Sorting each level of a nested multidimensional PHP array

Question

I have a multidimensional PHP array that I am using to generate a hierarchical UL tree. However, before displaying the UL tree, I would like to sort each level within the array alphabetically by the 'name' attribute. I am imagining a function that recursively checks each level, organizes it alphabetically, and moves on to the next level to sort that level. But I'm not sure how to do that. Any help would be appreciated!

My array:

Array ( 
 [0] => Array ( 
   [id] => 39348
   [parent] => 0
   [name] => Test 
   [children] => Array ( 
     [0] => Array ( 
       [id] => 41911 
       [parent] => 39348 
       [name] => Test2 
       [children] => Array ( 
         [0] => Array ( 
            [id] => 40929
            [parent] => 41911
            [name] => Test3 
            [children] => Array ( 
               [0] => Array (
                   [id] => 40779 
                   [parent] => 40929 
                   [name] => C 
               ) 
               [1] => Array (
                   [id] => 40780 
                   [parent] => 40929
                   [name] => A
               ) 
            ) 
         )
      ) 
   )

My attempt, which is moving the order around, but it is still not alphabetical. Note, the array($this,'sortByName') is required by CodeIgniter, which I am working in:

function recursive_sort($array) {
  usort($array, array($this,'sortByName'));
  foreach($array as $key => $value) {
    if(isset($value['children']) && !empty($value['children']) && is_array($value['children'])) {
      $array[$key]['children'] = $this->recursive_sort($value['children']);
    }
  }
  return $array;
}

function sortByName($a, $b){
    return $a->name - $b->name;
}

UPDATE: SOLUTION

function recursive_sort($array,$child='children') {
        usort($array,function($a,$b){
            return strcasecmp($a['name'], $b['name']);
        });
        foreach($array as $key => $value) {
            if(isset($value[$child]) && !empty($value[$child]) && is_array($value[$child])) {
              $array[$key][$child] = $this->recursive_sort($value[$child],$child);
            }
        }
        return $array;
    }

Check this if it helps : stackoverflow.com/a/3805256/5645769 — Tᴀʀᴇǫ Mᴀʜᴍᴏᴏᴅ
– Tᴀʀᴇǫ Mᴀʜᴍᴏᴏᴅ, Commented Dec 29, 2015 at 5:49
@TareqMahmood Thank you for the reference. However, the solutions listed for that post only seem to apply to the first level within the multidimensional array. They do not address my situation where I have nested arrays. — skiindude22
– skiindude22, Commented Dec 29, 2015 at 6:43

Austin Derrow-Pinion · Accepted Answer · 2015-12-29 07:19:38Z

2

I typed up a an algorithmic way of thinking so you can implement the code yourself. Besides, I wouldn't want to take away all the fun away from you! :-)

If it isn't enough for you, check out this.

function example(element) {
    if (no children exist) return
    if (only one element exist on this level) 
        // if this code is reached, this element has children
        example(children element)
        return
    names = { array of all name attributes of all elements on this level }
    sort(names)
    [0] => names[0]
    [1] => names[1]
       .. and so on for however many elements there are
    return

answered Dec 29, 2015 at 7:19

Austin Derrow-Pinion

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4 Comments

Austin Derrow-Pinion Over a year ago

@BasheerAhmed what do you even mean by that? You're a confusing person.

skiindude22 Over a year ago

@AustinDerrow-Pinion thank you, I have updated my post with my attempt at recursively sorting, but it isn't working right. Maybe you will have some input!

Austin Derrow-Pinion Over a year ago

@skiindude22 instead of subtracting the names, use strcmp(string1, string2) function. w3schools.com/php/func_string_strcmp.asp

skiindude22 Over a year ago

@AustinDerrow-Pinion strcmp() didn't work, but I did some more research on it, and strcasecmp() wound up doing the trick. Thanks for pointing me in the right direction, it's working now! I have updated my post with the working code.

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