How to assign new numerical keys to an array and sort based on the original keys?

$arrayOne = array('one','two','three'); //You set an array with certain elements
unset($array[1]);                       //You unset one or more elements.
$arrayTwo = array_values($arrayOnw);    //You reindex the array into a new one.

print_r($arrayTwo);                     //Print for prove.

The print_r results are:

Array ( [0] => one [1] => three )

ksort() will sort by key, then get the values with array_values() and that will create a new array with keys from 0 to n-1.

ksort($array)
$array = array_values( $array );

Of course, you don't need ksort if it's already sorted by key. You might as well use array_values() directly.

If you want to sort the array by key value use ksort():

ksort($array);
print_r($array);

Output:

Array
(
    [3] => apple
    [5] => pear
    [23] => banana
)

That will preserve the keys however. To reassign keys for an array from 0 onwards use array_values() on the result:

ksort($array);
$array_with_new_keys = array_values($array); // sorted by original key order
print_r($array_with_new_keys);

Output:

Array
(
    [0] => apple
    [1] => pear
    [2] => banana
)