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ParallelEnumerable.Aggregate<TSource, TAccumulate, TResult> Method (ParallelQuery<TSource>, Func<TAccumulate>, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, TAccumulate, TAccumulate>, Func<TAccumulate, TResult>)

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

Namespace:  System.Linq
Assemblies:   System.Linq.Parallel (in System.Linq.Parallel.dll)
  System.Core (in System.Core.dll)

public static TResult Aggregate<TSource, TAccumulate, TResult>(
	this ParallelQuery<TSource> source,
	Func<TAccumulate> seedFactory,
	Func<TAccumulate, TSource, TAccumulate> updateAccumulatorFunc,
	Func<TAccumulate, TAccumulate, TAccumulate> combineAccumulatorsFunc,
	Func<TAccumulate, TResult> resultSelector
)

Type Parameters

TSource

The type of the elements of source.

TAccumulate

The type of the accumulator value.

TResult

The type of the resulting value.

Parameters

source
Type: System.Linq.ParallelQuery<TSource>

A sequence to aggregate over.

seedFactory
Type: System.Func<TAccumulate>

A function that returns the initial accumulator value.

updateAccumulatorFunc
Type: System.Func<TAccumulate, TSource, TAccumulate>

An accumulator function to be invoked on each element in a partition.

combineAccumulatorsFunc
Type: System.Func<TAccumulate, TAccumulate, TAccumulate>

An accumulator function to be invoked on the yielded accumulator result from each partition.

resultSelector
Type: System.Func<TAccumulate, TResult>

A function to transform the final accumulator value into the result value.

Return Value

Type: TResult
The transformed final accumulator value.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type ParallelQuery<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
OperationCanceledException

The query was canceled with the token passed in through WithCancellation.

ArgumentNullException

source or seedFactory or updateAccumulatorFunc or combineAccumulatorsFunc or resultSelector is a null reference (Nothing in Visual Basic).

AggregateException

One or more exceptions occurred during the evaluation of the query.

InvalidOperationException

source contains no elements.

This overload is specific to parallelized queries. 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.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Windows Phone 8.1, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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