问题描述
---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);