Sort array by keys of another array.

Question

Hello

There are 2 arrays, both with the same length and with the same keys:

$a1 = [1=>2000,65=>1354,103=>1787];
$a2 = [1=>'hello',65=>'hi',103=>'goodevening'];

asort($a1);

The keys of a1 and a2 are id's from a database.

a1 gets sorted by value. Once sorted, how can we use the same sorting order in a2?

Thanks!

Answer 1

You probably want to look at array_multisort() if you can handle losing ID association (arrays will be re-indexed).

array_multisort($a1, $a2);

Answer 2

foreach($a1 as $key => $value){
   //do something with $a2
   echo $a2[$key];
}

Answer 3

I believe this works:

$a1 = array(1=>2000,65=>1354,103=>1787);
$a2 = array(1=>'hello',65=>'hi',103=>'goodevening');

asort($a1); // sort $a1, maintaining array index

// sort $a2 by key, using the order of $a1
function my_uksort($a, $b) {
    global $a1;

    return $a1[$a] < $a1[$b] ? -1 : 1;
}
uksort($a2, 'my_uksort');

var_dump($a1);
var_dump($a2);

Answer 4

Not optimal maybe.. but it's short:

$a1 = array(1=>2000,65=>1354,103=>1787);
$a2 = array(1=>'hello',65=>'hi',103=>'goodevening');
asort($a1);

foreach(array_keys($a1) as $i) $out[$i] = $a2[$i];

echo join("\n", $out);

look into uasort() also