按拼音首字母排序

<?php
                $temp = array();
                // 按拼音首字母排序
                foreach($res as $key=>$val){
                    $index = $this->sortByPinyin($val['note_name']);
                    $temp[$index][] = $val; //先用中间变量数组，根据字母A B C..装着集合在一起的   
                }
                $list = array();
                foreach($temp as $k=>$v){
                    $list[$k]['index'] = $k;
                    $list[$k]['list'] = $v;
                }
                array_multisort($list); //用 array_multisort按键排序，也可用 ksort()
                // ksort($list);
                $list = array_values($list); //最后将键弄回数字的那些键 ， A, B ,C ... => 0, 1, 2....

    /**
     * [获取字符串的拼音首字母]
     * @param  [type] $str [description]
     * @return [type]      [description]
     */
    public function sortByPinyin($str)
    {
      if(empty($str)){
         return '';
      }
      $fchar = ord($str{0});
      if($fchar>=ord('A')&&$fchar<=ord('z')){
         return strtoupper($str{0});    
      } 
      $s1 = iconv('UTF-8','gb2312',$str);
      $s2 = iconv('gb2312','UTF-8',$s1);
      $s = $s2==$str?$s1:$str;
      $asc=ord($s{0})*256+ord($s{1})-65536;
      if($asc>=-20319&&$asc<=-20284) return 'A';
      if($asc>=-20283&&$asc<=-19776) return 'B';
      if($asc>=-19775&&$asc<=-19219) return 'C';
      if($asc>=-19218&&$asc<=-18711) return 'D';
      if($asc>=-18710&&$asc<=-18527) return 'E';
      if($asc>=-18526&&$asc<=-18240) return 'F';
      if($asc>=-18239&&$asc<=-17923) return 'G';
      if($asc>=-17922&&$asc<=-17418) return 'H';
      if($asc>=-17417&&$asc<=-16475) return 'J';
      if($asc>=-16474&&$asc<=-16213) return 'K';
      if($asc>=-16212&&$asc<=-15641) return 'L';
      if($asc>=-15640&&$asc<=-15166) return 'M';
      if($asc>=-15165&&$asc<=-14923) return 'N';
      if($asc>=-14922&&$asc<=-14915) return 'O';
      if($asc>=-14914&&$asc<=-14631) return 'P';
      if($asc>=-14630&&$asc<=-14150) return 'Q';
      if($asc>=-14149&&$asc<=-14091) return 'R';
      if($asc>=-14090&&$asc<=-13319) return 'S';
      if($asc>=-13318&&$asc<=-12839) return 'T';
      if($asc>=-12838&&$asc<=-12557) return 'W';
      if($asc>=-12556&&$asc<=-11848) return 'X';
      if($asc>=-11847&&$asc<=-11056) return 'Y';
      if($asc>=-11055&&$asc<=-10247) return 'Z';
      return null;
    }

最后的结果是：（下面是json的形式）

[
  {
    "index": "A",
    "list": [
      {
        "id": "6",
        "suid": "1",
        "note_name": "哎去"
      },
      {
        "id": "7",
        "suid": "1",
        "note_name": "abf"
      }
    ]
  },
  {
    "index": "B",
    "list": [
      {
        "id": "9",
        "suid": "1",
        "note_name": "标签2"
      }
    ]
  },
  {
    "index": "C",
    "list": [
      {
        "id": "1",
        "suid": "1",
        "note_name": "测试"
      }
    ]
  },
  {
    "index": "D",
    "list": [
      {
        "id": "3",
        "suid": "1",
        "note_name": "DSA"
      }
    ]
  }
]