在PHP中按时间排序数组的问题 [英] questions on sort array by time in php
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
)
)
我上面有一个数组,想按时间对该数组排序.然后,我使用如下代码对结果进行排序,结果是正确的.但是,如果我将代码time[$key] = $val[0]
更改为$time = $val[0]
,则结果是错误的.
I have an array at above and would like to sort this array by time. Then I used the code as following to sort and result is correct. However, if I changed the code time[$key] = $val[0]
to $time = $val[0]
, the result is wrong.
有人可以向我解释吗?非常感谢!
Is there anyone can explain this to me? Many thanks!
foreach($points as $key=>$val){
$time[$key] = $val[0];
array_multisort($time, SORT_ASC, $points);
}
推荐答案
array_multisort
一次排序多个数组.但是,它适用于列数组,因此需要foreach
循环才能获得一列时间.建立此列表后,您可以执行多重排序.根据文档中的此示例,根据$times
中的索引对$points
数组进行排序.
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 $times
, as per this example in the docs.
但是,您无需在foreach
内部执行排序,因为这意味着排序发生了4次(在您的示例中).它只需要发生一次:
However, you don't need to perform the sort inside the foreach
, as that means the sort happens 4 times (in your example). It only needs to happen once:
foreach ($points as $key => $val) {
$time[$key] = $val[0];
}
array_multisort($time, SORT_ASC, $points);
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