org.apache.beam.sdk.transforms

Class Count

java.lang.Object

org.apache.beam.sdk.transforms.Count

public class Count
extends Object

PTransorms to count the elements in a PCollection.

perElement() can be used to count the number of occurrences of each distinct element in the PCollection, perKey() can be used to count the number of values per key, and globally() can be used to count the total number of elements in a PCollection.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Count.PerElement<T> Count.PerElement<T> takes a PCollection<T> and returns a PCollection<KV<T, Long>> representing a map from each distinct element of the input PCollection to the number of times that element occurs in the input.

Method Summary

Modifier and Type	Method and Description
static <T> Combine.Globally<T,Long>	globally() Returns a Combine.Globally PTransform that counts the number of elements in its input PCollection.
static <T> Count.PerElement<T>	perElement() Returns a Count.PerElement PTransform that counts the number of occurrences of each element in its input PCollection.
static <K,V> Combine.PerKey<K,V,Long>	perKey() Returns a Combine.PerKey PTransform that counts the number of elements associated with each key of its input PCollection.

Methods inherited from class java.lang.Object

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

Method Detail

globally

public static <T> Combine.Globally<T,Long> globally()

Returns a Combine.Globally PTransform that counts the number of elements in its input PCollection.

perKey

public static <K,V> Combine.PerKey<K,V,Long> perKey()

Returns a Combine.PerKey PTransform that counts the number of elements associated with each key of its input PCollection.

perElement

public static <T> Count.PerElement<T> perElement()

Returns a Count.PerElement PTransform that counts the number of occurrences of each element in its input PCollection.

See Count.PerElement for more details.