List.averageBy<'T,^U> Function (F#)

  • Article

Returns the average of the elements generated by applying the function to each element of the list.

Namespace/Module Path: Microsoft.FSharp.Collections.List

Assembly: FSharp.Core (in FSharp.Core.dll)

// Signature:
List.averageBy : ('T -> ^U) -> 'T list -> ^U (requires ^U with static member (+) and ^U with static member DivideByInt and ^U with static member Zero)

// Usage:
List.averageBy projection list

Parameters

  • projection
    Type: 'T -> ^U

    The function to transform the list elements into the type to be averaged.

  • list
    Type: 'T list

    The input list.

Exceptions

Exception

Condition

ArgumentException

Thrown when the list is empty.

Return Value

The resulting average.

Remarks

This function is named AverageBy in compiled assemblies. If you are accessing the member from a language other than F#, or through reflection, use this name.

Example

The following code example illustrates the use of List.averageBy.

let avg2 = List.averageBy (fun elem -> float elem) [1 .. 10]
printfn "%f" avg2

Output

5.500000

Platforms

Windows 7, Windows Vista SP2, Windows XP SP3, Windows XP x64 SP2, Windows Server 2008 R2, Windows Server 2008 SP2, Windows Server 2003 SP2

Version Information

F# Runtime

Supported in: 2.0, 4.0

Silverlight

Supported in: 3

See Also

Reference

Collections.List Module (F#)

Microsoft.FSharp.Collections Namespace (F#)