Sort an array based on order of another array

Question

I have two arrays:

$arr_a = ['A', 'F', 'C', 'D', 'E', 'B'];
$arr_b = ['D', 'A', 'F'];

, and I need an array with values of $arr_b that is sorted by $arr_a, like this:

array(3) {[0]=>string(1) "A", [1]=>string(1) "F", [2]=>string(1) "D"}

What would be the best way to do it?

PS. All the entries in $arr_b are present in $arr_a, and there is no double entries in $arr_b, and the keys in resultin array are irrelevant, really.

Have you tried any ways so far? You can iterate over $arr_a, checking against $arr_b, and creating a newly formatted $arr_c- but I'm sure theres a better way to do this with a sort function, so I'll leave this in the comments. — Mikel Bitson
– Mikel Bitson, Commented Dec 3, 2015 at 16:15
What if $arr_b contains more items or items that are not in $arr_a? — AbraCadaver
– AbraCadaver, Commented Dec 3, 2015 at 16:16
All the values of $arr_b are always in $arr_a, no need to take that in account. Also the keys in resulting array are irrelevant, really. And $arr_b is done with array_unique, so no double entries. I've tried iterating the array, making new one and then multisorting, but there must be a reasonable way, too? :) — Konservin
– Konservin, Commented Dec 3, 2015 at 16:18

AbraCadaver · Accepted Answer · 2015-12-03 16:21:40Z

3

Probably not a job for sorting. array_intersect() will return items in $arr_a that are in $arr_b in the order that they are in $arr_a:

$arr_b = array_intersect($arr_a, $arr_b);

If you need to re-index then just use array_values() afterward.

answered Dec 3, 2015 at 16:19

AbraCadaver

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2 Comments

Damn. Blew my answer out of the water :D +1

Damn me too :) Simple and whatnot else. No reason not to accept it as an answer. Cheers!

Christian · Accepted Answer · 2015-12-03 16:19:51Z

2

This is what I think you want but your question is not too clear.

$result = array_filter($arr_a, function($item) use($arr_b){
    return in_array($item, $arr_b);
});

Which results in

array(3) {
    [0] = string(1) "A"
    [1] = string(1) "F"
    [3] = string(1) "D"
}

answered Dec 3, 2015 at 16:19

Christian

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does the job exactly how it should, thank you very much. Still Abracadever's seems shorter and a little cleverer.