Seq.windowed<'T> Function (F#)

Returns a sequence that yields sliding windows of containing elements drawn from the input sequence. Each window is returned as a fresh array.

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

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

// Signature:
Seq.windowed : int -> seq<'T> -> seq<'T []>

// Usage:
Seq.windowed windowSize source

Parameters

• windowSize
  Type: int

  The number of elements in each window.

• source
  Type: seq<'T>

  The input sequence.

Exceptions

Return Value

The result sequence.

Remarks

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

Example

The following example demonstrates the use of Seq.windowed as part of a computation of a moving average for a sequence of numbers.

let seqNumbers = [ 1.0; 1.5; 2.0; 1.5; 1.0; 1.5 ] :> seq<float>
let seqWindows = Seq.windowed 3 seqNumbers
let seqMovingAverage = Seq.map Array.average seqWindows
printfn "Initial sequence: "
printSeq seqNumbers
printfn "\nWindows of length 3: "
printSeq seqWindows
printfn "\nMoving average: "
printSeq seqMovingAverage

Initial sequence: 
1.0 1.5 2.0 1.5 1.0 1.5 

Windows of length 3: 
[|1.0; 1.5; 2.0|] [|1.5; 2.0; 1.5|] [|2.0; 1.5; 1.0|] [|1.5; 1.0; 1.5|] 

Moving average: 
1.5 1.666666667 1.5 1.333333333 

Platforms

Windows 8, Windows 7, Windows Server 2012, Windows Server 2008 R2

Version Information

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

See Also

Reference

Collections.Seq Module (F#)

Microsoft.FSharp.Collections Namespace (F#)