Package org.apache.beam.sdk.values

Class PCollectionTuple

java.lang.Object
org.apache.beam.sdk.values.PCollectionTuple
All Implemented Interfaces:
PInput, POutput
public class PCollectionTuple extends Object implements PInput, POutput
A PCollectionTuple is an immutable tuple of heterogeneously-typed PCollections, "keyed" by TupleTags. A PCollectionTuple can be used as the input or output of a PTransform taking or producing multiple PCollection inputs or outputs that can be of different types, for instance a ParDo with multiple outputs.

A PCollectionTuple can be created and accessed like follows: 


 PCollection<String> pc1 = ...;
 PCollection<Integer> pc2 = ...;
 PCollection<Iterable<String>> pc3 = ...;

 // Create TupleTags for each of the PCollections to put in the
 // PCollectionTuple (the type of the TupleTag enables tracking the
 // static type of each of the PCollections in the PCollectionTuple):
 TupleTag<String> tag1 = new TupleTag<>();
 TupleTag<Integer> tag2 = new TupleTag<>();
 TupleTag<Iterable<String>> tag3 = new TupleTag<>();

 // Create a PCollectionTuple with three PCollections:
 PCollectionTuple pcs =
     PCollectionTuple.of(tag1, pc1)
                     .and(tag2, pc2)
                     .and(tag3, pc3);

 // Create an empty PCollectionTuple:
 Pipeline p = ...;
 PCollectionTuple pcs2 = PCollectionTuple.empty(p);

 // Get PCollections out of a PCollectionTuple, using the same tags
 // that were used to put them in:
 PCollection<Integer> pcX = pcs.get(tag2);
 PCollection<String> pcY = pcs.get(tag1);
 PCollection<Iterable<String>> pcZ = pcs.get(tag3);

 // Get a map of all PCollections in a PCollectionTuple:
 Map<TupleTag<?>, PCollection<?>> allPcs = pcs.getAll();