Rangking nilai di codeigniter

saya mau membuat rangking nilai dari hasil penjumlahan seluruh nilai yang diperoleh

<?php
$uri = $this->uri->segment_array();
if(isset($uri[3])){
    if($uri[3] == 'review_rapor'){
        $border = '';
        $class = 'table table-bordered';
    } else {
        $border = 'border="1"';
        $class = 'table';
    }
}
$data['s'] = $this->siswa->get($siswa_id);
$sekolah = $this->sekolah->get($sekolah_id);
$setting = $this->settings->get(1);
$data['rombel'] = $this->rombongan_belajar->get($rombel_id);
$ajaran = $this->semester->get($ajaran_id);
$data['mapel_a'] = $this->pembelajaran->with('mata_pelajaran')->find_all("kelompok_id = 6 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_id IS NOT NULL OR kelompok_id = 6 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_pengajar_id IS NOT NULL", '*','no_urut ASC');
foreach($data['mapel_a'] as $mapela){
	$mapel_a_id[] = $mapela->mata_pelajaran_id;
}
if(isset($mapel_a_id)){
	$mapel_agama = array(100011070, 100012050, 100013010, 100014140, 100015010, 100016010);
	$data['mapel_a'] = filter_agama_mapel($ajaran_id,$mapel_agama, $mapel_a_id,$data['s']->agama_id);
}
//test($mapel_a);
$data['mapel_b'] = $this->pembelajaran->with('mata_pelajaran')->find_all("kelompok_id = 7 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_id IS NOT NULL OR kelompok_id = 7 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_pengajar_id IS NOT NULL", '*','no_urut ASC');
$data['mapel_c1'] = $this->pembelajaran->with('mata_pelajaran')->find_all("kelompok_id = 8 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_id IS NOT NULL OR kelompok_id = 8 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_pengajar_id IS NOT NULL", '*','no_urut ASC');
$data['mapel_c2'] = $this->pembelajaran->with('mata_pelajaran')->find_all("kelompok_id = 9 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_id IS NOT NULL OR kelompok_id = 9 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_pengajar_id IS NOT NULL", '*','no_urut ASC');
$data['mapel_c3'] = $this->pembelajaran->with('mata_pelajaran')->find_all("kelompok_id = 10 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_id IS NOT NULL OR kelompok_id = 10 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_pengajar_id IS NOT NULL", '*','no_urut ASC');
$data['mapel_tambahan'] = $this->pembelajaran->with('mata_pelajaran')->find_all("kelompok_id = 99 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_id IS NOT NULL OR kelompok_id = 99 AND semester_id =  $ajaran_id AND  rombongan_belajar_id = '$rombel_id' AND guru_pengajar_id IS NOT NULL", '*','no_urut ASC');
$data['nama_kelompok_a'] = $this->kelompok->get(6);
$data['nama_kelompok_b'] = $this->kelompok->get(7);
$data['nama_kelompok_c1'] = $this->kelompok->get(8);
$data['nama_kelompok_c2'] = $this->kelompok->get(9);
$data['nama_kelompok_c3'] = $this->kelompok->get(10);
$data['check_2018'] = $check_2018;
if($check_2018){
	$judul_rapor = 'A.  Nilai Akademik';
} else {
	$judul_rapor = 'C.  Pengetahuan dan Keterampilan';
}
?>
<style type="text/css">
   .tiga {
   font-size: 12px;
   }
   .ttd {
   font-size: 13px;
   }
</style>
<div class="strong"><?php echo $judul_rapor; ?></div>
<table <?php echo $border; ?> class="<?php echo $class; ?>">
    <thead>
	<?php if($check_2018){?>
		<tr>
			<th class="tiga" style="vertical-align:middle;width: 2px;" align="center">No</th>
			<th class="tiga" style="vertical-align:middle;width: 200px;" align="center" class="text-center">Mata Pelajaran</th>
			<th align="center" class="text-center tiga">Pengetahuan</th>
			<th align="center" class="text-center tiga">Keterampilan</th>
