public class Sum extends Object
PTransforms for computing the sum of the elements in a
PCollection, or the sum of the values associated with
each key in a PCollection of KVs.
Example 1: get the sum of a PCollection of Doubles.
PCollection<Double> input = ...;
PCollection<Double> sum = input.apply(Sum.doublesGlobally());
Example 2: calculate the sum of the Integers
associated with each unique key (which is of type String).
PCollection<KV<String, Integer>> input = ...;
PCollection<KV<String, Integer>> sumPerKey = input
.apply(Sum.<String>integersPerKey());
| Modifier and Type | Method and Description |
|---|---|
static Combine.Globally<Double,Double> |
doublesGlobally()
Returns a
PTransform that takes an input
PCollection<Double> and returns a
PCollection<Double> whose contents is the sum of the
input PCollection's elements, or
0 if there are no elements. |
static <K> Combine.PerKey<K,Double,Double> |
doublesPerKey()
Returns a
PTransform that takes an input
PCollection<KV<K, Double>> and returns a
PCollection<KV<K, Double>> that contains an output
element mapping each distinct key in the input
PCollection to the sum of the values associated with
that key in the input PCollection. |
static Combine.Globally<Integer,Integer> |
integersGlobally()
Returns a
PTransform that takes an input
PCollection<Integer> and returns a
PCollection<Integer> whose contents is the sum of the
input PCollection's elements, or
0 if there are no elements. |
static <K> Combine.PerKey<K,Integer,Integer> |
integersPerKey()
Returns a
PTransform that takes an input
PCollection<KV<K, Integer>> and returns a
PCollection<KV<K, Integer>> that contains an output
element mapping each distinct key in the input
PCollection to the sum of the values associated with
that key in the input PCollection. |
static Combine.Globally<Long,Long> |
longsGlobally()
Returns a
PTransform that takes an input
PCollection<Long> and returns a
PCollection<Long> whose contents is the sum of the
input PCollection's elements, or
0 if there are no elements. |
static <K> Combine.PerKey<K,Long,Long> |
longsPerKey()
Returns a
PTransform that takes an input
PCollection<KV<K, Long>> and returns a
PCollection<KV<K, Long>> that contains an output
element mapping each distinct key in the input
PCollection to the sum of the values associated with
that key in the input PCollection. |
public static Combine.Globally<Integer,Integer> integersGlobally()
PTransform that takes an input
PCollection<Integer> and returns a
PCollection<Integer> whose contents is the sum of the
input PCollection's elements, or
0 if there are no elements.public static <K> Combine.PerKey<K,Integer,Integer> integersPerKey()
PTransform that takes an input
PCollection<KV<K, Integer>> and returns a
PCollection<KV<K, Integer>> that contains an output
element mapping each distinct key in the input
PCollection to the sum of the values associated with
that key in the input PCollection.public static Combine.Globally<Long,Long> longsGlobally()
PTransform that takes an input
PCollection<Long> and returns a
PCollection<Long> whose contents is the sum of the
input PCollection's elements, or
0 if there are no elements.public static <K> Combine.PerKey<K,Long,Long> longsPerKey()
PTransform that takes an input
PCollection<KV<K, Long>> and returns a
PCollection<KV<K, Long>> that contains an output
element mapping each distinct key in the input
PCollection to the sum of the values associated with
that key in the input PCollection.public static Combine.Globally<Double,Double> doublesGlobally()
PTransform that takes an input
PCollection<Double> and returns a
PCollection<Double> whose contents is the sum of the
input PCollection's elements, or
0 if there are no elements.public static <K> Combine.PerKey<K,Double,Double> doublesPerKey()
PTransform that takes an input
PCollection<KV<K, Double>> and returns a
PCollection<KV<K, Double>> that contains an output
element mapping each distinct key in the input
PCollection to the sum of the values associated with
that key in the input PCollection.