Aggregate(TSource, TAccumulate, TResult) Method (ParallelQuery(TSource), TAccumulate, Func(TAccumulate, TSource, TAccumulate), Func(TAccumulate, TAccumulate, TAccumulate), Func(TAccumulate, TResult))

Task Parallel System.Threading

Applies in parallel an accumulator function over a sequence. This overload is not available in the sequential implementation.

Namespace:  System.Linq
Assembly:  System.Threading (in System.Threading.dll)

Syntax

Visual Basic (Declaration)
Public Shared Function Aggregate(Of TSource, TAccumulate, TResult) ( _
	source As ParallelQuery(Of TSource), _
	seed As TAccumulate, _
	updateAccumulatorFunc As Func(Of TAccumulate, TSource, TAccumulate), _
	combineAccumulatorsFunc As Func(Of TAccumulate, TAccumulate, TAccumulate), _
	resultSelector As Func(Of TAccumulate, TResult) _
) As TResult
C#
public static TResult Aggregate<TSource, TAccumulate, TResult>(
	ParallelQuery<TSource> source,
	TAccumulate seed,
	Func<TAccumulate, TSource, TAccumulate> updateAccumulatorFunc,
	Func<TAccumulate, TAccumulate, TAccumulate> combineAccumulatorsFunc,
	Func<TAccumulate, TResult> resultSelector
)

Parameters

source
Type: System.Linq..::.ParallelQuery<(Of <(TSource>)>)
A sequence to aggregate over.
seed
Type: TAccumulate
The initial accumulator value.
updateAccumulatorFunc
Type: System..::.Func<(Of <(TAccumulate, TSource, TAccumulate>)>)
An accumulator function to be invoked on each element in a partition.
combineAccumulatorsFunc
Type: System..::.Func<(Of <(TAccumulate, TAccumulate, TAccumulate>)>)
An accumulator function to be invoked on the yielded element from each partition.
resultSelector
Type: System..::.Func<(Of <(TAccumulate, TResult>)>)
A function to transform the final accumulator value into the result value.

Type Parameters

TSource
The type of the elements of source.
TAccumulate
The type of the accumulator value.
TResult
The type of the resulting value.

Return Value

The transformed final accumulator value.

Remarks

This overload is specific to processing a parallelized query. A parallelized query may partition the data source sequence into several sub-sequences (partitions). The updateAccumulatorFunc is invoked on each element within partitions. Each partition then yields a single accumulated result. The combineAccumulatorsFunc is then invoked on the results of each partition to yield a single element. This element is then transformed by the resultSelector function.

Exceptions

ExceptionCondition
System..::.ArgumentNullException source or updateAccumulatorFunc or combineAccumulatorsFunc or resultSelector is a null reference (Nothing in Visual Basic).
System..::.AggregateException One or more exceptions occurred during the evaluation of the query.
System..::.OperationCanceledException The query was canceled.

See Also