MultiIndex Pandas不对第一级索引进行分组

Question

I am trying to create a Pandas Dataframe with two levels of index in the rows.

info = pd.DataFrame([['A', 1, 3],
                   ['A', 2, 4],
                   ['A', 3, 6],
                   ['B', 1, 9],
                   ['B', 2, 10],
                   ['B', 4, 6]], columns=pd.Index(['C', 'D', 'V'])    
info_new = info.set_index(['C', 'D'], drop=False)

EDIT: I want the following output:

     V
C  D
A  1 3
   2 4
   3 6
B  1 9
   2 10
   4 6

According to every instruction I found, this should work. I am still getting

     V
C  D
A  1 3
A  2 4
A  3 6
B  1 9
B  2 10
B  4 6

So apparently, the multiindex does not work here.

I checked each column with non-unique values with .is_unique , the answer is False. I checked the columns with unique values, the answer is True. I also tried to assign a dtype=str, this didn't change anything.

Answer 1

Thank you for the info_new.index.is_lexsorted() comment.

I solved it by specifying dtype=str in the .csv import and then:

info_new.sortlevel(inplace=True)