Make new column in Panda dataframe by adding values from other columns

Question

I have a dataframe with values like

A B
1 4
2 6
3 9

I need to add a new column by adding values from column A and B, like

Answer 1

You could use sum function to achieve that as @EdChum mentioned in the comment:

df['C'] =  df[['A', 'B']].sum(axis=1)

In [245]: df
Out[245]: 
   A  B   C
0  1  4   5
1  2  6   8
2  3  9  12