Array Unique with Associative Array - Remove Duplicates

Question

I've got an associative array with some duplicate items. For example, I have:

 <? 
 $group_array = array('user_id'=>array(), 'user_first'=>array());

Which outputs something like below:

Array
 (
[user_id] => Array
    (
        [0] => 594
        [1] => 597
        [2] => 594
    )

[user_first] => Array
    (
        [0] => John
        [1] => James
        [2] => John
    )
)

I'd like to sanitize this entire array so that only the user John will show up once (based on user_id).

I've tried the following:

 <?php 
   $unique = array_unique($group_array);
   print_r($unique);

But it does not appear to work. Any other ideas how I can remove the duplicate items in the array?

Any help would be great!

Answer 1

Another approach would be to find the unique user_ids, and importantly their array keys, then keep only the corresponding values from each of the columns.

$group_array = array(
    'user_id'    => array(594,    597,     594,    598   ),
    'user_first' => array('John', 'James', 'John', 'John'),
);

// Find unique user_ids
$uniques = array_unique($group_array['user_id']);

// Keep only the uniques
foreach ($group_array as $column => $collection) {
    $group_array[$column] = array_intersect_key($collection, $uniques);
}

print_r($group_array);