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

Question

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     )  ) 

Answer 1

Here is 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))); 

Answer 2

Since 5.2.9 you can use array_unique() if you use the SORT_REGULAR flag like so:

array_unique($array, SORT_REGULAR); 

This makes the function compare elements for equality as if $a == $b were being used, which is perfect for your case.

Output

Array (     [0] => Array         (             [0] => abc             [1] => def         )      [1] => Array         (             [0] => ghi             [1] => jkl         )      [2] => Array         (             [0] => mno             [1] => pql         )  ) 

Keep in mind, though, that the documentation states:

array_unique() is not intended to work on multi dimensional arrays.