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# Enumerable.Average Method (IEnumerable(Of Double))

.NET Framework 4.5

Computes the average of a sequence of Double values.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)
```'Declaration
<ExtensionAttribute> _
Public Shared Function Average ( _
source As IEnumerable(Of Double) _
) As Double
```

#### Parameters

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

A sequence of Double values to calculate the average of.

#### Return Value

Type: System.Double
The average of the sequence of values.

#### Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of 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 Nothing.

InvalidOperationException

source contains no elements.

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(Of Int32)) to calculate an average.

Note

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.

```        ' Create a list of integers.
Dim grades As New List(Of Integer)(New Integer() {78, 92, 100, 37, 81})

' Determine the average value in the list.
Dim avg As Double = grades.Average()

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

' This code produces the following output:
'
' The average grade is 77.6
```

#### .NET Framework

Supported in: 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

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.