PHP按键中值的出现次数排序多维数组

Question

I'm trying to first sort by quantity in Rank and if the quantity is equal then sort numerically by Rank.

It might sound complicated but here is the pseudo-code I envision

1. First sort arrays by the number of repeated values in Rank.
2. If number of repeated values is equal sort numerically by the value in Rank.

I guess its kinda recursive seeing as the 2nd part is performed on all sub-arrays.

I've been trying usort but I can't get it so see the count of repeated rank values in the array. Multisort doesn't seem to fit either.

Example:

Array
(
    [0] => Array
        (
            [Rank] => 7
            [Suit] => Hearts
        )

    [1] => Array
        (
            [Rank] => 3
            [Suit] => Hearts
        )

    [2] => Array
        (
            [Rank] => 6
            [Suit] => Spades
        )

    [3] => Array
        (
            [Rank] => 10
            [Suit] => Spades
        )

    [4] => Array
        (
            [Rank] => 3
            [Suit] => Spades
        )

    [5] => Array
        (
            [Rank] => 6
            [Suit] => Hearts
        )

    [6] => Array
        (
            [Rank] => 2
            [Suit] => Clubs
        )

)

According to my algorithm

Array
(

    [0] => Array
        (
            [Rank] => 6
            [Suit] => Hearts
        )

    [1] => Array
        (
            [Rank] => 6
            [Suit] => Spades
        )

    [2] => Array
        (
            [Rank] => 3
            [Suit] => Spades
        )


    [3] => Array
        (
            [Rank] => 3
            [Suit] => Hearts
        )

    [4] => Array
        (
            [Rank] => 10
            [Suit] => Spades
        )

    [5] => Array
        (
            [Rank] => 7
            [Suit] => Hearts
        )

    [6] => Array
        (
            [Rank] => 2
            [Suit] => Clubs
        )

)

Answer 1

The easiest solution I could come up with, is to use a second array in which we'll store the card count for each rank. We can then pass this array to the sorting function in order to get the result we want.

Here's an example of how this would look:

$cards = [...];

$ranks = [];

// Count the cards for each rank
foreach ($cards as $card) {
    if (!isset($ranks[$card['Rank']])) {
        $ranks[$card['Rank']] = 0;
    }

    $ranks[$card['Rank']]++;
}

// Sort the cards array
usort($cards, function ($a, $b) use ($ranks) {
    // If the cards count is the same for the rank, compare rank
    if ($ranks[$a['Rank']] == $ranks[$b['Rank']]) {
        return $a['Rank'] - $b['Rank'];
    }

    // Compare the card count for the rank
    return $ranks[$a['Rank']] - $ranks[$b['Rank']];
});