I have the following dataframe: import pandas as pd import numpy as np df = pd.DataFrame({ 'Name': ['A','B','A','B','A','B','A','B'], 'Include':[np.nan,np.nan,np.nan,np.nan,np.nan,np.nan,np.nan,np.nan], 'Category':['Cat','Dog','Car','Dog','Bike','Dog','Cat','Bike'], }) df I am trying to fill the Include column with the string yes if the column Category does not match the following list: exluded = ['Car','Bike'] So that my expected output is this: Any ideas of how to achieve this? Continue reading...