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EnumerableAverage Method

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Computes the average of a sequence of Int32 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)

public static double Average<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, int> selector
generic<typename TSource>
static double Average(
	IEnumerable<TSource>^ source,
	Func<TSource, int>^ selector
static member Average<'TSource> : 
        source:IEnumerable<'TSource> *
        selector:Func<'TSource, int> -> float
Public Shared Function Average(Of TSource) (
	source As IEnumerable(Of TSource),
	selector As Func(Of TSource, Integer)
) As Double



A sequence of values to calculate the average of.


A transform function to apply to each element.

Return Value


The average of the sequence of values.

Type Parameters


The type of the elements of source.

Exception Condition

source or selector is null.


source contains no elements.


The sum of the elements in the sequence is larger than MaxValue.

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 to calculate an average.

string[] fruits = { "apple", "banana", "mango", "orange", "passionfruit", "grape" };

double average = fruits.Average(s => s.Length);

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

// This code produces the following output:
// The average string length is 6.5. 
' Create an array of strings.
Dim fruits() As String =
{"apple", "banana", "mango", "orange", "passionfruit", "grape"}

' Determine the average length of the strings in the array.
Dim avg As Double = fruits.Average(Function(s) s.Length)

' Display the output.
MsgBox("The average string length is " & avg)

' This code produces the following output:
' The average string length is 6.5
Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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