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Queryable.Average Method (IQueryable<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 IQueryable<Nullable<double>> source
)

Parameters

source
Type: System.Linq.IQueryable<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 null values.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<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.

The Average(IQueryable<Nullable<Double>>) method generates a MethodCallExpression that represents calling Average(IQueryable<Nullable<Double>>) itself. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Average(IQueryable<Nullable<Double>>) depends on the implementation of the type of the source parameter. The expected behavior is that it calculates the average of the values in source.

The following code example demonstrates how to use Average(IQueryable<Nullable<Int64>>) to calculate the average of a sequence of values.

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.AsQueryable().Average();

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

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

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, 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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