Putting array values as keys in deeper levels

[lwc]

I think I better demonstrate my problem in code:
[code]$string = 'level0a=>level1a=>level2a=>level3a';
$array = explode('=>', $string);
print_r($array);
Array
(
    [0] => level0a
    [1] => level1a
    [2] => level2a
    [3] => level3a
)[/code]

The problem is I want it to look like:
[code]Array
(
[level0a] => Array
             (
              [level1a] => Array
                           (
                           [level2a] => Array
                                        (
                                        [level3a] => Array
                                                     (
                                                     )
                                         )
                           )
             )
)

)[/code]

I stress the [b]"a"[/b] (e.g. "level0[b]a[/b]") because I many of these strings and that's why I need each "level" to be an array.

For example:
[code]$string1 = 'level0a=>level1a=>level2a=>level3a';
$string2 = 'level0b=>level1b=>level2b=>level3b';
$string3 = 'level0c=>level1c';
$string4 = 'level0d=>level1d=>level2d';[/code]

So is there an easy way to do it?

Thanks!

[lwc]

And of course they could collide:
[code]$string5 = 'level0a=>level1b';
$string6 = 'level0b';
$string7 = 'level0a=>level1a=>level2b';[/code]

[Accipiter]

Reading your question, I was slightly confused in what you tried to do (eventhough it was thouroughly explained).
The point which I wasn't sure about was:

When you say 'collide', do you mean you want the same value to be accessed both through the [color=blue]level0a[/color] array as well as through the [color=blue]level0b[/color] array?

I mean, do you want:

[code]$list['level0a']['level1a']['level2b'] = 12;

echo $list['level0b']['level1b']['level2b'];[/code]

to show the value: [color=blue]12[/color]

Or will the information stored under one of the branches in this array only be accessible through that branch?