How can I check and delete duplicate arrays?

Question

how can I check and delete duplicate arrays?

Example:

$a = array(
   array(
      'id' => 1,
      'name' => 'test'
   ),
   // Next array is equal to first, then delete
   array(
      'id' => 1,
      'name' => 'test'
   ), 
   // Different array, then continue here
   array(
      'id' => 2,
      'name' => 'other'
   )
);

If the array is the same, then delete the duplicate and get only one array.

Answer 1

You can use a lookup table storing serialized arrays. If an array already exists in the lookup table, you have a duplicate and can splice out the key:

$a = array(
   array(
      'id' => 1,
      'name' => 'test'
   ),
   array(
      'id' => 1,
      'name' => 'test'
   ), 
   array(
      'id' => 2,
      'name' => 'other'
   )
);

$seen = [];

for ($i = count($a) - 1; $i >= 0; $i--) {
    if (array_key_exists(json_encode($a[$i]), $seen)) {
        array_splice($a, $i, 1);
    }
    else {
        $seen[json_encode($a[$i])] = 1;
    }
}

print_r($a);

Output:

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => test
        )

    [1] => Array
        (
            [id] => 2
            [name] => other
        )

)

Try it!