Sorting a multi-dimensional array according to length in PHP

Question

I have a function that finds all the possible combinations of an array:

function combination($array) 
{    
    $results = array(array());

    foreach ($array as $element)
        foreach ($results as $combination)
            array_push($results, array_merge(array($element), $combination));

    return $results;
}

This returns a multidimensional array and it works.

If I try to print the array, I use this:

foreach (combination($set)  as $combination)
{
    print join("\t", $combination) . "  - ";
}

For: $set = array('s','f','g');

The output is: - s - f - f s - g - g s - g f - g f s -

Now what I cant figure out is how can I sort the combinations according to length in a way where the output becomes: - g f s - g s - g f - f s - g - s - f -

Have a look at this link... stackoverflow.com/questions/838227/… — Kamall A Joshi
– Kamall A Joshi, Commented Jun 1, 2012 at 15:49

Katai · Accepted Answer · 2012-06-01 15:33:46Z

3

you need to use 'usort' for this:

function sortByLength($a, $b) {
    return count($b) - count($a);
}

$result = combination($set);

usort($result, 'sortByLength');

you could also just use 'sortByLength' as an anonymous function, instead of defining it, if you use this only once:

$result = combination($set);

usort($result, function($a, $b) {
    return count($b) - count($a);
} );

edited Jun 1, 2012 at 15:33

answered Jun 1, 2012 at 15:21

Katai

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6 Comments

Haz Over a year ago

Thats right but Im not trying to sort $set, I am trying to sort combination($set).

Katai Over a year ago

just save the result of combination($set) in a variable - i edited the example for you

Haz Over a year ago

your script works with a 1 dimensional array, combination($set) is a multidimensional array

Katai Over a year ago

can you post the array structure of the multidimensional array? does the sorted array have to stay multidimensional, or one-dimensional?

Katai Over a year ago

for that, you basically only need to change strlen() to count() - it even would stay multidimensional that way. I'll edit it in.

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