Max (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 Max


  • public class Max
extends Object
    PTransforms for computing the maximum of the elements in a PCollection, or the maximum of the values associated with each key in a PCollection of KVs.

    Example 1: get the maximum of a PCollection of Doubles. 

     
 PCollection<Double> input = ...;
 PCollection<Double> max = input.apply(Max.doublesGlobally());

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

     
 PCollection<KV<String, Integer>> input = ...;
 PCollection<KV<String, Integer>> maxPerKey = input
     .apply(Max.<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 maximum of the input PCollection's elements, or Integer.MIN_VALUE 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 maximum of the values associated with that key in the input PCollection.

        See Combine.PerKey for how this affects timestamps and windowing.

      • 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 maximum of the input PCollection's elements, or Long.MIN_VALUE 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 maximum of the values associated with that key in the input PCollection.

        See Combine.PerKey for how this affects timestamps and windowing.

      • 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 maximum of the input PCollection's elements, or Double.NEGATIVE_INFINITY 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 maximum of the values associated with that key in the input PCollection.

        See Combine.PerKey for how this affects timestamps and windowing.

      • globally

        public static <T extends Comparable<? super T>> Combine.Globally<T,T> globally()
        Returns a PTransform that takes an input PCollection<T> and returns a PCollection<T> whose contents is the maximum according to the natural ordering of T of the input PCollection's elements, or null if there are no elements.

      • perKey

        public static <K,T extends Comparable<? super T>> Combine.PerKey<K,T,T> perKey()
        Returns a PTransform that takes an input PCollection<KV<K, T>> and returns a PCollection<KV<K, T>> that contains an output element mapping each distinct key in the input PCollection to the maximum according to the natural ordering of T of the values associated with that key in the input PCollection.

        See Combine.PerKey for how this affects timestamps and windowing.

      • globally

        public static <T,ComparatorT extends Comparator<? super T> & Serializable> Combine.Globally<T,T> globally(ComparatorT comparator)
        Returns a PTransform that takes an input PCollection<T> and returns a PCollection<T> whose contents is the maximum of the input PCollection's elements, or null if there are no elements.

      • perKey

        public static <K,T,ComparatorT extends Comparator<? super T> & Serializable> Combine.PerKey<K,T,T> perKey(ComparatorT comparator)
        Returns a PTransform that takes an input PCollection<KV<K, T>> and returns a PCollection<KV<K, T>> that contains one output element per key mapping each to the maximum of the values associated with that key in the input PCollection.

        See Combine.PerKey for how this affects timestamps and windowing.