org.apache.crunch

Interface PGroupedTable<K,V>

All Superinterfaces:

PCollection<Pair<K,Iterable<V>>>

public interface PGroupedTable<K,V>
extends PCollection<Pair<K,Iterable<V>>>

The Crunch representation of a grouped PTable.

Method Summary

Methods

Modifier and Type	Method and Description
PTable<K,V>	combineValues(Aggregator<V> aggregator) Combine the values in each group using the given Aggregator.
PTable<K,V>	combineValues(CombineFn<K,V> combineFn) Combines the values of this grouping using the given CombineFn.
PTable<K,V>	ungroup() Convert this grouping back into a multimap.

Methods inherited from interface org.apache.crunch.PCollection

asCollection, by, by, count, filter, filter, getName, getPipeline, getPType, getSize, getTypeFamily, length, materialize, max, min, parallelDo, parallelDo, parallelDo, parallelDo, parallelDo, parallelDo, union, write, write

Method Detail

combineValues

PTable<K,V> combineValues(CombineFn<K,V> combineFn)

Combines the values of this grouping using the given CombineFn.

Parameters:

combineFn - The combiner function

Returns:

A PTable where each key has a single value

combineValues

PTable<K,V> combineValues(Aggregator<V> aggregator)

Combine the values in each group using the given Aggregator.

Parameters:

aggregator - The function to use

Returns:

A PTable where each group key maps to an aggregated value. Group keys may be repeated if an aggregator returns more than one value.

ungroup

PTable<K,V> ungroup()

Convert this grouping back into a multimap.

Returns:

an ungrouped version of the data in this PGroupedTable.