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Visual Studio 2012
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F# Core Library Reference
Microsoft.FSharp.Collections Namespace
Array Module
Array.Parallel Module
Array.append<'T> Function
Array.average<^T> Function
Array.averageBy<'T,^U> Function
Array.blit<'T> Function
Array.choose<'T,'U> Function
Array.collect<'T,'U> Function
Array.concat<'T> Function
Array.copy<'T> Function
Array.create<'T> Function
Array.empty<'T> Type Function
Array.exists<'T> Function
Array.exists2<'T1,'T2> Function
Array.fill<'T> Function
Array.filter<'T> Function
Array.find<'T> Function
Array.findIndex<'T> Function
Array.fold<'T,'State> Function
Array.fold2<'T1,'T2,'State> Function
Array.foldBack<'T,'State> Function
Array.foldBack2<'T1,'T2,'State> Function
Array.forall<'T> Function
Array.forall2<'T1,'T2> Function
Array.get<'T> Function
Array.init<'T> Function
Array.isEmpty<'T> Function
Array.iter<'T> Function
Array.iter2<'T1,'T2> Function
Array.iteri<'T> Function
Array.iteri2<'T1,'T2> Function
Array.length<'T> Function
Array.map<'T,'U> Function
Array.map2<'T1,'T2,'U> Function
Array.mapi<'T,'U> Function
Array.mapi2<'T1,'T2,'U> Function
Array.max<'T> Function
Array.maxBy<'T,'U> Function
Array.min<'T> Function
Array.minBy<'T,'U> Function
Array.ofList<'T> Function
Array.ofSeq<'T> Function
Array.partition<'T> Function
Array.permute<'T> Function
Array.pick<'T,'U> Function
Array.reduce<'T> Function
Array.reduceBack<'T> Function
Array.rev<'T> Function
Array.scan<'T,'State> Function
Array.scanBack<'T,'State> Function
Array.set<'T> Function
Array.sort<'T> Function
Array.sortBy<'T,'Key> Function
Array.sortInPlace<'T> Function
Array.sortInPlaceBy<'T,'Key> Function
Array.sortInPlaceWith<'T> Function
Array.sortWith<'T> Function
Array.sub<'T> Function
Array.sum<^T> Function
Array.sumBy<'T,^U> Function
Array.toList<'T> Function
Array.toSeq<'T> Function
Array.tryFind<'T> Function
Array.tryFindIndex<'T> Function
Array.tryPick<'T,'U> Function
Array.unzip<'T1,'T2> Function
Array.unzip3<'T1,'T2,'T3> Function
Array.zeroCreate<'T> Function
Array.zip<'T1,'T2> Function
Array.zip3<'T1,'T2,'T3> Function
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Array.mapi<'T,'U> Function (F#)

Visual Studio 2012

Builds a new array whose elements are the results of applying the given function to each of the elements of the array. The integer index passed to the function indicates the index of element being transformed.

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

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

Copy 
// Signature:
Array.mapi : (int -> 'T -> 'U) -> 'T [] -> 'U []

// Usage:
Array.mapi mapping array
mapping

Type: int -> 'T -> 'U

The function to transform elements and their indices.

array

Type: 'T []

The input array.

The array of transformed elements.

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

The following code demonstrates the use of Array.mapi.

F#
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let array1 = [| 1; 2; 3 |]
let newArray = Array.mapi (fun i x -> (i, x)) array1
printfn "%A" newArray

Output 

[|(0, 1); (1, 2); (2, 3)|]

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

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

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