Transform flat array into a hierarchical, multi-dimensional array

Question

I have a standard array with key-value pairs - and I want to use the keys to transform it into a multi-dimensional array. The difficulty seems to be that I need to loop recu

Answer 1

You can use a reference while walking though the array hierarchy levels:

function array_flat_to_multidimensional($arr) {
    $out = array();
    foreach ($arr as $compoundKey => $val) {
        $ref = &$out;
        foreach (explode(".", $compoundKey) as $key) {
            if (!array_key_exists($key, $ref)) $ref[$key] = array();
            $ref = &$ref[$key];
        }
        $ref = $val;
    }
    unset($ref);
    return $out;
}