Given a Pandas dataframe with A as an index:
A B C
1 2 5
2 5 8
3 6 3
4 8 2
Knowing index 3, what is the best way to get:
A B C
1 2 5
2 5 8
3 Nan 3
4 Nan 2
In the real example my index is a datetime and the values are floats, but that hopefully will not affect things.