Sort each subarray of a 2d array by delimited string values

Question

Original array:

$resolutions =  array (
    "Desktop monitor" => array (
        //Standard 4:3
        "800x600" => "800x600",
        "1024x768" => "1024x768",
        "1600x1200" => "1600x1200",
        //Wide 16:10
        "960x600" => "960x600",
        "1280x800" => "1280x800",
        "1440x900" => "1440x900",
        "1680x1050" => "1680x1050",
        "1920x1200" => "1920x1200",
    ),
    "Apple" => array (
        "DeviceX" => "2048x1536",
        "DeviceY" => "1024x768",
    ),
);

Wanted array:

$resolutions =  array (
    "Desktop monitor" => array (
        "800x600" => "800x600",//Standard 4:3
        "960x600" => "960x600",//Wide 16:10
        "1024x768" => "1024x768",//Standard 4:3
        "1280x800" => "1280x800",//Wide 16:10
        "1440x900" => "1440x900",//Wide 16:10
        "1600x1200" => "1600x1200",//Standard 4:3
        "1680x1050" => "1680x1050",//Wide 16:10
        "1920x1200" => "1920x1200",//Wide 16:10
    ),
    "Apple" => array (
        "DeviceY" => "1024x768",
        "DeviceX" => "2048x1536",
    ),
);

What I have tried:

foreach ($resolutions as $screen => $resolution) { 
    foreach($resolution as $key => $val) {
        $newarray[$key] = $row[$val];
    }
    array_multisort($newarray, SORT_DESC, $resolution);
}

I thought that I'm half way to end, but the code above gave me some non sense (for me), ie: first goes resolution 1024x768, then 1280x800, followed by 1440x900 and in the end is 800x600.

Answer 1

The problem is that you are sorting alphabetically. You will need to calculate the size of each resolution to sort them correctly. This will require writing a custom comparison function that calculate the resolution sizes and compare them.

foreach ($resolutions as &$resolution)
    uasort($resolution, function ($a, $b) { return array_product(explode('x', $a)) - array_product(explode('x', $b)); });