			<th align="center" class="text-center tiga">Nilai Akhir</th>
			<th align="center" class="text-center tiga">Predikat</th>
		</tr>
	<?php } else { ?>
		<tr>
			<th class="tiga" style="vertical-align:middle;width: 2px;" align="center" rowspan="2">No</th>
			<th class="tiga" style="vertical-align:middle;width: 200px;" rowspan="2" align="center" class="text-center">Mata Pelajaran</th>
			<th colspan="4" align="center" class="text-center tiga">Pengetahuan</th>
			<th colspan="4" align="center" class="text-center tiga">Keterampilan</th>
		</tr>
		<tr>
			<th align="center" style="width:10px;" class="text-center tiga">KKM</th>
			<th align="center" style="width:10px;" class="text-center tiga">Angka</th>
			<th align="center" style="width:10px;" class="text-center tiga">Predikat</th>
			<th align="center" style="width:150px;" class="text-center tiga">Deskripsi</th>
			<th align="center" style="width:10px;" class="text-center tiga">KKM</th>
			<th align="center" style="width:10px;" class="text-center tiga">Angka</th>
			<th align="center" style="width:10px;" class="text-center tiga">Predikat</th>
			<th align="center" style="width:150px;" class="text-center tiga">Deskripsi</th>
		</tr>
  	<?php } ?>
    </thead>
    <tbody>
		<?php
		$count_a = count($data['mapel_a']);
		$count_b = count($data['mapel_b']);
		$count_c1 = 0;
		$count_c2 = 0;
		$count_c3 = 0;
		$this->load->view('backend/cetak/2017/a',$data);
		$data['i'] = $count_a + 1;
		$this->load->view('backend/cetak/2017/b',$data);
		//if($data['rombel']->tingkat != 12){
		$count_c1 = count($data['mapel_c1']);
		$count_c2 = count($data['mapel_c2']);
		$data['i'] = $count_a + $count_b + 1;
		$this->load->view('backend/cetak/2017/c1',$data);
		$data['i'] = $count_a + $count_b + $count_c1 + 1;
		$this->load->view('backend/cetak/2017/c2',$data);
		//}
		//if($data['rombel']->tingkat != 10){
		$count_c3 = count($data['mapel_c3']);
		$data['i'] = $count_a + $count_b + $count_c1 + $count_c2 + 1;
		$this->load->view('backend/cetak/2017/c3',$data);
		//}
		$data['i'] = $count_a + $count_b + $count_c1 + $count_c2 + $count_c3 + 1;
		$this->load->view('backend/cetak/2017/m',$data);
		?>
		<tr>
		<?php
		$total_nilai = 0;
		$jumlah_mapel = 0;
			foreach($data_mapel as $key=>$mapel){
					$nilai_value1	= get_nilai_akhir2_siswa($ajaran_id, $kompetensi_id=1, $rombel_id, $mapel->mata_pelajaran_id, $siswa_id);
					$nilai_value2	= get_nilai_akhir2_siswa($ajaran_id, $kompetensi_id=2, $rombel_id, $mapel->mata_pelajaran_id, $siswa_id);
					$total_nilai += $nilai_value1 + $nilai_value2;
					if($nilai_value1){
						$jumlah_mapel++;
					}
					if($nilai_value2){
						$jumlah_mapel++;
					}
				}
		$rata_nilai_rapor = $total_nilai / $jumlah_mapel;
		$jumlah_siswa_rombel = get_jumlah_siswa($rombel_id);
		$value = array($total_nilai);
		$ranking = array();
		foreach ($value as $k => $v){
    		array_push($ranking, $v);
		}

		?>
			<td height="30px;" colspan="5" align="center" class="strong tiga">Total Nilai (Pengetahuan + Keterampilan)</td>
			<td colspan="5" align="center" class="strong tiga" ><?php echo number_format($total_nilai,0,',','.'); ?></td>
		</tr>
		<tr>
			<td height="30px;" colspan="5" align="center" class="strong tiga" >Nilai Rata-rata</td>
			<td colspan="5" align="center" class="strong tiga" ><?php echo number_format($rata_nilai_rapor,0,',','.'); ?></td>
		</tr>
		<tr>
			<td height="40px;" colspan="5" align="center" class="strong tiga" >Peringkat</td>
////////////////saya mau memberikan rangking disini
<td colspan="5" align="center" class="strong tiga" ><?php echo $ranking[0], "  dari  ",$jumlah_siswa_rombel; ?></td>
		</tr>
	</tbody>
</table>