使用条件按值对多维数组进行排序

Question

Sorting a multidimensional array by value is fairly easy and has been answered multiple times already here

usort($myArray, function($a, $b) {
    return $a['field'] - $b['field'];
});

The problem I am having now, is that I need another condition. Let's imagine I have an array with 10 cars and 10 motorcycles. These cars and motorcycles are each an array/object with values containing a field speed. Like

$car1 = [
    'speed' => 100,
    'type' => 'car'
]
$car2 = [
    'speed' => 120,
    'type' => 'car'
]
$car3 = [
    'speed' => 180,
    'type' => 'car'
]
$motorcycle1 = [
    'speed' => 80,
    'type' => 'motorcycle'
]

Those are all stored in one array

$vechicles = [$car1, $car2, $car3, $motorcycle1]

What I now want to do is to sort by speed. Which is, as I said, easy

usort($myArray, function($a, $b) {
        return $a['speed'] - $b['speed'];
});

The problem I am facing now, is, that independent of the speed value, at least every third vehicle MUST be a motorcycle. It can be, that the first entries are motorcycles, doesn't matter, but it can't be all cars. It always have to be at least one motorcycle. Doesn't matter here if it's 1, 2 or 3 motorcycles. So in the end it should look like this

$finalArray = [$car3, $car2, $motorcycle1, $car1];

As you can see, while $car1 is faster than $motorcycle1, the motorcycle comes earlier.

The thing is, when I have two different arrays

$cars = [$car1, $car2, $car3]

and

$motorcycles = [$motorcycle1]

I can simply splice it in, like

array_splice($cars, 2, 0, $motorcycles[0]);

But then I got the problem that I can't sort it by speed. Is there a way to achieve this?

Answer 1

Well, easiest solution

$vehicles = [...]; // sorted by speed already

$count = count($vehicles);
$temp = 0;

foreach($vehicles as $key => $veh){

    if(is_car($veh)){
        $temp++;
    }else{
        $temp = 0;
    }

    if($temp == 3){

        for($i = $key + 1; $i<=$count; $i++){

            if(is_motorcycle($vehicles[$i])){

                array_splice($vehicles, $key, 0, $vehicles[$i]);
                break;

            }

        }
        $temp = 0;

    }

}

Obviously this is not working code, I just wrote it to illustrate my idea, if you think you can benefit from it, happy tweaking! :P