Recursive array_search?

Question

I have the following array:

(
    [https://i.imgur.com/vyGHgZN.jpg] => dummy2
    [https://i.imgur.com/UYK4Agz.png] => dummy
    [https://i.imgur.com/xEXdKYn.jpg] => dummy
)

Were [key] is the image link and => dummy2 the image location on my site.

Using the following function, I remove all of the links and duplicates.

$unique=array_unique(array_values($img_array));

Which returns the following array:

(
    [0] => dummy2
    [1] => dummy
)

Now, I want to generate the following array:

(
    [dummy]
    (
       [0] => https://i.imgur.com/UYK4Agz.png
       [1] => https://i.imgur.com/xEXdKYn.jpg
    )

    [dummy2]
    (
       [0] => https://i.imgur.com/vyGHgZN.jpg
    )
)

So I use the following function to get the links for each category:

foreach($unique as $value){
    print_r(array_search($value,$img_array));
}

Which returns the following:

https://i.imgur.com/vyGHgZN.jpghttps://i.imgur.com/vyGHgZN.jpg

But as you can see, its missing a link... Looks like array_search isn't recursive!

Tried many, many functions that are, apparently, recursive, but they all return nothing, in my case.

Any ideas?

Answer 1

Just loop the array and make the key value and the value the key:

$arr = array(
    "https://i.imgur.com/vyGHgZN.jpg" => "dummy2",
    "https://i.imgur.com/UYK4Agz.png" => "dummy",
    "https://i.imgur.com/xEXdKYn.jpg" => "dummy"
);

foreach($arr as $key => $val){
    $res[$val][] = $key;
}

var_dump($res);

Output:

array(2) {
  ["dummy2"]=>
  array(1) {
    [0]=>
    string(31) "https://i.imgur.com/vyGHgZN.jpg"
  }
  ["dummy"]=>
  array(2) {
    [0]=>
    string(31) "https://i.imgur.com/UYK4Agz.png"
    [1]=>
    string(31) "https://i.imgur.com/xEXdKYn.jpg"
  }
}

https://3v4l.org/0E9Vm

Answer 2

Simple foreach loop would do,

$result = [];
foreach ($arr as $key => $value) {
    $result[$value][] = $key; // grouping array as per value as key
}
print_r($result);

Demo

Output:-

Array
(
    [dummy2] => Array
        (
            [0] => https://i.imgur.com/vyGHgZN.jpg
        )

    [dummy] => Array
        (
            [0] => https://i.imgur.com/UYK4Agz.png
            [1] => https://i.imgur.com/xEXdKYn.jpg
        )

)