本例是按降序排，并取出前50
$
tagsList 为需要排序的数组
$tagArray = _array_sort($tagsList,"desc");
$tag = json_encode(array_slice($tagArray,0,50));
public function _array_sort($array, $type='asc'){
$result=array();
foreach($array as $var => $val){
$set=false;
foreach($result as $var2 => $val2){
if($set==false){
if($val>$val2 && $type=='desc' || $val<$val2 && $type=='asc'){
$temp=array();
foreach($result as $var3 => $val3){
if($var3==$var2) $set=true;
if($set){
$temp[$var3]=$val3;
unset($result[$var3]);
}
}
$result[$var]=$val;
foreach($temp as $var3 => $val3){
$result[$var3]=$val3;
}
}
}
}
if(!$set){
$result[$var]=$val;
}
}
return $result;
}