“按x（升序），然后按y（降序）为csv文件在python [英] "sort by x (ascending) then by y (descending)" for a csv file in python
问题描述
所以我有一个csv文件，我想使用2列排序（基本上相同的想法在excel中的按顺序由somecol然后由anothercol）。
So I have a csv file that I want to sort using 2 columns (basically the same idea in excel as "sort by somecol then by anothercol").
鉴于csvbody是从csv文件生成的列表的列表，我现在的方式，我发现从这个问题是 sortedcsv = sorted（csvbody，key = operator.itemgetter（somecol，anothercol））问题是，我想按升序排序，按降序排序。是否有办法做到这一点（更好，在一行）？
Given that csvbody is a list of lists generated from the csv file, the way I have it right now that I found from this question is sortedcsv = sorted(csvbody, key = operator.itemgetter(somecol, anothercol)) The issue is that I want to sort by somecol in ascending order and anothercol in descending order. Is there a way to do this (even better, in one line)?
我知道我可以做 sortedcsv = sorted（csvbody，key = operator.itemgetter（somecol，anothercol），reverse = True）但是它会按降序对它们进行排序。然后我尝试做两行：
I know that I could do sortedcsv = sorted(csvbody, key = operator.itemgetter(somecol, anothercol), reverse = True) but then it sorts both of them in descending order. Then I tried doing two lines:
sort1 = sorted(csvbody, key = operator.itemgetter(somecol))
sort2 = sorted(sort1, key = operator.itemgetter(anothercol), reverse = True))
这不工作，因为第二次排序只是覆盖第一次排序（就好像我进入excel，并按降序排序只是由anothercol）
However this doesn't work because the second sort just overrides the first sort (it's as if I went into excel and sorted in descending order just by "anothercol")
如果你需要我包括更多的信息请让我知道。
If you need me to include more information please let me know.
推荐答案
由于Python的排序是保证稳定，需要：
Since Python's sort is guaranteed to be stable, this should do what you want:
# First sort by secondary key
sortedcsv = sorted(csvbody, key=operator.itemgetter(anothercol, reverse=True)
# Then sort by primary key
sortedcsv = sorted(sortedcsv, key=operator.itemgetter(somecol))
参考：
- https://wiki.python.org/moin/HowTo/Sorting#Sort_Stability_and_Complex_Sorts
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