org.apache.giraph.aggregators

Interface Aggregator<A extends org.apache.hadoop.io.Writable>

Type Parameters:

A - Aggregated value

All Known Implementing Classes:

BasicAggregator, BooleanAndAggregator, BooleanOrAggregator, BooleanOverwriteAggregator, DoubleDenseVectorSumAggregator, DoubleMaxAggregator, DoubleMinAggregator, DoubleOverwriteAggregator, DoubleProductAggregator, DoubleSparseVectorSumAggregator, DoubleSumAggregator, FloatDenseVectorSumAggregator, FloatMaxAggregator, FloatMinAggregator, FloatOverwriteAggregator, FloatProductAggregator, FloatSparseVectorSumAggregator, FloatSumAggregator, IntDenseVectorSumAggregator, IntMaxAggregator, IntMinAggregator, IntOverwriteAggregator, IntProductAggregator, IntSparseVectorSumAggregator, IntSumAggregator, LongDenseVectorSumAggregator, LongMaxAggregator, LongMinAggregator, LongOverwriteAggregator, LongProductAggregator, LongSparseVectorSumAggregator, LongSumAggregator, PageRankWithKryoSimpleWritable.DoubleMaxWrapperAggregator, PageRankWithKryoSimpleWritable.DoubleMinWrapperAggregator, TextAppendAggregator

public interface Aggregator<A extends org.apache.hadoop.io.Writable>

Interface for Aggregator. Allows aggregate operations for all vertices in a given superstep.

Method Summary

Modifier and Type	Method and Description
void	aggregate(A value) Add a new value.
A	createInitialValue() Return new aggregated value which is neutral to aggregate operation.
A	getAggregatedValue() Return current aggregated value.
void	reset() Reset the value of aggregator to neutral value
void	setAggregatedValue(A value) Set aggregated value.

Method Detail

aggregate

void aggregate(A value)

Add a new value. Needs to be commutative and associative

Parameters:

value - Value to be aggregated.

createInitialValue

A createInitialValue()

Return new aggregated value which is neutral to aggregate operation. Must be changeable without affecting internals of Aggregator

Returns:

Neutral value

getAggregatedValue

A getAggregatedValue()

Return current aggregated value. Needs to be initialized if aggregate or setAggregatedValue have not been called before.

Returns:

Aggregated

setAggregatedValue

void setAggregatedValue(A value)

Set aggregated value. Can be used for initialization or reset.

Parameters:

value - Value to be set.

reset

void reset()

Reset the value of aggregator to neutral value