Enumerable.Average(Of TSource) Method (IEnumerable(Of TSource), Func(Of TSource, Nullable(Of Int32)))
Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.
Assembly: System.Core (in System.Core.dll)
<ExtensionAttribute> Public Shared Function Average(Of TSource) ( source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Integer)) ) As Nullable(Of Double)
Parameters
- source
-
Type:
System.Collections.Generic.IEnumerable(Of TSource)
A sequence of values to calculate the average of.
- selector
-
Type:
System.Func(Of TSource, Nullable(Of Int32))
A transform function to apply to each element.
Return Value
Type: System.Nullable(Of Double)The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.
Type Parameters
- TSource
The type of the elements of source.
| Exception | Condition |
|---|---|
| ArgumentNullException | source or selector is null. |
| 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.
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, 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
Available since 8
.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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