Array Shuffle

Shuffling array using Seq.fold

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open System

let rng = new Random()

let Shuffle (org:_[]) = 
    let arr = Array.copy org
    let max = (arr.Length - 1)
    let randomSwap (arr:_[]) i =
        let pos = rng.Next(max)
        let tmp = arr.[pos]
        arr.[pos] <- arr.[i]
        arr.[i] <- tmp
        arr
   
    [|0..max|] |> Array.fold randomSwap arr


[|1..30|] |> Shuffle |> printfn "%A"
[|"F#";"C#";"Haskell";"JavaScript";"Erlang"|] |> Shuffle |> printfn "%A"

namespace System

val rng : Random

Full name: Script.rng

Multiple items
type Random =
  new : unit -> Random + 1 overload
  member Next : unit -> int + 2 overloads
  member NextBytes : buffer:byte[] -> unit
  member NextDouble : unit -> float

Full name: System.Random

--------------------
Random() : unit
Random(Seed: int) : unit

val Shuffle : org:'a [] -> 'a []

Full name: Script.Shuffle

val org : 'a []

val arr : 'a []

type Array =
  member Clone : unit -> obj
  member CopyTo : array:Array * index:int -> unit + 1 overload
  member GetEnumerator : unit -> IEnumerator
  member GetLength : dimension:int -> int
  member GetLongLength : dimension:int -> int64
  member GetLowerBound : dimension:int -> int
  member GetUpperBound : dimension:int -> int
  member GetValue : [<ParamArray>] indices:int[] -> obj + 7 overloads
  member Initialize : unit -> unit
  member IsFixedSize : bool
  ...

Full name: System.Array

val copy : array:'T [] -> 'T []

Full name: Microsoft.FSharp.Collections.Array.copy

val max : int

property Array.Length: int

val randomSwap : ('b [] -> int -> 'b [])

val arr : 'b []

val i : int

val pos : int

Random.Next() : int
Random.Next(maxValue: int) : int
Random.Next(minValue: int, maxValue: int) : int

val tmp : 'b

val fold : folder:('State -> 'T -> 'State) -> state:'State -> array:'T [] -> 'State

Full name: Microsoft.FSharp.Collections.Array.fold

val printfn : format:Printf.TextWriterFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printfn

Raw view Test code New version

More information

Link:	http://fssnip.net/mr
Posted:	10 years ago
Author:	Karlkim Suwanmongkol
Tags:	array , shuffle , random , fold