Remove duplicated elements of associative array in PHP

Question

$result = array(     0=>array('a'=>1,'b'=>'Hello'),     1=>array('a'=>1,'b'=>'other'),     2=>array('a'=>1,'b'=>'other'), ); 

If it is duplicated removed it, so the result is as follows:

$result = array(     0=>array('a'=>1,'b'=>'Hello'),     1=>array('a'=>1,'b'=>'other')    ); 

Could any know to do this?

Thanks

Answer 1

Regardless what others are offering here, you are looking for a function called array_unique^Docs. The important thing here is to set the second parameter to SORT_REGULAR and then the job is easy:

array_unique($result, SORT_REGULAR); 

The meaning of the SORT_REGULAR flag is:

compare items normally (don't change types)

And that is what you want. You want to compare arrays^Docs here and do not change their type to string (which would have been the default if the parameter is not set).

array_unique does a strict comparison (=== in PHP), for arrays this means:

$a === $b TRUE if $a and $b have the same key/value pairs in the same order and of the same types.

Output (Demo):

Array (     [0] => Array         (             [a] => 1             [b] => Hello         )      [1] => Array         (             [a] => 1             [b] => other         ) ) 

Answer 2

First things first, you can not use plain array_unique for this problem because array_unique internally treats the array items as strings, which is why "Cannot convert Array to String" notices will appear when using array_unique for this.

So try this:

$result = array(     0=>array('a'=>1,'b'=>'Hello'),     1=>array('a'=>1,'b'=>'other'),     2=>array('a'=>1,'b'=>'other') );  $unique = array_map("unserialize", array_unique(array_map("serialize", $result)));  print_r($unique); 

Result:

Array (     [0] => Array         (             [a] => 1             [b] => Hello         )      [1] => Array         (             [a] => 1             [b] => other         )  ) 

Serialization is very handy for such problems.

If you feel that's too much magic for you, check out this blog post

function array_multi_unique($multiArray){    $uniqueArray = array();    foreach($multiArray as $subArray){      if(!in_array($subArray, $uniqueArray)){       $uniqueArray[] = $subArray;     }   }   return $uniqueArray; }  $unique = array_multi_unique($result);  print_r($unique); 

Ironically, in_array is working for arrays, where array_unique does not.