php如何查询数组重复的值

$numbers = array(1, 2, 3, 2, 5, 1, 3, 2, 1);
$unique = array_unique($numbers);
$counts = array_count_values($numbers);
$repeats = array();
foreach ($unique as $value) {
  if ($counts[$value] > 1) {
    $repeats[] = $value;
  }
}
print_r($repeats);