PHP remove value from multi dimensional array

Question

I have an array, $arr, which looks like this:

'sdb5' => [
 'filters' => [
 (int) 11 => [
 'find' => [
 (int) 0 => (int) 569
 ],
 'exclude' => [
 (int) 0 => (int) 89,
 (int) 1 => (int) 573
 ]
 ],
 (int) 86 => [
 'find' => [
 (int) 0 => (int) 49,
 (int) 1 => (int) 522,
 (int) 2 => (int) 803
 ],
 'exclude' => [
 (int) 0 => (int) 530,
 (int) 1 => (int) 802,
 (int) 2 => (int) 511
 ]
 ]
 ]
],

I've read Delete element from multidimensional-array based on value but am struggling to understand how to delete a value in an efficient way.

For example, let's say I want to delete the value 522. I'm doing it like this:

 $remove = 522; // value to remove
 foreach ($arr as $filters) {
 foreach ($filters as $filter) {
 foreach ($filter as $single_filter) {
 foreach ($single_filter as $key => $value) {
 if ($value == $remove) {
 unset($key);
 }
 }
 }
 }
 }

I couldn't work out from the above link how to do this because even though it's a multidimensional array, it doesn't have any sub-arrays like mine.

I also don't know how else to rewrite this without repeating foreach to get to the elements of the array I want. Again, I've read Avoid multiple foreach loops but cannot apply this to my array.

I am using PHP 7.x.

• Zoe Edwards: Tricky thing about arrays is that they’re not designed for this. You might be better off building this as an object that is more useful. If you just need 522 deleted and you don’t mind where, you could build a recursive loop for each array within the array.
• Andy: What do you mean by "they're not designed for this"? I thought storing multiple values in a multi-dimensional array is exactly one of the main uses of arrays in PHP (and possibly other languages)?
• Zoe Edwards: Sort of. Arrays aren’t very useful when you’re looking for values in the array. For example the framework Laravel uses a class called a Collection to be able to go to town on something that’s array like (laravel.com/docs/5.6/collections#available-methods) which might be worth looking at in your framework. I don’t know the context of what you’re doing, but if the filters were a class that you could ‘add’ and ‘remove’ from, that might be easier to manage.
• Andy: Thank you. The context is that it's a web application where a user can "find" and "exclude" filters. This array stores the filters in a session array variable ($arr is a shortened version of the actual name). Here the user is trying to remove a filter. So my plan was to make an ajax call to a script which would then remove the filter by the value - which would be done by removing any instances of the array value from $arr. It's stored in the session because it needs to persist between page re-loads.

Answer 1

foreach() made copy of elements. Then unseting the key is not enough, because you are destroying a local variable.

You could use references & in your foreach() loops and unset like :

 foreach ($arr as &$filters) {
 foreach ($filters as &$filter) {
 foreach ($filter as &$single_filter) {
 foreach ($single_filter as $key => $value) {
 if ($value == $remove) {
 unset($single_filter[$key]);
 }
 }
 }
 }
 }

Or using keys ($k1, $k2, ...) :

 foreach ($arr as $k1 => $filters) {
 foreach ($filters as $k2 => $filter) {
 foreach ($filter as $k3 => $single_filter) {
 foreach ($single_filter as $key => $value) {
 if ($value == $remove) {
 unset($arr[$k1][$k2][$k3][$key]);
 }
 }
 }
 }
 }

• Andy: This is interesting - thank you. Do I have to use multiple foreach statements or is there a way to write it in a shorter way? When I was looking at my code it just looked very repetitive so wasn't sure if I was being "inefficient"?
• Syscall: @Andy Maybe array_search() could be a more efficient way to get the key for a searched value. At least for the last loop.

Answer 2

You could also write a recursive function, so you don't have to use nested foreach:

function deleteRecursive(&$array, &$value) {
 foreach($array as $key => &$subArray) {
 if(is_array($subArray)) {
 deleteRecursive($subArray, $value);
 } elseif($subArray == $value) {
 unset($array[$key]);
 }
 }
}
$valueToDelete = 522;
deleteRecursive($array, $valueToDelete);

Answer 3

function recursiveRemoval(&$array, $val)
{
 if(is_array($array))
 {
 foreach($array as $key=>&$arrayElement)
 {
 if(is_array($arrayElement))
 {
 recursiveRemoval($arrayElement, $val);
 }
 else
 {
 if($arrayElement == $val)
 {
 unset($array[$key]);
 }
 }
 }
 }
}

Call function

recursiveRemoval($array, $value);