I would like to add a column to the second level of a multiindex column dataframe.
In [151]: df
Out[151]:
first bar baz
second one two one two
A 0.487880 -0.487661 -1.030176 0.100813
B 0.267913 1.918923 0.132791 0.178503
C 1.550526 -0.312235 -1.177689 -0.081596
The usual trick of direct assignment does not work:
In [152]: df['bar']['three'] = [0, 1, 2]
In [153]: df
Out[153]:
first bar baz
second one two one two
A 0.487880 -0.487661 -1.030176 0.100813
B 0.267913 1.918923 0.132791 0.178503
C 1.550526 -0.312235 -1.177689 -0.081596
How can I add the third row to under "bar"?
It's actually pretty simple (FWIW, I originally thought to do it your way):
df['bar', 'three'] = [0, 1, 2]
df = df.sort_index(axis=1)
print(df)
bar baz
one two three one two
A -0.212901 0.503615 0 -1.660945 0.446778
B -0.803926 -0.417570 1 -0.336827 0.989343
C 3.400885 -0.214245 2 0.895745 1.011671