How do I sort 3-level multi-dimensional array with dynamic keys?

Question

I tried implementing a solution for my 3-level multi-dimensional array. The problem arose when I realised I can't use keynames to target a value as they're dynamically created (SKU-style).

A skimmed version of my array data:

Array
(
    ['weeks'] => Array
    (
        [14] => Array
            (
                [some_sku] => 28.5
                [some_sku_1] => 10.8
                [some_sku_2] => 11.21
                [some_sku_3] => 19.98
                [some_sku_4] => 20.79
            )
        [31] => Array
            (
                [some_sku_1] => 28.5
                [some_sku_5] => 10.8
                [some_sku_6] => 11.21
                [some_sku_7] => 19.98
                [some_sku_9] => 20.79
            )
    )
)

I thought maybe I could sort the individual arrays within the "mothership" array but that doesn't seem to achieve what I want:

foreach ($data as $item)
{
    foreach ($item as $el)
    {
        usort($el, function($a, $b){return $a > $b;});
    }
}

But the data remains the same: https://3v4l.org/E6W8Z

My guess is that whilst it may happen it doesn't store the values in the array. I also can't assign the output of usort() as that returns a boolean instead of the sorted array.

How am I able to sort my child arrays within the parent array by value (high - low)?

Florian Richard · Answer 1 · 2019-10-25T14:50:19.067

You can try like this (note uasort instead of usort if you want to keep your index "some_sku_"):

foreach($data as $key1 => $value1)
{
    foreach($value1 as $key2 => $value2)
    {
        uasort($value2, function($a, $b)
        {
            return strcasecmp($a, $b);
        });
        $value1[$key2] = $value2;
    }
    $data[$key1] = $value1;
}

Simplify into this (note the "&" who permit to assigning that array by reference, who permit to work on the original variable directly, also without the "&" the variable is lost, so in this case you need the first solution with "$data[$key]=$val") :

  foreach($data as &$child1)
    {
        foreach($child1 as &$child2)
        {
            uasort($child2, function($a, $b)
            {
                return strcasecmp($a, $b);
            });
        }
    }

Results :

 Array
    (
        [weeks] => Array
            (
                [14] => Array
                    (
                        [some_sku_1] => 10.8
                        [some_sku_2] => 11.21
                        [some_sku_3] => 19.98
                        [some_sku_4] => 20.79
                        [some_sku] => 28.5
                    )

                [31] => Array
                    (
                        [some_sku_5] => 10.8
                        [some_sku_6] => 11.21
                        [some_sku_7] => 19.98
                        [some_sku_9] => 20.79
                        [some_sku_1] => 28.5
                    )
            )
    )

Hey, I actually found a dupe for this that works well - will be closed or removed at some point (sorry!) — treyBake, Oct 25 '19 at 14:48

How do I sort 3-level multi-dimensional array with dynamic keys?

1 Answers1