php sort associative arrays by keys that those keys exist in other array

Question

I have this array

$myArray=array(

'a'=>array('id'=>1,'text'=>'blabla1'),
'b'=>array('id'=>2,'text'=>'blabla2'),
'c'=>array('id'=>3,'text'=>'blabla3'),
'd'=>array('id'=>4,'text'=>'blabla4'),

);

and i want to sort the above array by the keys a,b,c,d, who exist in another array:

$tempArray=array('c','a','d','b');

How can I do that so the $myArray

looks like this:

$myArray=array(

'c'=>array('id'=>3,'text'=>'blabla3'),
'a'=>array('id'=>1,'text'=>'blabla1'),
'd'=>array('id'=>4,'text'=>'blabla4'),
'b'=>array('id'=>2,'text'=>'blabla2'),

);

thanks for helping me!

I dont know how array_shift can help, but uksort i think can — gadlol
– gadlol, Commented Mar 8, 2013 at 15:24

DaveRandom · Accepted Answer · 2013-03-08 15:28:54Z

3

The simplest and likely most efficient way to do this is by iterating the array that holds the sort order and creating a new, sorted array:

$sorted = array();

foreach ($tempArray as $order) {
  if (isset($myArray[$order])) {
    $sorted[$order] = $myArray[$order];
  }
}

print_r($sorted);

This works because associative arrays implicitly have an order of the order in which elements were added to the array.

See it working

EDIT

Any solution involving a sorting function will likely be much less efficient than this. This is because in order to do it you will need to use a function that takes a callback - this already has an implied overhead of the function call.

The sorting functions also work by comparing items, meaning that the complexity any of those solutions will be greater than that of this solution (the complexity of this is simply O(n)). Also, in order to derive the return value for the sorting function you would need to inspect the target array, finding the position of each of the keys being compared, for each comparison, adding even more complexity.

edited Mar 8, 2013 at 15:28

answered Mar 8, 2013 at 15:20

DaveRandom

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5 Comments

Matt Over a year ago

@MikeB uksort is what he needs

Luc M Over a year ago

@jBaron You should write it in your question ;-)

DaveRandom Over a year ago

@jBaron Any solution involving a sorting function will likely be much less efficient than this. This is because in order to do it you will need to use a function that takes a callback - this already has an implied overhead of the function call. The sorting functions also work by comparing objects, meaning that the complexity any of those solutions will be greater than that of this solution (O(n)). Also, in order to derive the return value for the sorting function you would need to inspect the target array for each comparison, adding even more complexity.

gadlol Over a year ago

For thousand entries you suggest not using uksort?

DaveRandom Over a year ago

@jBaron The more entries you have, the less efficient the sorting functions become, because of the way Quicksort works. This will perform no more operations than the number of elements in $tempArray, whereas the sort functions will perform many more operations for more than just a few elements. Compare this (4 items) with this (5 items). You can see that by adding one more item to the target array, it (probably) adds considerably more than one iteration. The only time it doesn't is when the elements are already in the right order.

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