Question

usort and uasort use a comparison function which is slow because it must be computed every time a comparison is needed between to elements of an array. Other languages, like Python, let you sort an array using a key function which gets evaluated only once per element in the array. What’s the best way to do this in PHP?

Answer 1

function sort_with_keyfunc($array, $keyfunc) {
    $keys = array_map($keyfunc, $array); // get the keys for each item
    array_multisort($keys, $array); // sort $array according to the sorted keys
    return $array;
}

This also maintains key=>value pairs in associative arrays.