PCollectionList (Apache Beam SDK 0.2.0-incubating API)

java.lang.Object
- org.apache.beam.sdk.values.PCollectionList<T>

Type Parameters:: T - the type of the elements of all the PCollections in this list

All Implemented Interfaces:: PInput, POutput

public class PCollectionList<T>
extends Object
implements PInput, POutput

A PCollectionList<T> is an immutable list of homogeneously typed PCollection<T>s. A PCollectionList is used, for instance, as the input to Flatten or the output of Partition.

PCollectionLists can be created and accessed like follows:

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

 // Create a PCollectionList with three PCollections:
 PCollectionList<String> pcs = PCollectionList.of(pc1).and(pc2).and(pc3);

 // Create an empty PCollectionList:
 Pipeline p = ...;
 PCollectionList<String> pcs2 = PCollectionList.<String>empty(p);

 // Get PCollections out of a PCollectionList, by index (origin 0):
 PCollection<String> pcX = pcs.get(1);
 PCollection<String> pcY = pcs.get(0);
 PCollection<String> pcZ = pcs.get(2);

 // Get a list of all PCollections in a PCollectionList:
 List<PCollection<String>> allPcs = pcs.getAll();

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`PCollectionList<T>`	`and(Iterable<PCollection<T>> pcs)` Returns a new `PCollectionList` that has all the `PCollections` of this `PCollectionList` plus the given `PCollections` appended to the end, in order.
`PCollectionList<T>`	`and(PCollection<T> pc)` Returns a new `PCollectionList` that has all the `PCollections` of this `PCollectionList` plus the given `PCollection` appended to the end.
`<OutputT extends POutput> OutputT`	`apply(PTransform<PCollectionList<T>,OutputT> t)` Like `apply(String, PTransform)` but defaulting to the name of the `PTransform`.
`<OutputT extends POutput> OutputT`	`apply(String name, PTransform<PCollectionList<T>,OutputT> t)` Applies the given `PTransform` to this input `PCollectionList`, using `name` to identify this specific application of the transform.
`static <T> PCollectionList<T>`	`empty(Pipeline pipeline)` Returns an empty `PCollectionList` that is part of the given `Pipeline`.
`Collection<? extends PValue>`	`expand()` Expands this `PInput` into a list of its component output `PValues`.
`void`	`finishSpecifying()` After building, finalizes this `PInput` to make it ready for being used as an input to a `PTransform`.
`void`	`finishSpecifyingOutput()` As part of applying the producing `PTransform`, finalizes this output to make it ready for being used as an input and for running.
`PCollection<T>`	`get(int index)` Returns the `PCollection` at the given index (origin zero).
`List<PCollection<T>>`	`getAll()` Returns an immutable List of all the `PCollections` in this `PCollectionList`.
`Pipeline`	`getPipeline()` Returns the owning `Pipeline` of this `PInput`.
`static <T> PCollectionList<T>`	`of(Iterable<PCollection<T>> pcs)` Returns a `PCollectionList` containing the given `PCollections`, in order.
`static <T> PCollectionList<T>`	`of(PCollection<T> pc)` Returns a singleton `PCollectionList` containing the given `PCollection`.
`void`	`recordAsOutput(AppliedPTransform<?,?,?> transform)` Records that this `POutput` is an output of the given `PTransform`.
`int`	`size()` Returns the number of `PCollections` in this `PCollectionList`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - empty
```
public static <T> PCollectionList<T> empty(Pipeline pipeline)
```
    Returns an empty PCollectionList that is part of the given Pipeline.
    Longer PCollectionLists can be created by calling and(org.apache.beam.sdk.values.PCollection<T>) on the result.
  - of
```
public static <T> PCollectionList<T> of(PCollection<T> pc)
```
    Returns a singleton PCollectionList containing the given PCollection.
    Longer PCollectionLists can be created by calling and(org.apache.beam.sdk.values.PCollection<T>) on the result.
  - of
```
public static <T> PCollectionList<T> of(Iterable<PCollection<T>> pcs)
```
    Returns a PCollectionList containing the given PCollections, in order.
    The argument list cannot be empty.
    All the PCollections in the resulting PCollectionList must be part of the same Pipeline.
    Longer PCollectionLists can be created by calling and(org.apache.beam.sdk.values.PCollection<T>) on the result.
  - and
```
public PCollectionList<T> and(PCollection<T> pc)
```
    Returns a new PCollectionList that has all the PCollections of this PCollectionList plus the given PCollection appended to the end.
    All the PCollections in the resulting PCollectionList must be part of the same Pipeline.
  - and
```
public PCollectionList<T> and(Iterable<PCollection<T>> pcs)
```
    Returns a new PCollectionList that has all the PCollections of this PCollectionList plus the given PCollections appended to the end, in order.
    All the PCollections in the resulting PCollectionList must be part of the same Pipeline.
  - size
```
public int size()
```
    Returns the number of PCollections in this PCollectionList.
  - get
```
public PCollection<T> get(int index)
```
    Returns the PCollection at the given index (origin zero).
    
