如何在Codeigniter中统计每个用户并返回数组

class User_model extends CI_Model {
    public function count_users() {
        $this->db->select('user_id, COUNT(*) as count');
        $this->db->from('users');
        $this->db->group_by('user_id');
        $query = $this->db->get();
        return $query->result_array();
    }
}

class User extends CI_Controller {
    public function index() {
        $this->load->model('user_model');
        $user_stats = $this->user_model->count_users();
        print_r($user_stats);
    }
}