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Enumerable.Average Method (IEnumerable<Nullable<Double>>)

Computes the average of a sequence of nullable Double values.

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

public static Nullable<double> Average(
	this IEnumerable<Nullable<double>> source
)

Parameters

source
Type: System.Collections.Generic.IEnumerable<Nullable<Double>>
A sequence of nullable Double values to calculate the average of.

Return Value

Type: System.Nullable<Double>
The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<Nullable<Double>>. 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
ArgumentNullException

source is null.

If the sum of the elements is too large to represent as a Double, this method returns positive or negative infinity.

In Visual Basic query expression syntax, an Aggregate Into Average() clause translates to an invocation of Average.

The following code example demonstrates how to use Average(IEnumerable<Nullable<Int64>>) to calculate an average.

NoteNote

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, substitute the elements of the source sequence with elements of the appropriate numerical type.


            long?[] longs = { null, 10007L, 37L, 399846234235L };

            double? average = longs.Average();

            Console.WriteLine("The average is {0}.", average);

            // This code produces the following output:
            //
            // The average is 133282081426.333. 



.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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