Ordering when inserting in Nested Sets tree

[betazold]

Imagine you have Nested Sets tree, and you must to order it (by moving nodes) by some value (may be date, or some number value).

$a = array();
 
for ($i = 0; $i < 15; $i++) {
    $a[rand(1, 1000)] = rand(1, 50);
}
 
print_r($a);
 
asort($a);
$c = array_keys($a);
 
print_r($a);
 
$q = array();
 
foreach ($a as $key => $value) {
    $aKey = array_search($key, $c, true);
    if (isset($c[$aKey + 1])) {
         $bKey = $c[$aKey + 1];
         array_unshift($q, array($value, $key, $bKey));
    }
}
 
// proof-o-concept: how array can be created
$r = array($key => $value);
 
foreach ($q as $data) {
    echo vsprintf("Moved %s from index %d before %dn", $data);
    $r = array_replace(array($data[1] => $data[0]), $r);
}
 
print_r($r);