Enumerable.Average(Of TSource) Method (IEnumerable(Of TSource), Func(Of TSource, Int32))
Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.
Assembly: System.Core (in System.Core.dll)
'Declaration <ExtensionAttribute> _ Public Shared Function Average(Of TSource) ( _ source As IEnumerable(Of TSource), _ selector As Func(Of TSource, Integer) _ ) As Double
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Collections.Generic.IEnumerable(Of TSource)
A sequence of values to calculate the average of.
- selector
- Type: System.Func(Of TSource, Int32)
A transform function to apply to each element.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of 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).| Exception | Condition |
|---|---|
| ArgumentNullException | source or selector is Nothing. |
| InvalidOperationException | source contains no elements. |
| OverflowException | 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(Of TSource)(IEnumerable(Of TSource), Func(Of TSource, Int32)) to calculate an average.
' 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
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.