data yang tampil [object object]

permisi para suhu, saya sedang menggunakan datatable dicodeigniter, dan sepertinya penerapan query saya ada yg salah karena data yg tampil selalu [object object]. berikut script yg saya gunakan

public function ajax_list_peneliti_perpostingan()
	{

		$list = $this->post->get_datatables_peneliti_perpostingan();
		$data = array();
		$no = $_POST['start'];
		foreach ($list as $post) {
			$no++;

			$query = $this->db->query('SELECT count(postedby) FROM peneliti where postedby = "'.$post->postedby.'"');
			$row_count = $query->result_array();

			$row = array();
			$row[] = $post->postedby;
			$row[] = $row_count['0'];

			$data[] = $row;
		}

		$output = array(
						"draw" => $_POST['draw'],
						"recordsTotal" => $this->post->count_all_peneliti_perpostingan(),
						"recordsFiltered" => $this->post->count_filtered_peneliti_perpostingan(),
						"data" => $data,
				);
		//output to json format
		echo json_encode($output);
	}

pada saya menampilkan variable $row_count[] = data yg muncul selalu object.. kira2 penerapan dimana yg saya salahnya. Thanks

dan ini data yg muncul pada consolenya

{"draw":"2","recordsTotal":481,"recordsFiltered":481,"data":[["administrator",{"count(postedby)":"1"}],["fadil",{"count(postedby)":"25"}],["",{"count(postedby)":"1"}],["tilan",{"count(postedby)":"160"}],["Editor",{"count(postedby)":"2"}],["budi",{"count(postedby)":"1"}],["admin",{"count(postedby)":"291"}]]}