Sort a multidimensional array by its second level keys descending, then third level keys (month names) by calendar order

Question

I have a load of folders and I use DirectoryIterator to get them into a multidimensional array. The outcome of this is something like this

array:10 [▼
  "SomeTitle" => array:2 [▼
    2018 => array:3 [▼
      "February" => array:4 [▶]
      "January" => array:1 [▶]
      "March" => array:1 [▶]
    ]
    2017 => array:11 [▼
      "February" => array:9 [▶]
      "January" => array:12 [▶]
      "March" => array:9 [▶]
      "September" => array:9 [▶]
      "June" => array:8 [▶]
      "December" => array:12 [▶]
      "October" => array:8 [▶]
      "July" => array:10 [▶]
      "April" => array:8 [▶]
      "August" => array:10 [▶]
      "May" => array:10 [▶]
    ]
  ]
]

So I have the main key, followed by year, then month, and then some other data.

What I am trying to do is organise the data by year and month. So 2018 should always be first. I then need the months to be organised in month order. At the moment, I am passing the array to this function

function sortArray($arr) {
    ksort($arr);

    foreach ($arr as $k => $v) {
        if (is_array($v)) {
            $arr[$k] = $this->sortArray($v);
        }
    }
    return $arr;
}

I dont think I need the ksort as this seems to put 2017 first. When I run the above, I get the following

array:10 [▼
  "SomeTitle" => array:2 [▼
    2017 => array:11 [▼
      "April" => array:8 [▶]
      "August" => array:10 [▶]
      "December" => array:12 [▶]
      "February" => array:9 [▶]
      "January" => array:12 [▶]
      "July" => array:10 [▶]
      "June" => array:8 [▶]
      "March" => array:9 [▶]
      "May" => array:10 [▶]
      "October" => array:8 [▶]
      "September" => array:9 [▶]
    ]
    2018 => array:3 [▼
      "February" => array:4 [▶]
      "January" => array:1 [▶]
      "March" => array:1 [▶]
    ]
  ]
]

So everything is basically in alphabetical order. Is there any way to change this so the year starts with newest to oldest, and the months are in calendar order?

Answer 1

You can use uksort() to check manually:

• if the keys is a numeric value: sort naturally
• if the keys doesn't match with strtotime() sort with strcmp() (It could be better to check if the key is equal to a "predefined" month name instead of checking strtotime() === false.)
• else sort using strtotime()

Code:

function sortArray($arr) {
    uksort($arr, function($k1, $k2) {
        if (is_numeric($k1)) return $k1-$k2 ;
        if (strtotime($k1) === false) return strcmp($k1, $k2);
        return strtotime($k1) - strtotime($k2);
    });

    foreach ($arr as $k => $v) {
        if (is_array($v)) {
            $arr[$k] = $this->sortArray($v);
        }
    }
    return $arr;
}
$array = sortArray($array);
print_r($array);

Outputs:

Array (
  [SomeTitle] => Array (
    [2017] => Array (
      [January] => Array()
      [February] => Array()
      [March] => Array()
      [April] => Array()
      [May] => Array()
      [June] => Array()
      [July] => Array()
      [August] => Array()
      [September] => Array()
      [October] => Array()
      [December] => Array()
    )
    [2018] => Array (
      [January] => Array()
      [February] => Array()
      [March] => Array()
    )
  )
)

Here is a working demonstration.