How to generate in PHP all combinations of items in multiple arrays

Question

I\'im trying to find all combinations of items in several arrays. The number of arrays is random (this can be 2, 3, 4, 5...). The number of elements in each array is random

Answer 1

I got this from O'Relly (https://www.oreilly.com/library/view/php-cookbook/1565926811/ch04s25.html),

function pc_array_power_set($array) {
// initialize by adding the empty set
$results = array(array( ));

foreach ($array as $element)
    foreach ($results as $combination)
        array_push($results, array_merge(array($element), $combination));



   return $results;
}

Then call it using,

$set = array('A', 'B', 'C');
$power_set = pc_array_power_set($set);

That should do the trick!

Answer 2

One more idea:

$ar = [
    'a' => [1,2,3],
    'b' => [4,5,6],
    'c' => [7,8,9]
];

$counts = array_map("count", $ar);
$total = array_product($counts);
$res = [];

$combinations = [];
$curCombs = $total;

foreach ($ar as $field => $vals) {
    $curCombs = $curCombs / $counts[$field];
    $combinations[$field] = $curCombs;
}

for ($i = 0; $i < $total; $i++) {
    foreach ($ar as $field => $vals) {
        $res[$i][$field] = $vals[($i / $combinations[$field]) % $counts[$field]];
    }
}

var_dump($res);