PHP sort array by subset

Question

I have two arrays.

One is a larger bit of data:

Array
(
    [12] => blah
    [36] => foo
    [58] => blah
    [60] => blah
    [72] => blah
    [90] => bar
)

The other is a smaller subset of different but related data in a different order, with each key corresponding to the same key in the larger array:

Array
(
    [36] => foo data
    [90] => bar data
    [12] => blah data
)

Now, my question is, how do I get the first array to be in such an order so that the keys in the first array that have corresponding keys in the second array will appear first and in the same order as the second array?

Thus, like this:

Array
(
    [36] => foo
    [90] => bar
    [12] => blah
    [58] => blah
    [60] => blah
    [72] => blah
)

Answer 1

Simple O(n) solution.

$arr1 = array(12 => 1, 36 => 2, 58 => 3, 60 => 4, 72 => 5);
$arr2 = array(36 => 1, 60 => 2, 12 => 1);

$result = array();

foreach($arr2 as $key => $value) {
    $result[$key] = $arr1[$key];
    unset($arr1[$key]);
}

foreach($arr1 as $key => $value) {
    $result[$key] = $arr1[$key];
}

var_dump($result);

Output:

array(5) {
  [36]=>
  int(2)
  [60]=>
  int(4)
  [12]=>
  int(1)
  [58]=>
  int(3)
  [72]=>
  int(5)
}

Answer 2

Here's an example using uksort with closure, it should be more effective on big array i think, but i haven't done any benchmark so... difficult to really confirm w/o test.

$a = array(
    12 => 'blah'
    ,36 => 'foo'
    ,58 => 'blah'
    ,60 => 'blah'
    ,72 => 'blah'
    ,90 => 'bar'
);

$b = array(
    36 => 'foo data'
    ,90 => 'bar data'
    ,12 => 'blah data'
);

$keysPosition = array_flip(array_keys($b));
uksort($a,function($a,$b) use ($keysPosition){
    if(isset($keysPosition[$a],$keysPosition[$b])){
        return $keysPosition[$a]>$keysPosition[$b]?1:-1;
    }else if( isset($keysPosition[$a]) ){
        return -1;
    }else if( isset($keysPosition[$b]) ){
        return 1;
    }
    return 0;
});

print_r($a);

result:

Array
(
    [36] => foo
    [90] => bar
    [12] => blah
    [72] => blah
    [58] => blah
    [60] => blah
)

If you can't use closure (php <5.3) you can do something similar using a global but it's not clean at all.