二维数组去重

$arr = [
    [‘a‘=>1,‘s‘=>2],
    [‘a‘=>1,‘s‘=>2],
    [‘a‘=>2,‘s‘=>2],
];

function arr2($arr){
 foreach ($arr as $k=>$v){
  $v=join(‘,‘,$v); //降为一维数组
  $temp[$k]=$v;    
 }
 $temp=array_unique($temp);  //取唯一值
 $s =array();
 foreach ($temp as $k => $v){
  $array=explode(‘,‘,$v); 
  $s[$k][‘a‘] = $array[0];
 }
 return $s;
}