How to subtract by a number the elements of a datafame column with pandas in python ?

How to subtract by a number the elements of a datafame column with pandas in python ?

Daidalos April 14, 2020


Example of how to subtract by a number the elements of a datafame 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

Subtract by a number the elements of a given column

Let's select the column b for example:

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

to subtract by 10 the elements of the column b, a solution is to do

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

References

Links Site
Apply a function to a single column in Dataframe thispointer.com
pandas.DataFrame.apply pandas doc