    Throws:
    
    IndexOutOfBoundsException - if the index is out of the range [0..size()-1].
  - getAll
```
public List<PCollection<T>> getAll()
```
    Returns an immutable List of all the PCollections in this PCollectionList.
  - apply
```
public <OutputT extends POutput> OutputT apply(PTransform<PCollectionList<T>,OutputT> t)
```
    Like apply(String, PTransform) but defaulting to the name of the PTransform.
  - apply
```
public <OutputT extends POutput> OutputT apply(String name,
                                               PTransform<PCollectionList<T>,OutputT> t)
```
    Applies the given PTransform to this input PCollectionList, using name to identify this specific application of the transform. This name is used in various places, including the monitoring UI, logging, and to stably identify this application node in the job graph.
    
    Returns:
    
    the output of the applied PTransform
  - getPipeline
```
public Pipeline getPipeline()
```
    Description copied from interface: PInput
    
    Returns the owning Pipeline of this PInput.
    
    Specified by:
    
    getPipeline in interface PInput
    
    Specified by:
    
    getPipeline in interface POutput
  - expand
```
public Collection<? extends PValue> expand()
```
    Description copied from interface: PInput
    Expands this PInput into a list of its component output PValues.
    - A PValue expands to itself.
    - A tuple or list of PValues (such as PCollectionTuple or PCollectionList) expands to its component PValue PValues.
    Not intended to be invoked directly by user code.
    Specified by:
    
    expand in interface PInput
    
    Specified by:
    
    expand in interface POutput
  - recordAsOutput
```
public void recordAsOutput(AppliedPTransform<?,?,?> transform)
```
    Description copied from interface: POutput
    
    Records that this POutput is an output of the given PTransform.
    For a compound POutput, it is advised to call this method on each component POutput.
    This is not intended to be invoked by user code, but is automatically invoked as part of applying the producing PTransform.
    
    Specified by:
    
    recordAsOutput in interface POutput
  - finishSpecifying
```
public void finishSpecifying()
```
    Description copied from interface: PInput
    
    After building, finalizes this PInput to make it ready for being used as an input to a PTransform.
    Automatically invoked whenever apply() is invoked on this PInput, so users do not normally call this explicitly.
    
    Specified by:
    
    finishSpecifying in interface PInput
  - finishSpecifyingOutput
```
public void finishSpecifyingOutput()
```
    Description copied from interface: POutput
    
    As part of applying the producing PTransform, finalizes this output to make it ready for being used as an input and for running.
    This includes ensuring that all PCollections have Coders specified or defaulted.
    Automatically invoked whenever this POutput is used as a PInput to another PTransform, or if never used as a PInput, when Pipeline.run() is called, so users do not normally call this explicitly.
    
    Specified by:
    
    finishSpecifyingOutput in interface POutput

Class PCollectionList<T>

Method Summary

Methods inherited from class java.lang.Object

Method Detail

empty

of

of

and

and

size

get

getAll

apply

apply

getPipeline

expand

recordAsOutput

finishSpecifying

finishSpecifyingOutput