array_vertical - create arrays comprised of same index position elements of original arrays

gistfile1.txt

function array_vertical($source) {
  $keys = array_keys($source);
  $arr = array_values($source);
  $cut = array_map(null, ...$arr);
  foreach($cut as &$el) {
    $el = array_combine($keys, $el);
    $el = array_filter($el, function($v) {return ! is_null($v);});
  }
  return $cut;
  $cut=[];
  while (count($source)) {
        // definition collector
        $el = [];
        foreach($source as $k => &$v) { // &$v need to be reference for array_shift 
          // no more definitions
          if (empty($v)) {
            // shorten life of while cycle here
            unset($source[$k]);
            continue;
          }
          // collect only first
          $el[$k] = array_shift($v);
        } 
        if (! empty($el)) $cut[] = $el;
  }
  return $cut;
}