How to flip elements with numeric key in php?

Question

I've an array in php like bellow:

array:2 [
  "element_a" => array:1 [
    "string" => array:3 [
      "min" => 5
      "max" => 50
      0 => "nullable" // this element need be flipped
    ]
  ]
  "element_b" => array:1 [
    0 => "string" // this need too
  ]
]

And I need flip elements with numeric key value.. I want get the following output:

array:2 [
  "element_a" => array:1 [
    "string" => array:3 [
      "min" => 5
      "max" => 50
      "nullable" => true
    ]
  ]
  "element_b" => array:1 [
    "string" => true
  ]
]

Any ideas about how i can get it?

Thanks.

Edit

I tried this, but no results:

array_walk_recursive($array, function (&$value, &$key) {
    if (is_numeric($key)) {
        list($value, $key) = [$key, $value];
    }
});

Answer 1

This solution will fix your array in place (by reference):

function fix( array &$array ) {
  foreach( $array as $key => &$value ) {
    if( is_array( $value ) ) {
      fix( $value );
    }
    else if( is_numeric( $key ) ) {
      $array[ $value ] = true;
      unset( $array[ $key ] );
    }
  }
}

$yourArray = [
  "element_a" => [
    "string" => [
      "min" => 5,
      "max" => 50,
      0 => "nullable" // this element need be flipped
    ]
  ],
  "element_b" => [
    0 => "string" // this need too
  ]
];

fix( $yourArray );
var_dump( $yourArray );