Transpose an associative 2d array

i have an array like this

Array
(
    [url_pic] => Array
        (
            [1001] => lvTbHafU1L2gqnmuSVMrWZzkcGJxORFs.jpg
            [1002] => Da0qf3yKRglNewH6X5n9zShLGubZVQtx.jpg
            [1003] => SGdQJ8h5CjHPkEbYpF9oglatsTfyc0nA.jpg
            [1004] => fikemigfeof330.gif
            [1005] => 7a5083ou41269s.jpg
        )

    [url_post] => Array
        (
            [1001] => http://google.com
            [1002] => http://google.com
            [1003] => http://google.com
            [1004] => http://google.com
            [1005] => http://google.com
        )

    [sort_pic] => Array
        (
            [1001] => 444
            [1002] => 777
            [1003] => 777
            [1004] => 100
            [1005] => 888
        )
        
)   

i want to change sort of it like this :

Array
(
    [1001] => Array
        (
            [url_pic] => lvTbHafU1L2gqnmuSVMrWZzkcGJxORFsjpg
            [url_post] => http://google.com
            [sort_pic] => 444
        )

    [1002] => Array
        (
            [url_pic] => Da0qf3yKRglNewH6X5n9zShLGubZVQtxjpg
            [url_post] => http://google.com
            [sort_pic] => 777
        )
.......

)

it works well with this code : $set_name = array();

foreach ( $result2 as $db_keys => $db_values ) {
    //$set_name[] = $db_keys;

    foreach ( $db_values as $final_key => $final_value ) {
        $final_value_all[$final_key][$db_keys] = $final_value;
        // $final_value_all[$final_key][$set_name] = $final_value;
    }
}

I have no problem with upper code but I have a question about my commented lines

I write $db_keys into $set_name so $set_name output will be :

Array
(
    [0] => url_pic
    [1] => url_post
    [2] => sort_pic
)

When I want to use $set_name in $final_value_all[$final_key][$set_name] = $final_value;

I got this error: Warning: Illegal offset type

why I can't use$set_name in $final_value_all[$final_key][$set_name] = $final_value; ?

note : I know it's not necessary to use it, but I want to understanding why I can't use it.

your $set_name is array if you want to use this

do it

$final_value_all[$final_key][$set_name[sizeof($set_name)-1]] = $final_value;

because

$set_name[sizeof($set_name)-1] will be equals to you $db_keys