How to group dataframe rows into list in pandas groupby

Question

I have a pandas data frame df like:

a b
A 1
A 2
B 5
B 5
B 4
C 6

I want to group by the first column and get second col

Answer 1

The easiest way I have see no achieve most of the same thing at least for one column which is similar to Anamika's answer just with the tuple syntax for the aggregate function.

df.groupby('a').agg(b=('b','unique'), c=('c','unique'))