PHP array_merge memory limit - Optimise function

[GavinHolt]

Hi All,

I have coded a function to work out all the possible combinations givien a list of properties and options. If the script was working out all the possible ways people would like toast, it might look like this.

Array
(
    [Bread] => Array
        (
            [0] => White
            [1] =>  Wholemeal
        )

    [Colour] => Array
        (
            [0] => Lightly Toasted
            [1] =>  Well Toasted
            [2] =>  Burnt
        )

    [Butter] => Array
        (
            [0] => Yes
            [1] => No
        )

    [Jam] => Array
        (
            [0] => None
            [1] => Strawberry
            [2] => Raspberry
            [3] =>  Lemon & Lime
        )

)

The Function is

function combinations($elements) {
	if(is_array($elements)){
		$combinations=array(array());
		foreach($elements as $key=>$value){
			foreach ($value as $k=>$element){
				$new_combinations=array();
				foreach ($combinations as $combination) {
					$tmp = array($key=>$k);
					$new_combination=array_merge($combination,$tmp);
					unset($tmp,$combination);
					array_push($new_combinations,$new_combination);
					unset($new_combination);
				}
				$combinations=array_merge($combinations,$new_combinations);
			}		
		}
		for($j=0;$j<count($elements);$j++){
			for($i=0;$i<count($combinations);$i++){
				if((count($combinations[$i]))<(count($elements))){
					unset($combinations[$i]);
				}
			}
			$combinations = array_values($combinations);
		}
		return array_values(array_unique($combinations));
	}
	else{
		return false;
	}
}

If more than roughyly 6 options with 3 properties each are given, the function fails giving a memory limit error on either array_merge lines.
Do any of you clever people have any suggestions on how to improve this function and make it more efficent?

TIA for the advice!

[blocblue]

Firstly, you could try passing your arrays by reference, rather than duplicating them in memory. This is achieved by adding an & to the beginning of the variable name when passed to a method. E.g. &$arrElement Also, you could simply increase the memory limit allocated to PHP... you can find how to do this here.

Regards,
R.

[GavinHolt]

Firstly, you could try passing your arrays by reference, rather than duplicating them in memory. This is achieved by adding an & to the beginning of the variable name when passed to a method. E.g. &$arrElement Also, you could simply increase the memory limit allocated to PHP... you can find how to do this here.

Regards,
R.

Thanks for the reply!
I have never seen the byRef method in php (Seen it back in good 'ol VB6 :p). Learn something new everyday!

I have gave it a whirl and its still bumming out in the same place. I have root access to the server, but its a live customer hosting server and would rather not go down the mem increase line if possible.

I think the secret will be in optimising the code.

[gate7cy]

I am having the same error coming up. The code I am using I got it from the php cookbook. The code is fine and optimised. Tried also to increase the memory limit but still the same error. Anyone has worked this out/??