simplebits.org

Here is the code snippet for generating random permutation of array:

var a:Array = new Array( 1, 2, 3, 4, 5, 6, 7, 8, 9 );

trace( "Array: " + a );

for ( var i:uint = 0; i < a.length; ++i )
{
    var j:int = Math.random()*i;
    var j:int = Math.random()*( i + 1 );

    // Swap a[i] and a[j]
    var temp:* = a[j];
    a[j] = a[i];
    a[i] = temp;
}

trace( "Permutation: " + a );

Update: fixed bug with finding index of item to swap – thanks for pointing that out Kevin!

Recently I needed seeded pseudo-random number generator for my Flex project. After searching I found three good articles with solution of that problem. Grant Skinner proposed use of BitmapData.noise() method. He also provides Parker-Miller psuedo-random number generator based on implementation by Michael Baczynski.

Useful links:

• Source Code: Seeded Random in ActionScript 3 by Grant Skinner,
• A good Pseudo-Random Number Generator (PRNG) by Michael Baczynski,
• SeededRandomizer. A Seed Based Pseudorandom Number Generator in Actionscript by Noel Billig.

Today I’ve tried to add simple Sprite instance to Flex Canvas using addChild() method, but it doesn’t work. Solution is very simple – use rawChildren.addChild().

⇥ Continued