问题
I generate a grouped dataframe df = df.groupby(['X','Y']).max() which I then want to write (to csv, without indexes). So I need to convert 'X' and 'Y' back to regular columns; I tried using reset_index(), but the order of columns was wrong.
How to restore columns 'X' and 'Y' to their exact original column position?
Is the solution:
df.reset_index(level=0, inplace=True)
and then find a way to change the order of the columns?
(I also found this approach, for multiindex)
回答1:
This solution keeps the columns as-is and doesn't create indexes, after grouping, hence we don't need reset_index() and column reordering at the end:
df.groupby(['X','Y'],as_index=False).max()
(After testing a lot of different methods, the simplest one was the best solution (as always) and the one which eluded me the longest. Thanks to @maxymoo for pointing it out.)
来源：https://stackoverflow.com/questions/35020064/reset-index-to-original-column-indices-after-pandas-groupby