Create a Column Based on a Conditional in pandas

Preliminaries

# Import required modules
import pandas as pd
import numpy as np

Make a dataframe

data = {'name': ['Jason', 'Molly', 'Tina', 'Jake', 'Amy'], 
        'age': [42, 52, 36, 24, 73], 
        'preTestScore': [4, 24, 31, 2, 3],
        'postTestScore': [25, 94, 57, 62, 70]}
df = pd.DataFrame(data, columns = ['name', 'age', 'preTestScore', 'postTestScore'])
df
name age preTestScore postTestScore
0 Jason 42 4 25
1 Molly 52 24 94
2 Tina 36 31 57
3 Jake 24 2 62
4 Amy 73 3 70

5 rows × 4 columns

Add a new column for elderly

# Create a new column called df.elderly where the value is yes
# if df.age is greater than 50 and no if not
df['elderly'] = np.where(df['age']>=50, 'yes', 'no')
# View the dataframe
df
name age preTestScore postTestScore elderly
0 Jason 42 4 25 no
1 Molly 52 24 94 yes
2 Tina 36 31 57 no
3 Jake 24 2 62 no
4 Amy 73 3 70 yes

5 rows × 5 columns