sort array with defined key order

sort_array_by_key_weight.php

$arr = [
  'x' => '1',
  'foo' => 'me',
  'y' => '2',
  'bar' => '42',
  'z' => '3',
];

/**
 * sort array with defined key order (undefined keys remain in random order appended)
 * $keys_order ['key name' => weight]
 * from light -> heavy (sinking)
 */
     
$keys_order = [
  'foo' => 1,
  'bar' => 2,
];

uksort(
  $arr,
  fn($a, $b) =>
    (isset($keys_order[$a]) ? $keys_order[$a] : PHP_INT_MAX)
    - (isset($keys_order[$b]) ? $keys_order[$b] : PHP_INT_MAX)
);

/** Result:
Array
(
  [foo] => me
  [bar] => 42
  [x] => 1
  [y] => 2
  [z] => 3
)
 */