Comments on snippet: 'Unique Random Array'

cessnajumpin said on 27/Aug/2009

Thu, 27 Aug 2009 14:31:02 UTC

Hahaha......wow. You may want to take another look there. Shuffle does nothing other than return a -1,0, or 1 to be used with the sort function (and that function is well documented by Adobe, probably because it's one of theirs). Amazingly, arrays can contain strings! I know it's a simple concept, but can understand how that could be confusing. Anyways, there's nothing wrong with my code.

GillesL said on 20/Feb/2011

Sun, 20 Feb 2011 22:01:51 UTC

This function works but one should know that it doesn't produce an even randomization. In the exemple above, the array length is 6, so each item should have a probability of 1/6 to be found at any place in the randomized result. It's not the case. Here is a little test I built to convince myself : function shuffle($a:Array):Array { return $a.sort( function ($a,$b):int { var sortNum : int = Math.round(Math.random() * 2) - 1; return sortNum; }); } var count:Array = [[0,0,0,0,0],[0,0,0,0,0],[0,0,0,0,0],[0,0,0,0,0],[0,0,0,0,0]]; var tmp:Array; for (var i=0; i



GillesL said on 20/Feb/2011
Sun, 20 Feb 2011 22:10:48 UTC
OK comments are too short for my explanation so here's the conclusion : don't use this function if you want an even randomization of your array. I wrote a snippet for the full explanation: http://snipplr.com/view/49292/beware-with-array-shuffle-function/