How to remove duplicate values from a multi-dimensional array in PHP

How can I remove duplicate values from a multi-dimensional array in PHP?

Example array:

Array
(
    [0] => Array
 (
     [0] => abc
     [1] => def
 )

    [1] => Array
 (
     [0] => ghi
     [1] => jkl
 )

    [2] => Array
 (
     [0] => mno
     [1] => pql
 )

    [3] => Array
 (
     [0] => abc
     [1] => def
 )

    [4] => Array
 (
     [0] => ghi
     [1] => jkl
 )

    [5] => Array
 (
     [0] => mno
     [1] => pql
 )

)

From stackoverflow

• The user comments on the array_unique() documentation have many solutions to this. Here is one of them:

  kenrbnsn at rbnsn dot com
  27-Sep-2005 12:09

  Yet another Array_Unique for multi-demensioned arrays. I've only tested this on two-demensioned arrays, but it could probably be generalized for more, or made to use recursion.

  This function uses the serialize, array_unique, and unserialize functions to do the work.

      function multi_unique($array) {
          foreach ($array as $k=>$na)
              $new[$k] = serialize($na);
          $uniq = array_unique($new);
          foreach($uniq as $k=>$ser)
              $new1[$k] = unserialize($ser);
          return ($new1);
      }

  This is from http://ca3.php.net/manual/en/function.array-unique.php#57202.

• Another way. Will preserve keys as well.

  function array_unique_multidimensional($input)
  {
      $serialized = array_map('serialize', $input);
      $unique = array_unique($serialized);
      return array_intersect_key($input, $unique);
  }
  

• Here is another, another way. No intermediate variables are saved.

  We used this to de-duplicate results from a variety of overlapping queries.

  $input = array_map("unserialize", array_unique(array_map("serialize", $input)));
  

• An easy to read solution, probably not the most efficient:

  function arrayUnique($myArray){
      if(!is_array($myArray))
          return $myArray;
  
      foreach ($myArray as &$myvalue){
          $myvalue=serialize($myvalue);
      }
  
      $myArray=array_unique($myArray);
  
      foreach ($myArray as &$myvalue){
          $myvalue=unserialize($myvalue);
      }
  
      return $myArray;
  
  }