Question

Lets say I have the following data:

$data = array('av','ds','tg','ik','pk','np','rq');

I’m having trouble finding out what tools to use to get the range of strings between two variables.

function sortrange ( $a, $b, $data )
{
    return $range;
}

For example:

sortrange('ds','np', $data);

Would return

array('ds','tg','ik','pk','np');

I would also like it be able to do backwards sorting, for example:

sortrange('np','tg');

Would return:

array('np','pk','ik','tg');

The closest function I found that might be usable was usort, but it couldn’t get anywhere close to what I wanted.

Thanks for any help in advance. 🙂

Answer 1

Note: The following function will just use the first occurance of $start and $end. If they repeat, the behavior may not be what you expect.

function subset_range($array, $start, $end) {
    $start_index = array_search($start, $array);
    $end_index = array_search($end, $array);
    $min = min($start_index, $end_index);
    $max = max($start_index, $end_index);
    $ret = array_slice($array, $min, $max - $min + 1);
    return $start_index < $end_index ? $ret : array_reverse($ret);
}

$data = array('av','ds','tg','ik','pk','np','rq');

print_r(subset_range($data, 'ds', 'np'));
print_r(subset_range($data, 'np', 'tg'));

Output:

Array
(
    [0] => ds
    [1] => tg
    [2] => ik
    [3] => pk
    [4] => np
)
Array
(
    [0] => np
    [1] => pk
    [2] => ik
    [3] => tg
)