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Array.scan<'T,'State> Function (F#)

Den Delimarsky|Last Updated: 6/8/2016
|
1 Contributor

Like Array.fold, but returns the intermediate and final results.

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

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

Syntax

// Signature:
Array.scan : ('State -> 'T -> 'State) -> 'State -> 'T [] -> 'State []

// Usage:
Array.scan folder state array

Parameters

folder Type: 'State -> 'T -> 'State

The function to update the state given the input elements.

state Type: 'State

The initial state.

array Type: 'T[]

The input array.

Return Value

The array of state values.

Remarks

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

Example

The following code illustrates the use of Array.scan.


    let initialBalance = 1122.73
    let transactions = [| -100.00; +450.34; -62.34; -127.00; -13.50; -12.92 |]
    let balances =
        Array.scan (fun balance transactionAmount -> balance + transactionAmount) initialBalance transactions
    printfn "Initial balance:\n $%10.2f" initialBalance
    printfn "Transaction   Balance"
    for i in 0 .. Array.length transactions - 1 do
        printfn "$%10.2f $%10.2f" transactions.[i] balances.[i]
    printfn "Final balance:\n $%10.2f" balances.[ Array.length balances - 1]

Output

Initial balance:
$   1122.73
Transaction   Balance
$   -100.00 $   1122.73
$    450.34 $   1022.73
$    -62.34 $   1473.07
$   -127.00 $   1410.73
$    -13.50 $   1283.73
$    -12.92 $   1270.23
Final balance:
$   1257.31

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

Collections.Array Module (F#)

Microsoft.FSharp.Collections Namespace (F#)

© 2016 Microsoft