Pandas Apply Function That returns two new columns

Question

I have a pandas dataframe that I would like to use an apply function on to generate two new columns based on the existing data. I am getting this error: ValueError: Wrong number of items passed 2, placement implies 1

import pandas as pd
import numpy as np

def myfunc1(row):
    C = row['A'] + 10
    D = row['A'] + 50
    return [C, D]

df = pd.DataFrame(np.random.randint(0,10,size=(2, 2)), columns=list('AB'))

df['C', 'D'] = df.apply(myfunc1 ,axis=1)

Starting DF:

   A  B
0  6  1
1  8  4

Desired DF:

   A  B  C   D
0  6  1  16  56
1  8  4  18  58

Answer 1

Based on your latest error, you can avoid the error by returning the new columns as a Series

def myfunc1(row):
    C = row['A'] + 10
    D = row['A'] + 50
    return pd.Series([C, D])

df[['C', 'D']] = df.apply(myfunc1 ,axis=1)