python - 根据特定字段对字符串列表进行排序

Question

概述:我有这样的数据(每一行都是一个字符串):

81:0A:D7:19:25:7B, 2016-07-14 14:29:13, 2016-07-14 14:29:15, -69, 22:22:22:22:22:23,null,^M3B:3F:B9:0A:83:E6, 2016-07-14 01:28:59, 2016-07-14 01:29:01, -36, 33:33:33:33:33:31,null,^MB3:C0:6E:77:E5:31, 2016-07-14 08:26:45, 2016-07-14 08:26:47, -65, 33:33:33:33:33:32,null,^M61:01:55:16:B5:52, 2016-07-14 06:25:32, 2016-07-14 06:25:34, -56, 33:33:33:33:33:33,null,^M

我想根据每个字符串中出现的第一个时间戳对每一行进行排序，这四个记录是:

2016-07-14 01:28:59

2016-07-14 06:25:32

2016-07-14 08:26:45

2016-07-14 14:29:13

现在我知道了 sort() 方法，但我不明白如何使用这里根据这个(时间戳)数量对所有行进行排序，我确实需要保留最终的以与其他服务将要使用的格式相同的格式对数据进行排序。

我也知道我可以制作 key() 但我不清楚如何制作它以在时间戳字段上进行排序。

Answer 1

您可以使用就地排序的列表方法 list.sort 或使用返回新列表的 sorted() 内置函数。 key 参数采用一个函数，它在排序之前应用于序列的每个元素。您可以结合使用 string.split(',') 和对第二个元素的索引，例如some_list[1]，所以:

In [8]: list_of_strings
Out[8]: 
['81:0A:D7:19:25:7B, 2016-07-14 14:29:13, 2016-07-14 14:29:15, -69, 22:22:22:22:22:23,null,^M',
 '3B:3F:B9:0A:83:E6, 2016-07-14 01:28:59, 2016-07-14 01:29:01, -36, 33:33:33:33:33:31,null,^M',
 'B3:C0:6E:77:E5:31, 2016-07-14 08:26:45, 2016-07-14 08:26:47, -65, 33:33:33:33:33:32,null,^M',
 '61:01:55:16:B5:52, 2016-07-14 06:25:32, 2016-07-14 06:25:34, -56, 33:33:33:33:33:33,null,^M']

In [9]: sorted(list_of_strings, key=lambda s: s.split(',')[1])
Out[9]: 
['3B:3F:B9:0A:83:E6, 2016-07-14 01:28:59, 2016-07-14 01:29:01, -36, 33:33:33:33:33:31,null,^M',
 '61:01:55:16:B5:52, 2016-07-14 06:25:32, 2016-07-14 06:25:34, -56, 33:33:33:33:33:33,null,^M',
 'B3:C0:6E:77:E5:31, 2016-07-14 08:26:45, 2016-07-14 08:26:47, -65, 33:33:33:33:33:32,null,^M',
 '81:0A:D7:19:25:7B, 2016-07-14 14:29:13, 2016-07-14 14:29:15, -69, 22:22:22:22:22:23,null,^M']

或者，如果您更愿意就地对列表进行排序，

list_of_strings
Out[12]: 
['81:0A:D7:19:25:7B, 2016-07-14 14:29:13, 2016-07-14 14:29:15, -69, 22:22:22:22:22:23,null,^M',
 '3B:3F:B9:0A:83:E6, 2016-07-14 01:28:59, 2016-07-14 01:29:01, -36, 33:33:33:33:33:31,null,^M',
 'B3:C0:6E:77:E5:31, 2016-07-14 08:26:45, 2016-07-14 08:26:47, -65, 33:33:33:33:33:32,null,^M',
 '61:01:55:16:B5:52, 2016-07-14 06:25:32, 2016-07-14 06:25:34, -56, 33:33:33:33:33:33,null,^M']

list_of_strings.sort(key=lambda s: s.split(',')[1])

list_of_strings
Out[14]: 
['3B:3F:B9:0A:83:E6, 2016-07-14 01:28:59, 2016-07-14 01:29:01, -36, 33:33:33:33:33:31,null,^M',
 '61:01:55:16:B5:52, 2016-07-14 06:25:32, 2016-07-14 06:25:34, -56, 33:33:33:33:33:33,null,^M',
 'B3:C0:6E:77:E5:31, 2016-07-14 08:26:45, 2016-07-14 08:26:47, -65, 33:33:33:33:33:32,null,^M',
 '81:0A:D7:19:25:7B, 2016-07-14 14:29:13, 2016-07-14 14:29:15, -69, 22:22:22:22:22:23,null,^M']