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PHP array of subset order

So, I have two arrays.

One is the larger data bit:

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

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

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

Now, my question is: how to get the first array in such a way that the keys of the first array, which have the corresponding keys in the second array, will be displayed first and in the same order as the second array?

So, like this:

 Array ( [36] => foo [90] => bar [12] => blah [58] => blah [60] => blah [72] => blah )
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4 answers
 $array1 = array(12 => 1, 36 => 2, 58 => 3, 60 => 4, 72 => 5); $array2 = array(36 => 1, 60 => 2, 12 => 1); # obtaining keys in the order of question $result = array_intersect_key($array2, $array1); # assign values from original $array1 foreach($result as $key => &$value) { $value = $array1[$key]; } unset($value); # kill reference for safety # add missing elements from $array1 $result += $array1; var_dump($result);

Output:

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

See Array operators for + for arrays.

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A simple solution is O (n).

 $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) }
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use uksort

edit: fixed syntax / logic errors marked little. thanks.

 $array_to_sort = array ( 12 => "blah", 36 => "foo", 58 => "blah", 60 => "blah", 72 => "blah", 90 => "bar" ); $sorted_array = array( 36 => "foo data", 90 => "bar data", 12 => "blah data" ); global $sorted_array_keys; $sorted_array_keys = array_keys($sorted_array); function cmp($a, $b) { global $sorted_array_keys; $a_in_array = in_array($a, $sorted_array_keys); $b_in_array = in_array($b, $sorted_array_keys); if ($a_in_array && $b_in_array) { return array_search($a, $sorted_array_keys) - array_search($b, $sorted_array_keys); } else if ( $a_in_array ) { return -1; } else { return 1; } } uksort ( $array_to_sort , cmp ); print_r($array_to_sort);

It started off nicely and cleanly, but turned out to be pretty ugly and obscure. Now I'm leaning towards some other answers, not mine.

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Here is an example of using uksort with closure, it should be more efficient on a large array, I think, but I haven’t done any benchmark, so ... it's hard to really check without a 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 cannot use closure (php <5.3), you can do something similar using global, but it doesn't get cleared at all.

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