PHP sorting a set of multidimensional arrays

Question

I have an array which contains another array with a distance and ID in it. I need to sort the distance part of the array, so the ID remains correlated with it's respective distance.

Eg.

array
(
    [0] => array(
                    [0] => 170
                    [1] => 123abc
    )
    [1] => array(
                    [0] => 150
                    [1] => 456def
    )
)

Now, I want to sort the distances ascending so my sorted output would look like:

array
(
    [0] => array(
                    [0] => 150
                    [1] => 456def
    )
    [1] => array(
                    [0] => 170
                    [1] => 123abc
    )
)

As 150 is smaller than 170, it has 'moved' up.

I've looked at the PHP functions for this; array_multisort() etc. however these only seem to sort the values within the arrays rather than a set of arrays.

Any help appreciated.

EDIT: There isn't a fixed number of items within the first array - it ranges from 1 to infinity.

you can try array_map() that will sort each array inside the parent array . — Prafulla Kumar Sahu
– Prafulla Kumar Sahu, Commented Nov 28, 2015 at 9:52
Why to use array_map if you can simply use usort or uasort — Narendrasingh Sisodia
– Narendrasingh Sisodia, Commented Nov 28, 2015 at 10:17
Sorry, I should have said there can be more then two 'sets' of distance & id values. I don't think using usort in that case would be feasible. — CrabLab
– CrabLab, Commented Nov 28, 2015 at 12:27
@RyanVincent Sorry - yes that does work. I assumed that usort would only work for nested arrays. Paste here: pastebin.com/XwCNPaMN — CrabLab
– CrabLab, Commented Nov 28, 2015 at 13:22

roullie · Accepted Answer · 2015-11-28 09:53:41Z

2

use usort

usort($yourArray, function($a, $b) {
    return $a[0] - $b[0]; // index 0 is your 150 or 170
});

answered Nov 28, 2015 at 9:53

roullie

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