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ParallelEnumerable::Average<TSource> Method (ParallelQuery<TSource>, Func<TSource, Nullable<Int32>>)

Computes in parallel the average of a sequence of values that are obtained by invoking a transform function on each element of the input sequence.

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

generic<typename TSource>
static Nullable<double> Average(
	ParallelQuery<TSource>^ source, 
	Func<TSource, Nullable<int>>^ selector

Type Parameters


The type of elements of source.


Type: System.Linq::ParallelQuery<TSource>

A sequence of values that are used to calculate an average.

Type: System::Func<TSource, Nullable<Int32>>

A transform function to apply to each element.

Return Value

Type: System::Nullable<Double>
The average of the sequence of values.

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).


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


source or selector is a null reference (Nothing in Visual Basic).


The sum or count of the elements in the sequence is larger than MaxValue. -or- One or more exceptions occurred during the evaluation of the query.


source contains no elements.


(Thrown as inner exception in an AggregateException). The selector function returns a value greater than MaxValue for the element type.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1
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