PHP:按值对对象数组进行分组的函数

class Person {
    public $name;
    public $age;
    
    public function __construct($name, $age) {
        $this->name = $name;
        $this->age = $age;
    }
}

$people = [
    new Person('Alice', 25),
    new Person('Bob', 30),
    new Person('Charlie', 25),
    new Person('Dave', 30),
];

$groupedPeople = array_reduce($people, function($carry, $person) {
    $age = $person->age;
    if (!isset($carry[$age])) {
        $carry[$age] = [];
    }
    $carry[$age][] = $person;
    return $carry;
}, []);

print_r($groupedPeople);

Array
(
    [25] => Array
        (
            [0] => Person Object
                (
                    [name] => Alice
                    [age] => 25
                )

            [1] => Person Object
                (
                    [name] => Charlie
                    [age] => 25
                )

        )

    [30] => Array
        (
            [0] => Person Object
                (
                    [name] => Bob
                    [age] => 30
                )

            [1] => Person Object
                (
                    [name] => Dave
                    [age] => 30
                )

        )

)