问题描述
我有一个包含三个元素的列表，格式如下:
I have a list with three elements in the following format:
[('ABC', 'DEF', 2), ('GHI', 'JKL', 6), ('MNO', 'PQR', 22), ('ABC', 'STU', 2)...]
我想按数字对最后一个元素进行排序.然后按字母顺序第一个元素.最后，如果有并列，则通过第二个元素.所以我的输出是:
I would like to sort by last element numerically. Then by first element alphabetically. Lastly by the second element if there is a tie. So my output would be:
[('MNO', 'PQR', 22), ('GHI', 'JKL', 6), ('ABC', 'DEF', 2), ('ABC', 'STU', 2)...]
我尝试过
list_name.sort(reverse=True, key=lambda x: x[2])
这仅按降序排列的最后一个元素排序.如何添加实现按字母顺序对第一和第二个元素进行排序的工具.
This only sorts by the last elements descending. How do I add the implement sorting the first and second element in that order alphabetically.
推荐答案
返回一个元组，并取反数字，而不使用reverse:
Return a tuple, and negate the number instead of using reverse:
list_name.sort(key=lambda x: (-x[2],) + x[:2])
这将返回(-item3, item1, item2)，并且首先按整数item3以降序的顺序进行排序，当绑定到数字时，按item1进行排序(按字母顺序，升序)，然后在item2上.
This returns (-item3, item1, item2) and sorting takes place first by the integer item3 in descending order, when tied on the number sorting is done on item1 (alphabetically, ascending order), then on item2.
实际上，元组按字典顺序排序.
In effect, tuples are sorted in lexicographical order.
演示:
>>> list_name = [('ABC', 'DEF', 2), ('GHI', 'JKL', 6), ('MNO', 'PQR', 22), ('ABC', 'STU', 2)]
>>> list_name.sort(key=lambda x: (-x[2],) + x[:2])
>>> list_name
[('MNO', 'PQR', 22), ('GHI', 'JKL', 6), ('ABC', 'DEF', 2), ('ABC', 'STU', 2)]
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