计算对象数组中的项目

Question

我有一系列像这样的车.

Array
(
    [2] => Car Object
        (
            [userId] => 3
            [value] => 0
        )
    [58] => Car Object
        (
            [userId] => 2
            [value] => 0
        )
    [64] => Car Object
        (
            [userId] => 2
            [value] => 0
        )

)

我遍历一组用户,并希望知道每个userId出现在cars数组中的次数.数组键是动态数字.每次循环通过用户阵列时,是否需要遍历cars数组？好像很多循环,我怀疑有更好的解决方案:)

提前致谢

更新:我实际上只是想出了一个似乎有用的解决方案.可能不漂亮.评论表示赞赏

$countArray = array();

foreach($cars as $car) {

    if(!$countArray[$car->userId()]) $countArray[$car->userId()] == 0;

    $countArray[$car->userId()]++;
}

print_r($ countArray)给了我

Array ( [94] => 33 [84] => 15 [88] => 53 [80] => 69 [83] => 14 [93] => 3 [76] => 69 [86] => 51 [82] => 77 [87] => 20 [112] => 12 [115] => 16 [114] => 10 [113] => 2 [77] => 1 )

这似乎是正确的

Answer 1

array_count_values( array_map(function($v) { return $v->userId; }, $array) );

结果

Array
(
    [3] => 1
    [2] => 2
)