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Enumerable.Average(Of TSource) Method (IEnumerable(Of TSource), Func(Of TSource, Single))

 

Computes the average of a sequence of Single 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)

<ExtensionAttribute>
Public Shared Function Average(Of TSource) (
	source As IEnumerable(Of TSource),
	selector As Func(Of TSource, Single)
) As Single

Parameters

source
Type: System.Collections.Generic.IEnumerable(Of TSource)

A sequence of values to calculate the average of.

selector
Type: System.Func(Of TSource, Single)

A transform function to apply to each element.

Return Value

Type: System.Single

The average of the sequence of values.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
ArgumentNullException

source or selector is null.

InvalidOperationException

source contains no elements.

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(Of TSource)(IEnumerable(Of TSource), Func(Of TSource, Int32)) to calculate an average.

System_CAPS_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, change the body of the selector function.

' 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 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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