How to add a constant number to a DataFrame column with pandas in python ?

Example of how to add a constant number to a DataFrame column with pandas in python

Create a simple Data frame

Let's create a data frame with pandas called df:

>>> import pandas as pd
>>> import numpy as np
>>> data = np.arange(1,13)
>>> data = data.reshape(3,4)
>>> df = pd.DataFrame(data=data,columns=['a','b','c','d'])
>>> df
   a   b   c   d
0  1   2   3   4
1  5   6   7   8
2  9  10  11  12

Add a constant number to each column elements

Let's select the column b for example:

>>> df['b']
0     2
1     6
2    10

to add 10 to each element, a solution is to do:

>>> df['b'] = df['b'] + 10
>>> df
   a   b   c   d
0  1  12   3   4
1  5  16   7   8
2  9  20  11  12

References