Package org.apache.beam.sdk.transforms

Class Mean

java.lang.Object
org.apache.beam.sdk.transforms.Mean
public class Mean extends Object
PTransforms for computing the arithmetic mean (a.k.a. average) of the elements in a PCollection, or the mean of the values associated with each key in a PCollection of KVs.

Example 1: get the mean of a PCollection of Longs. 


 PCollection<Long> input = ...;
 PCollection<Double> mean = input.apply(Mean.<Long>globally());

Example 2: calculate the mean of the Integers associated with each unique key (which is of type String). 


 PCollection<KV<String, Integer>> input = ...;
 PCollection<KV<String, Double>> meanPerKey =
     input.apply(Mean.<String, Integer>perKey());

  • Method Summary

    Modifier and Type
    Method
    Description
    static <NumT extends Number>
    Combine.Globally<NumT,Double>
    globally()
    Returns a PTransform that takes an input PCollection<NumT> and returns a PCollection<Double> whose contents is the mean of the input PCollection's elements, or 0 if there are no elements.
    static <NumT extends Number>
    Combine.AccumulatingCombineFn<NumT,org.apache.beam.sdk.transforms.Mean.CountSum<NumT>,Double>
    of()
    A Combine.CombineFn that computes the arithmetic mean (a.k.a.
    static <K, NumT extends Number>
    Combine.PerKey<K,NumT,Double>
    perKey()
    Returns a PTransform that takes an input PCollection<KV<K, N>> and returns a PCollection<KV<K, Double>> that contains an output element mapping each distinct key in the input PCollection to the mean of the values associated with that key in the input PCollection.

    Methods inherited from class java.lang.Object

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