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