Question

I’ve two arrays, the first ($needles) containing a bunch of Objects, the second ($stack) containing a bunch of key/values, but where one value is an array of Objects similar to the first array.

How can I delete all Objects within the target_p value in $stack where c_id matches any of the objects in $needle?

Thanks

Array ($needles)
(
    [0] => stdClass Object
        (
            [c_id] => 305164
            [neg] => 
            [seconds] => 604800
            [f_min] => 10
        )

    [1] => stdClass Object
        (
            [c_id] => 305165
            [neg] => 
            [seconds] => 604800
            [fr_min] => 10
        )

    [2] => stdClass Object
        (
            [c_id] => 305166
            [neg] => 
            [seconds] => 604800
            [f_min] => 10
        )

)
*****************
Array ($stack)
(
    [req_all] => 
    [target_p] => Array
        (
            [0] => stdClass Object
                (
                    [c_id] => 305164
                    [pid] => 2323554
                    [neg] => 
                    [seconds] => 
                    [f_min] => 
                )

            [1] => stdClass Object
                (
                    [c_id] => 305165
                    [pid] => 1964608
                    [neg] => 
                    [seconds] => 
                    [f_min] => 
                )

            [2] => stdClass Object
                (
                    [c_id] => 305166
                    [neg] => 1
                    [seconds] => 604800
                    [f_min] => 
                )

            [3] => stdClass Object
                (
                    [c_id] => 305167
                    [neg] => 1
                    [seconds] => 604800
                    [f_min] => 
                )

            [4] => stdClass Object
                (
                    [c_id] => 314022
                    [pid] => 4950148
                    [neg] => 
                    [seconds] => 
                    [f_min] => 
                )

        )

    [logical_e] => 
)

Desired output:

Array ($stack)
(
    [req_all] => 
    [target_p] => Array
        (
            [0] => stdClass Object
                (
                    [c_id] => 305167
                    [neg] => 1
                    [seconds] => 604800
                    [f_min] => 
                )

            [1] => stdClass Object
                (
                    [c_id] => 314022
                    [pid] => 4950148
                    [neg] => 
                    [seconds] => 
                    [f_min] => 
                )

        )

    [logical_e] => 
)

Answer 1

Without rebuilding an array? Not really. But it’s still easy.

Rebuild the needles array with keys matching the c_id values:

$o_needles = array();
foreach ($needles as $needle) {
    $o_needles[$needle->c_id] = $needle;
}

Then remove any nodes in the stack that has a c_id value matching a key in the modified needles array:

foreach ($stack['target_p'] as $key => $obj) {
    if (array_key_exists($obj->c_id, $o_needles)) {
        unset($stack['target_p'][$key]);
    }
}

The performance/complexity is O(n + m).

If you were to use a function like array_map, array_walk, array_filter or a nested foreach, you’d have to look over each of the needles for each element in the stack, which would be less efficient, especially with large datasets (O(n * m)).