Shuffle Array

Monkey Forums/Monkey Beginners/Shuffle Array

zxretrosoft

(Posted March) [#1]

Hello everyone!
Please, is in Monkey-X any way to do Randomize Array?
Thank you in advance! ;-)

Gerry Quinn

(Posted March) [#2]

I use the following - it's in my 'Generic' class so I can shuffle an array of anything (ints, strings, objects or whatever).

Usage:

Local arr:Int[] = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
Generic< Int >.Shuffle( arr )
---> [ 7 2 0 5 8 6 3 1 4 9 ]
Array is fully shuffled

Local arr:Int[] = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
Generic< Int >.Shuffle( arr, 3 )
---> [ 6 8 2 3 4 5 0 7 1 9 ]
Only the first three elements are random (e.g. if you wanted to get three random cards from a deck, but you don't care if the rest of the deck is shuffled yet.

Class Generic< T >

	' Shuffle an array (only the first nToShuffle elements are random if a value is given)
	Function Shuffle:Void( _arr:T[], nToShuffle:Int = -1 )
		Local len:Int = _arr.Length()
		Local nVals:Int = nToShuffle
		nVals = Min( nVals, len )
		If nVals < 0
			nVals = len
		End
		For Local i:Int = 0 Until nVals
			Local iSwap:Int = i + Rnd( len - i ) 
			Local tmp:T = _arr[ i ]
			_arr[ i ] = _arr[ iSwap ]
			_arr[ iSwap ] = tmp
		Next
	End
End

If you don't like generics, it should be easy enough to change it for an array of something particular. Or you could remove the nToShuffle option if you will never want that. And bear in mind that the results will depend on the seed of the random number generator.

zxretrosoft

(Posted March) [#3]

Yes, it works!! Thank you very much for your help! ;)