com.google.cloud.dataflow.sdk.transforms

Class Combine.BinaryCombineDoubleFn

java.lang.Object

com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn<Double,double[],Double>

com.google.cloud.dataflow.sdk.transforms.Combine.BinaryCombineDoubleFn

All Implemented Interfaces:

com.google.cloud.dataflow.sdk.util.common.CounterProvider<Double>, Serializable

Direct Known Subclasses:

Sum.SumDoubleFn

Enclosing class:

Combine

public abstract static class Combine.BinaryCombineDoubleFn
extends Combine.CombineFn<Double,double[],Double>
implements com.google.cloud.dataflow.sdk.util.common.CounterProvider<Double>

An abstract subclass of Combine.CombineFn for implementing combiners that are more easily expressed as binary operations on doubles.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
BinaryCombineDoubleFn()

Method Summary

Modifier and Type	Method and Description
double[]	addInput(double[] accumulator, Double input) Adds the given input value to the given accumulator, returning the new accumulator value.
abstract double	apply(double left, double right) Applies the binary operation to the two operands, returning the result.
double[]	createAccumulator() Returns a new, mutable accumulator value, representing the accumulation of zero input values.
Double	extractOutput(double[] accumulator) Returns the output value that is the result of combining all the input values represented by the given accumulator.
Coder<double[]>	getAccumulatorCoder(CoderRegistry registry, Coder<Double> inputCoder) Returns the Coder to use for accumulator AccumT values, or null if it is not able to be inferred.
Coder<Double>	getDefaultOutputCoder(CoderRegistry registry, Coder<Double> inputCoder) Returns the Coder to use by default for output OutputT values, or null if it is not able to be inferred.
abstract double	identity() Returns the identity element of this operation, i.e.
double[]	mergeAccumulators(Iterable<double[]> accumulators) Returns an accumulator representing the accumulation of all the input values accumulated in the merging accumulators.

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

apply, asKeyedFn, getOutputType

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.google.cloud.dataflow.sdk.util.common.CounterProvider

getCounter

Constructor Detail

BinaryCombineDoubleFn

public BinaryCombineDoubleFn()

Method Detail

apply

public abstract double apply(double left,
                             double right)

Applies the binary operation to the two operands, returning the result.

identity

public abstract double identity()

Returns the identity element of this operation, i.e. an element e such that apply(e, x) == apply(x, e) == x for all values of x.

createAccumulator

public double[] 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<Double,double[],Double>

addInput

public double[] addInput(double[] accumulator,
                         Double input)

Description copied from class: Combine.CombineFn

Adds the given input value to the given accumulator, returning the new accumulator value.

For efficiency, the input accumulator may be modified and returned.

Specified by:

addInput in class Combine.CombineFn<Double,double[],Double>

mergeAccumulators

public double[] mergeAccumulators(Iterable<double[]> accumulators)

Description copied from class: Combine.CombineFn

Returns an accumulator representing the accumulation of all the input values accumulated in the merging accumulators.

May modify any of the argument accumulators. May return a fresh accumulator, or may return one of the (modified) argument accumulators.

Specified by:

mergeAccumulators in class Combine.CombineFn<Double,double[],Double>

extractOutput

public Double extractOutput(double[] accumulator)

Description copied from class: Combine.CombineFn

Returns the output value that is the result of combining all the input values represented by the given accumulator.

Specified by:

extractOutput in class Combine.CombineFn<Double,double[],Double>

getAccumulatorCoder

public Coder<double[]> getAccumulatorCoder(CoderRegistry registry,
                                           Coder<Double> 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<Double,double[],Double>

getDefaultOutputCoder

public Coder<Double> getDefaultOutputCoder(CoderRegistry registry,
                                           Coder<Double> inputCoder)

Description copied from class: Combine.CombineFn

Returns the Coder to use by default for output OutputT values, or null if it is not able to be inferred.

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

Overrides:

getDefaultOutputCoder in class Combine.CombineFn<Double,double[],Double>