note 90567 added to function.usort

If you already have a sorted array and you want to add a new item, the obvious solution is to append the new item and then resort: <?php $already_sorted[] = $new_item; usort($already_sorted, 'sort_callback'); ?> However, the performance of this is horrible. usort has no way of knowing that the array you're passing it is already sorted (except for the one appended item). usort therefore will have to compare and resort the entire array, even though 99.99% of the work is already done. An alternative is this uisort function I wrote (uisort = user-insert-sort): <?php /** * insert an item into an already-sorted array * * given an $array that is already sorted via $cmp_function, * insert $insert_item in the correct position. does not * maintain index association. * * this is simply an efficient replacement for the following: * // this: * $array[] = $insert_item; * usort($array, $cmp_function); * * // becomes this: * uisort($array, $cmp_function, $insert_item); * * @param &$array the array in which to insert the new item. MUST BE already sorted via $cmp_function * @param $cmp_function the comparison function ({@link usort}) * @param $insert_item the item to insert * * @return bool on success returns true, otherwise false */ function uisort (&$array, $cmp_function, $insert_item) { if (! is_callable($cmp_function)) { user_error('uisort(): Invalid comparison function', E_USER_WARNING); return false; } $array = array_values($array); foreach ($array as $k => $existing_item) { if (($ret = call_user_func($cmp_function, $existing_item, $insert_item)) >= 0) { array_splice($array, $k, 0, array($insert_item)); return true; } } array_push($array, $insert_item); return true; } ?> ---- Server IP: 66.207.199.35 Probable Submitter: 69.70.125.250 ---- Manual Page -- http://www.php.net/manual/en/function.usort.php Edit -- https://master.php.net/note/edit/90567 Del: integrated -- https://master.php.net/note/delete/90567/integrated Del: useless -- https://master.php.net/note/delete/90567/useless Del: bad code -- https://master.php.net/note/delete/90567/bad+code Del: spam -- https://master.php.net/note/delete/90567/spam Del: non-english -- https://master.php.net/note/delete/90567/non-english Del: in docs -- https://master.php.net/note/delete/90567/in+docs Del: other reasons-- https://master.php.net/note/delete/90567 Reject -- https://master.php.net/note/reject/90567 Search -- https://master.php.net/manage/user-notes.php