Add Multiple Columns to Pandas Dataframe from Function

Question

I have a pandas data frame mydf that has two columns,and both columns are datetime datatypes: mydate and mytime. I want to add three more

Answer 1

You can do this in a somewhat cleaner method by having the function you apply return a pd.Series with named elements:

def process(row):
    return pd.Series(dict(b=row["a"] * 2, c=row["a"] + 2))


my_df = pd.DataFrame(dict(a=range(10)))
new_df = my_df.join(my_df.apply(process, axis="columns"))

The result is:

   a   b   c
0  0   0   2
1  1   2   3
2  2   4   4
3  3   6   5
4  4   8   6
5  5  10   7
6  6  12   8
7  7  14   9
8  8  16  10
9  9  18  11