V>>> input,
                    Emitter<Pair<Integer,Pair<K,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<Integer,Iterable<Pair<K,V>>>,Pair<Integer,Pair<K,V>>>

Parameters:

input - The input record.

emitter - The emitter to send the output to