com.google.cloud.dataflow.sdk.transforms

Class Mean.MeanFn<NumT extends Number>

java.lang.Object

com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn<InputT,AccumT,OutputT>

com.google.cloud.dataflow.sdk.transforms.Combine.AccumulatingCombineFn<NumT,com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum,Double>

com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn<NumT>

Type Parameters:

NumT - the type of the Numbers being combined

All Implemented Interfaces:

Serializable

Enclosing class:

Mean

public static class Mean.MeanFn<NumT extends Number>
extends Combine.AccumulatingCombineFn<NumT,com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum,Double>

A Combine.CombineFn that computes the arithmetic mean (a.k.a. average) of an Iterable of numbers of type N, useful as an argument to Combine.globally(com.google.cloud.dataflow.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>) or Combine.perKey(com.google.cloud.dataflow.sdk.transforms.SerializableFunction<java.lang.Iterable<V>, V>).

Returns Double.NaN if combining zero elements.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.transforms.Combine.AccumulatingCombineFn

Combine.AccumulatingCombineFn.Accumulator<InputT,AccumT,OutputT>

Constructor Summary

Constructors

Constructor and Description
Mean.MeanFn() Constructs a combining function that computes the mean over a collection of values of type N.

Method Summary

Methods

Modifier and Type	Method and Description
com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum	createAccumulator() Returns a new, mutable accumulator value, representing the accumulation of zero input values.
Coder<com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum>	getAccumulatorCoder(CoderRegistry registry, Coder<NumT> inputCoder) Returns the Coder to use for accumulator AccumT values, or null if it is not able to be inferred.

Methods inherited from class com.google.cloud.dataflow.sdk.transforms.Combine.AccumulatingCombineFn

addInput, extractOutput, mergeAccumulators

Methods inherited from class com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn

apply, asKeyedFn, getDefaultOutputCoder, getOutputType

Methods inherited from class java.lang.Object

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

Constructor Detail

Mean.MeanFn

public Mean.MeanFn()

Constructs a combining function that computes the mean over a collection of values of type N.

Method Detail

createAccumulator

public com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum createAccumulator()

Description copied from class: Combine.CombineFn

Returns a new, mutable accumulator value, representing the accumulation of zero input values.

Specified by:

createAccumulator in class Combine.CombineFn<NumT extends Number,com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum,Double>

getAccumulatorCoder

public Coder<com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum> getAccumulatorCoder(CoderRegistry registry,
                                                                                       Coder<NumT> inputCoder)

Description copied from class: Combine.CombineFn

Returns the Coder to use for accumulator AccumT values, or null if it is not able to be inferred.

By default, uses the knowledge of the Coder being used for InputT values and the enclosing Pipeline's CoderRegistry to try to infer the Coder for AccumT values.

This is the Coder used to send data through a communication-intensive shuffle step, so a compact and efficient representation may have significant performance benefits.

Overrides:

getAccumulatorCoder in class Combine.CombineFn<NumT extends Number,com.google.cloud.dataflow.sdk.transforms.Mean.MeanFn.CountSum,Double>