Convert multi-dimensional array into matrix-like array

Question

I have the following array:

$array = array(
    array("2018","2019"),
    "Jan",
    array("France","Germany")
);

I need a matrix that crosses all the elements of the array; e.g:

array(
    array("2018","Jan","France"),
    array("2018","Jan","Germany"),
    array("2019","Jan","France"),
    array("2019","Jan","Germany")
);

meaning, 2 x 2 x 1 arrays

but this can be that I have more elements that are or are not arrays then:

$array = array(
    array("2018","2019"),
    "Jan",
    array("France","Germany"),
    array("prod1","prod2","prod3"),
    'Act'
);

In this case I would get 2 x 2 x 1 x 4 x 1 arrays in the end.

Any idea on how to achieve this?

not yet, I am rather looking for an orientation thus. I wonder whether loops would work since the number of arrays can be variable — laloune, Aug 07 '17 at 14:14
You can loop through the main array and detect the whether each element is array. Maybe you can try a recursion.... — lvil, Aug 07 '17 at 14:15
I think recursion is the easiest solution. Have a look here https://stackoverflow.com/questions/8567082/how-to-generate-in-php-all-combinations-of-items-in-multiple-arrays this might help you — ᴄʀᴏᴢᴇᴛ, Aug 07 '17 at 14:17
Possible duplicate of [How to generate in PHP all combinations of items in multiple arrays](https://stackoverflow.com/questions/8567082/how-to-generate-in-php-all-combinations-of-items-in-multiple-arrays) — ᴄʀᴏᴢᴇᴛ, Aug 07 '17 at 14:19

Sarkouille · Accepted Answer · 2017-08-07T14:37:30.840

Is that what you are looking for ?

$dst = array(array());
foreach ($array as $idx => $val) {
    foreach ($dst as $tmp_idx => $tmp_array) {
        if (is_array($val)) {
            foreach ($val as $sub_idx => $sub_val) {
                $dst[] = array_merge($dst[$tmp_idx], array(count($dst[$tmp_idx]) => $sub_val));
            }
        } else {
            $dst[] = array_merge($dst[$tmp_idx], array(count($dst[$tmp_idx]) => $val));
        }
        unset($dst[$tmp_idx]);
    }
}

I declare the array with an empty array in it.
A first foreach iterates through the main array to access all the categories, whatever their number.
A second foreach iterates through the result array.
A third foreach - or not, depending if the category contains several or a single entry - iterates through each entry of the current category and merges an array containing only that current category in the result currently iterated on (from $dst). The merge is pushed into the result array. The result stored in $dst are assumed to be temporary and will be copied and completed with each new value, making them progressively contain one entry from each category.
At the end of each iteration on $dst, the current temporary result is removed from the array since it has no purpose : if the foreach iterated on it, that means that it was incomplete.
At the end, the only entries in $dst that remain are these who weren't iterated on, meaning that every entry from each category were considered when they were created, meaning that they are complete.
I'm available for any clarification may the need arise.

I guess it can be optimised, especially regarding the `unset()` part, but I haven't slept for a day and a half and answer from work, I believe my brains are a little off. — Sarkouille, Aug 07 '17 at 14:25
While this code may answer the question, providing additional context regarding why and/or how this code answers the question improves its long-term value. — ᴄʀᴏᴢᴇᴛ, Aug 07 '17 at 14:27
@ᴄʀᴏᴢᴇᴛ I fully agree with that, I'm definitely dizzy, my apologies. — Sarkouille, Aug 07 '17 at 14:29
this is definitely what I am looking for. Thanks a lot. I will analyze it further to understand what it does step by step. — laloune, Aug 07 '17 at 14:32
@laloune I'm deeply sorry for the lack of explaination about what the code does/how it works. I've fixxed that. — Sarkouille, Aug 07 '17 at 14:38
gee thanks a bunch ksjohn for this complete explanation! this brings a lot of value added — laloune, Aug 10 '17 at 13:08

Convert multi-dimensional array into matrix-like array

1 Answers1