private static function recurse($uids)
{
// Base Case
if (empty($uids)) {
return $uids;
}
// Loop over each user id
foreach ($uids as $uid) {
// Seed this cluster
$cluster = new Cluster($uid);
// Loop over each user id again
foreach ($uids as $uid2) {
// Add the user id if it is within the threshold
if ($uid == $uid2) {
continue;
}
$dist = self::distance($uid, $uid2);
if ($dist <= self::$threshold) {
$cluster->add_user($uid2);
}
}
// Only save this cluster if it is the largest one
if (!isset($max) || $cluster->size() > $max->size()) {
$max = $cluster;
}
unset($cluster);
}
// Remove cluster from uids
$uids = array_diff($uids, $max->users);
// Return all of the clusters
return array_merge(array($max), self::recurse($uids));
}