CODEWITHSUNDEEP
phparraysmultidimensional-array
Erdem Olcay
Erdem Olcay

Reputation: 427

PHP: Find the exact position of a key in a multidimensional array

I have a dynamic multidimensional array with unique keys in all dimensions. (Array keys can be anything, below array is just an example to show that all keys are unique.)

$data = array(
'0' => array(
    '0-0' => array(
        '0-0-0' => array(
            '0-0-0-0' => 'some value',
            '0-0-0-1' => 'some value',
            ),
        '0-0-1' => array(
            '0-0-1-0' => 'some value',
            '0-0-1-1' => 'some value',
            '0-0-1-2' => 'some value',
            ),
        '0-0-2' => array(
            '0-0-2-0' => 'some value',
            '0-0-2-1' => 'some value',
            ),
        '0-0-3' => array(
            '0-0-3-0' => 'some value',
            ),
        ),
    '0-1' => array(
        '0-1-0' => array(
            '0-1-0-0' => 'some value',
            '0-1-0-1' => 'some value',
            ),
        '0-1-1' => array(
            '0-1-1-0' => 'some value',
            '0-1-1-1' => 'some value',
            ),
        '0-1-2' => array(
            '0-1-2-0' => 'some value',
            '0-1-2-1' => 'some value',
            ),
        ),
    ),
'1' => 'some value',
'2' => array(
    '2-0' => 'some value',
    '2-1' => array(
        '2-1-0' => 'some value',
        ),
    ),
);

Depth and count of sub-arrays are dynamic. All keys are unique, but they don't have a pattern as the above example.

I need to find the exact position (with all parents hierarchically) of a given key in this array. For example;

get_key_position('0-1-2-1', $data); should return array('0', '0-1', '0-1-2', '0-1-2-1') get_key_position('2-1-0', $data); should return array('2', '2-1', '2-1-0') get_key_position('1', $data); should return array('1')

Upvotes: 2

Views: 423

Answers (1)

cFreed
cFreed

Reputation: 4474

I didn't make the effort to go and look at the different links cited by comments under your question, so maybe I'm re-inventing the wheel :)

Anyway, this seems to work in any situation:

function look4key($key, $data, $path = []) {
  if (is_array($data)) {
    foreach ($data AS $localKey => $value) {
      $localKey = (string)$localKey;
      $localPath = array_merge($path, [$localKey]);
      if ($localKey == $key) {
        return $localPath;
      }
      if ($nestedPath = look4key($key, $value, $localPath)) {
        return $nestedPath;
      }
    }
  }
  # returns NULL if $key not found
}

Hope it's rather self-explanatory, except this pitfall: (string)$localKey is needed for keys like '0', '1', etc, because of this automatic cast (look at php manual):

Strings containing valid integers will be cast to the integer type. E.g. the key "8" will actually be stored under 8.

Upvotes: 1

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