php中按时间排序数组的问题

2021-12-21 00:00:00 multidimensional-array sorting php

---数组 $points---- 

Array
    (
        [0] => Array
            (
                [0] => 2011-10-02 05:30:00
                [1] => 20
            )

        [1] => Array
            (
                [0] => 2011-10-04 09:30:00
                [1] => 12
            )

        [2] => Array
            (
                [0] => 2011-10-01 13:30:00
                [1] => 25
            )

        [3] => Array
            (
                [0] => 2011-10-03 02:30:00
                [1] => 31
            )

    )

我在上面有一个数组，想按时间对这个数组进行排序.然后我使用以下代码进行排序并且结果是正确的.但是，如果我将代码time[$key] = $val[0] 改为$time = $val[0]，结果是错误的.

I have an array at above and would like to sort this array by time. Then I used the code as following to sort and result is correct. However, if I changed the code time[$key] = $val[0] to $time = $val[0], the result is wrong.

有没有人可以向我解释一下?非常感谢！

Is there anyone can explain this to me? Many thanks!

foreach($points as $key=>$val){

        $time[$key] = $val[0];

        array_multisort($time, SORT_ASC, $points);
    }

推荐答案

array_multisort 一次对多个数组进行排序.但是，它适用于列数组，因此需要 foreach 循环来获取时间列.建立此列表后，您可以执行多重排序.$points 数组根据 $times 中的索引进行排序，按照 文档中的这个例子.

array_multisort sorts more than one array at once. However, it works on an array of columns, so the foreach loop is needed to get a column of the times. After building up this list, you can then perform the multisort. The $points array is ordered according to the indices in $times, as per this example in the docs.

但是，您不需要在 foreach 中执行排序，因为这意味着排序发生了 4 次(在您的示例中).它只需要发生一次:

However, you don't need to perform the sort inside the foreach, as that means the sort happens 4 times (in your example). It only needs to happen once:

foreach ($points as $key => $val) {
    $time[$key] = $val[0];
}

array_multisort($time, SORT_ASC, $points);

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