grouping rows in list in pandas groupby

I have a pandas data frame like:

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

I want to group by the first column and get second column as lists in rows:

    A [1,2]
    B [5,5,4]
    C [6]

Is it possible to do something like this using pandas groupby?

You can do this using groupby to group on the column of interest and then apply list to every group:

    In [1]:
    # create the dataframe    
    df = pd.DataFrame( {'a':['A','A','B','B','B','C'], 'b':[1,2,5,5,4,6]})
    df
    Out[1]:
       a  b
    0  A  1
    1  A  2
    2  B  5
    3  B  5
    4  B  4
    5  C  6

    [6 rows x 2 columns]

    In [76]:
    df.groupby('a')['b'].apply(list)

    Out[76]:
    a
    A       [1, 2]
    B    [5, 5, 4]
    C          [6]
    Name: b, dtype: object

From: stackoverflow.com/q/22219004