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

Here is a code that generates unique combinations from a set of numbers.

If you have a list of numbers, like 1,3,4,7,12 you can generate sets of X numbers, all unique, no repetitive.

The first function works in PHP 7.4 or higher, and the second one uses keys to store the values. Both work very well based on the benchmark.

function get_combos74($map, $size, &$generated = [], $loop = 1, $i = 0, $prefix = [])
{
    if ($loop == 1) {
        sort($map);
    }

    for (; $i < count($map); $i++) {
        if ($loop < $size) {
            get_combos74($map, $size, $generated, $loop + 1, $i + 1, [...$prefix, $map[$i]]);
        } else {
            $generated[] = [...$prefix, $map[$i]];
        }
    }

    return $generated;
}

function get_combosSTR($map, $size, &$generated = [], $loop = 1, $i = 0, $prefix = '')
{
    if ($loop == 1) {
        sort($map);
    }

    for (; $i < count($map); $i++) {
        if ($loop < $size) {
            get_combosSTR($map, $size, $generated, $loop + 1, $i + 1, "$prefix{$map[$i]}:");
        } else {
            $generated["$prefix{$map[$i]}"] = 0;
        }
    }

    return $generated;
}