Package org.apache.beam.sdk.transforms

Class Sum

java.lang.Object

org.apache.beam.sdk.transforms.Sum

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());
 

Method Summary

Modifier and Type	Method	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.
static Combine.BinaryCombineDoubleFn	ofDoubles()	A SerializableFunction that computes the sum of an Iterable of Doubles, useful as an argument to Combine.globally(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>) or Combine.perKey(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>).
static Combine.BinaryCombineIntegerFn	ofIntegers()	A SerializableFunction that computes the sum of an Iterable of Integers, useful as an argument to Combine.globally(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>) or Combine.perKey(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>).
static Combine.BinaryCombineLongFn	ofLongs()	A SerializableFunction that computes the sum of an Iterable of Longs, useful as an argument to Combine.globally(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>) or Combine.perKey(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

integersGlobally

public 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.

integersPerKey

public 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.

longsGlobally

public 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.

longsPerKey

public 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.

doublesGlobally

public 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.

doublesPerKey

public 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.

ofIntegers

public static Combine.BinaryCombineIntegerFn ofIntegers()

A SerializableFunction that computes the sum of an Iterable of Integers, useful as an argument to Combine.globally(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>) or Combine.perKey(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>).

ofDoubles

public static Combine.BinaryCombineDoubleFn ofDoubles()

A SerializableFunction that computes the sum of an Iterable of Doubles, useful as an argument to Combine.globally(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>) or Combine.perKey(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>).

ofLongs

public static Combine.BinaryCombineLongFn ofLongs()

A SerializableFunction that computes the sum of an Iterable of Longs, useful as an argument to Combine.globally(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>) or Combine.perKey(org.apache.beam.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>).