Question

There is function array_values in PHP such that

$array2 = array_values($array1);

$array2 has the same values as $array1 but keys are from
0 to sizeof($array1) - 1. Is it possible to get mapping from old keys to new keys?

EDIT. I will explain on an example:

$array1 = array( 'a' => 'val1', 'b' => 'val1');
$array2 = array_values( $array1 );

so now array2 has next values

$array2[0] = 'val1'
$array2[1] = 'val2'

How get array3 such that:

$array3['a'] = 0
$array3['b'] = 1

Answer 1

To produce a key map you need to first get the keys into a regular array and then flip the keys and values:

$array1_keymap = array_flip(array_keys($array1));

For example:

$array1 = array(
    'a' => 123,
    'b' => 567,
);

$array1_values = array_values($array1);
$array1_keymap = array_flip(array_keys($array1));

Value of $array1_values:

array(
    0 => 123,
    1 => 567,
);

Value of $array1_keymap:

array(
    'a' => 0,
    'b' => 1,
);

So:

$array1['a'] == $array1_values[$array1_keymap['a']];
$array1['b'] == $array1_values[$array1_keymap['b']];