getIn.php

<?php

function getIn($obj, $keys, $default = null) {
  $key = $keys[0];
  $rest = array_slice($keys, 1);
  if ($obj instanceof StdClass) {
    if (isset($obj->{$key})) {
      if (count($rest) > 0) {
        return getIn($obj->{$key}, $rest);
      } else {
        return $obj->{$key};
      }
    }
  } else if (is_array($obj)) {
    if (isset($obj[$key])) {
      if (count($rest) > 0) {
        return getIn($obj[$key], $rest);
      } else {
        return $obj[$key];
      }
    }
  }
  return $default;
}

$x = (object) ['a' => [10]];
echo json_encode(getIn($x, ['a', '0']));

removeIn.php

<?php

function removeIn($obj, $keys, $default = null) {
  $key = $keys[0];
  $rest = array_slice($keys, 1);
  if ($obj instanceof StdClass) {
    if (isset($obj->{$key})) {
      if (count($rest) > 0) {
        $obj->{$key} = removeIn($obj->{$key}, $rest);
      } else {
        unset($obj->{$key});
      }
    }
  } else if (is_array($obj)) {
    if (isset($obj[$key])) {
      if (count($rest) > 0) {
        $obj[$key] = removeIn($obj[$key], $rest);
      } else {
        unset($obj[$key]);
      }
    }
  }
  return $obj;
}

$x = (object) ['a' => [10]];
echo json_encode(removeIn($x, ['a', 0]));