CODEWITHSUNDEEP
phpsorting
John Smith
John Smith

Reputation: 6207

Php, usort() fails when I want to order in order

lets have an initial array:

$hits = [
    ['date' => new \DateTime('2019-01-02 12:00:00'), 'roundIndex' => 1],
    ['date' => new \DateTime('2019-01-02 12:00:00'), 'roundIndex' => 4],
    ['date' => new \DateTime('2019-01-02 12:00:00'), 'roundIndex' => 2],
    ['date' => new \DateTime('2019-01-02 12:00:00'), 'roundIndex' => 1],
    ['date' => new \DateTime('2019-01-01 12:00:00'), 'roundIndex' => 1],
    ['date' => new \DateTime('2019-01-04 12:00:00'), 'roundIndex' => 4],
    ['date' => new \DateTime('2019-01-02 12:00:00'), 'roundIndex' => 2],
    ['date' => new \DateTime('2019-01-23 12:00:00'), 'roundIndex' => 1],
    ['date' => new \DateTime('2019-01-22 12:00:00'), 'roundIndex' => 6],
    ['date' => new \DateTime('2019-01-01 12:00:00'), 'roundIndex' => 3],
    ['date' => new \DateTime('2019-01-06 12:00:00'), 'roundIndex' => 2],
    ['date' => new \DateTime('2019-01-28 12:00:00'), 'roundIndex' => 7],
    ['date' => new \DateTime('2019-01-26 12:00:00'), 'roundIndex' => 3],
    ['date' => new \DateTime('2019-01-27 12:00:00'), 'roundIndex' => 5],
    ['date' => new \DateTime('2019-01-26 12:00:00'), 'roundIndex' => 2],
    ['date' => new \DateTime('2019-01-11 12:00:00'), 'roundIndex' => 4],
    ['date' => new \DateTime('2019-01-24 12:00:00'), 'roundIndex' => 3],
    ['date' => new \DateTime('2019-01-08 12:00:00'), 'roundIndex' => 7],
    ['date' => new \DateTime('2019-01-11 12:00:00'), 'roundIndex' => 8],
    ['date' => new \DateTime('2019-01-14 12:00:00'), 'roundIndex' => 6],
    ['date' => new \DateTime('2019-01-13 12:00:00'), 'roundIndex' => 4],
    ['date' => new \DateTime('2019-01-13 12:00:00'), 'roundIndex' => 5],
    ['date' => new \DateTime('2019-01-24 12:00:00'), 'roundIndex' => 2],
    ['date' => new \DateTime('2019-01-27 12:00:00'), 'roundIndex' => 4],
];

I want to order it by date, and if dates are equal, order by roundIndex. Take into account that "roundIndex" might not exists.

First:

usort($hits, static function(array $item1, array $item2) {
    return $item1['date'] < $item2['date'] ? -1 : 1;
});

the result is:

2019-01-01 12:00:00 1
2019-01-01 12:00:00 3
2019-01-02 12:00:00 4
2019-01-02 12:00:00 2
2019-01-02 12:00:00 1
2019-01-02 12:00:00 2
2019-01-02 12:00:00 1
2019-01-04 12:00:00 4
2019-01-06 12:00:00 2
2019-01-08 12:00:00 7
2019-01-11 12:00:00 8
2019-01-11 12:00:00 4
2019-01-13 12:00:00 5
2019-01-13 12:00:00 4
2019-01-14 12:00:00 6
2019-01-22 12:00:00 6
2019-01-23 12:00:00 1
2019-01-24 12:00:00 3
2019-01-24 12:00:00 2
2019-01-26 12:00:00 2
2019-01-26 12:00:00 3
2019-01-27 12:00:00 4
2019-01-27 12:00:00 5
2019-01-28 12:00:00 7

so far so good. So the 2nd sorting:

usort($hits, function($a,$b) use ($defaults) {
    if (
            $a['date']->format('Y-m-d H:i:s') === $b['date']->format('Y-m-d H:i:s'))
        {
            if ($a['roundIndex'] > $b['roundIndex'])
            {
                return 1;
            }
            else
            {
                return -1;
            }
        }
        return 0;
    });

the result is now a bit screwed up:

2019-01-08 12:00:00 7
2019-01-04 12:00:00 4
2019-01-06 12:00:00 2
2019-01-02 12:00:00 1
2019-01-02 12:00:00 1
2019-01-02 12:00:00 2
2019-01-02 12:00:00 2
2019-01-02 12:00:00 4
2019-01-11 12:00:00 4
2019-01-11 12:00:00 8
2019-01-27 12:00:00 4
2019-01-26 12:00:00 3
2019-01-24 12:00:00 2
2019-01-26 12:00:00 2
2019-01-23 12:00:00 1
2019-01-24 12:00:00 3
2019-01-22 12:00:00 6
2019-01-14 12:00:00 6
2019-01-13 12:00:00 4
2019-01-13 12:00:00 5
2019-01-01 12:00:00 3
2019-01-27 12:00:00 5
2019-01-28 12:00:00 7
2019-01-01 12:00:00 1

I dont really understand, why. But if I manually order:

$sizeOfHits = sizeof($hits);
for($i = 0; $i < $sizeOfHits; $i++)
{
    for($j = $i+1; $j < $sizeOfHits; $j++)
    {
        if (
            $hits[$i]['date']->format('Y-m-d H:i:s') === $hits[$j]['date']->format('Y-m-d H:i:s'))
        {
            if ($hits[$i]['roundIndex'] > $hits[$j]['roundIndex'])
            {
                $x = $hits[$j];
                $hits[$j] = $hits[$i];
                $hits[$i] = $x;
            }
        }
    }
}

ALL the result is perfect! But there will be 10000 elements, and it was measured that by ordering manually, it takes 20-30 seconds...

here you can try this out: https://ideone.com/ZaV5Ar

Upvotes: 0

Views: 91

Answers (2)

Nigel Ren
Nigel Ren

Reputation: 57131

Excuse the extremely terse solution, but it basically compares the dates using the spaceship operator (<=>) and if the result of comparing the dates is false (i.e. they are equal) then it returns the comparison of the roundIndex values...

usort($hits, function($a,$b) {
    return $a['date'] <=> $b['date'] ?: 
         ($a['roundIndex']??0) <=> ($b['roundIndex']??0);
});

Upvotes: 1

u_mulder
u_mulder

Reputation: 54831

I suppose this is enough:

usort($hits, function($a, $b) {
   // You can compare DateTime objects directly
   if ($a['date'] == $b['date']) {
       // use ?? to check if `roundIndex` exists
       return ($a['roundIndex'] ?? 0) - ($b['roundIndex'] ?? 0);
   } 
   return $a['date'] > $b['date'];
});

Upvotes: 1

Related Questions