Sum (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

com.google.cloud.dataflow.sdk.transforms

Class 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 Detail

      • 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.


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