使多维数组唯一并保持其结构

Question

I got a multidimensional array that holds multiple session ID's and an array of field data and looks like this:

Array 
(
    [102] => Array
        (
            [session_id] => A11.. etc
            [fields] => Array
                (
                    [0] => Array
                        (
                            [date_time] => 2013-03-25 16:28:56
                            [ip_address] => xx.xxx.x.xxx
                            [user_name] => public.static
                            [session_type] => Start
                        )

                    [1] => Array
                        (
                            [date_time] => 2013-03-25 16:28:56
                            [ip_address] => xx.xxx.x.xxx
                            [user_name] => public.static
                            [session_type] => Start
                        )

As you can see, the first 2 field array records hold the same data. So far I have written the following piece of PHP code to make it unique and sort it by date.

for($i = 0; $i<count($unsortedOutput); $i++) {
    usort($unsortedOutput[$i]['fields'], 'sortFunction');
    $unique[] = array_map('unserialize', array_unique(array_map('serialize', $unsortedOutput[$i]['fields'])));
}

This works but when i print the $unique array, it (as expected) removes the [session_id] and [fields] keys:

Array 
(
    [102] => Array
        (
            [0] => Array
                (
                    [date_time] => 2013-03-25 16:28:56
                    [ip_address] => 94.229.1.233
                    [user_name] => public.static
                    [session_type] => Start
                )

My question is:

How do I make my multidimensional array unique while keeping the whole structure. I feel I'm close, but can't figure out the rest.

Answer 1

As an alternative, you could also use foreach with & reference to each copy to make changes:

foreach($unsortedOutput as &$o) {
    usort($o['fields'], 'sortFunction');
    $o['fields'] = array_map('unserialize', array_unique(array_map('serialize', $o['fields'])));
}