Weird code Hiccup

[witherton]

I am using the following code in a project. It runs in two parts. The first randomizes the numbers 0-2.

The second part randomized the numbers 0-2 so that none of the numbers in the first set match the number in the second set. For example, if the first number in the first part is "1", then the second part will only return "0" or "2" in the first position.

The code works how I'd like it to work, except one out of maybe 15 times, the function skips the first part of the code and goes straight to the second part causing an overflow. Why does the code occasionally skip the first part?

var pi=3;

var t1:Array=[0,1,2];

var t2:Array=new Array();

var trasher:Array=new Array();

chooseThem()

function chooseThem():void

{for (var j:uint=0;j<3;j++)

     {trace ("working");

     var m=Math.floor(Math.random()*pi);

     t1.push(t1);

     trasher.push(t1);

     t1.splice(m,1);

     pi-=1};

for (var q:uint=0;t2.length<3;q++)

     {var f=Math.floor(Math.random()*trasher.length);

     trace (trasher.length+"trasher");

     if (trasher!=t1[pi]) {t2.push(trasher);trasher.splice(f,1);pi+=1}

     }

trace (t1);trace (t2+"t2")}

[kglad]

you can use:

var t1:Array = [0,1,2];

var t2:Array = t1.slice();;

shuffle(t1);

shuffleExcept(t2,t1);

// don't change anything below

function shuffle(a:Array) {

    var p:int;

    var t:*;

    var ivar:int;

    for (ivar = a.length-1; ivar>=0; ivar--) {

        p=nextIndexF(ivar);

        t = a[ivar];

        a[ivar] = a

;

        a

= t;

    }

}

function shuffleExcept(a:Array,b:Array) {

    var p:int;

    var t:*;

    var ivar:int;

    for (ivar = a.length-1; ivar>=0; ivar--) {

        p = nextIndexF(ivar);

        while(a

==b[ivar]){

            p = nextIndexF(ivar);

        }

        t = a[ivar];

        a[ivar] = a

;

        a

= t;

    }

}

function nextIndexF(ivar:int):int{

    return Math.floor((ivar+1)*Math.random());

}

[witherton]

Thanks for the rresponse. I really appreciate it.

Do you have any idea why the the the first part of the code I posted is sometimes dropped? It's not just that it's not working properly. I have a trace statement right at the beginning of the first part and even that doesn't trace.

[kglad]

i didn't check your code any further than to see it was a bit of a mess and it would be easier to start from scratch and code it more logically.

[witherton]

Thanks for the response. I actually get the exact same error message when testing your code as I got when testing mine, so I am not sure what aspect of that was easier. I  was curious because both pieces of code might contain the same error.

[kglad]

i see the problem.  you can't really randomize when evaluating the last two array elements.

use:

function shuffleExcept(a:Array,b:Array) {

    var p:int;

    var t:*;

    var ivar:int;

    for (ivar = a.length-1; ivar>=2; ivar--) {

        p = nextIndexF(ivar);

        while(a

==b[ivar]){

            p = nextIndexF(ivar);

        }

        t = a[ivar];

        a[ivar] = a

;

        a

= t;

    }

    if(a[1]==b[1] || a[0]==b[0]){

        t = a[1];

        a[1] = a[0];

        a[0] = t;

    }

}

[witherton]

Thanks for the reply, but the compiler error returns "Call to a possibly undefined method nextIndexF." One of the advantages of troubleshooting code as opposed to creating all new code is that the asker is likelier to understand  the original code and will be able to play around with problems like this. While my original code was not elegant, I understood what it did. I have no idea what nextIndexF is a reference to or should do and won't figure it out until the code works properly and I can pplay around with each part of the code.  In some cases it would definitely be helpful to introduce all new code, however, in this case, I was more interested in finding out what was causing this unusual problem as opposed to shoving in some code that I didn't understand to get the job done. Once I understood the problem, I would have been able to come up with more streamlined code.

[kglad]

use the same code i already suggested but replace the shuffleExcept function.