How to create a new column based on a condition in Python?

This recipe helps you create a new column based on a condition in Python

In [1]:

## How to create a new column based on a condition in Python
def Kickstarter_Example_81():
    print()
    print(format('How to create a new column based on a condition in Python','*^82'))

    import warnings
    warnings.filterwarnings("ignore")

    # load libraries
    import pandas as pd
    import numpy as np

    # Make a dataframe
    data = {'name': ['Jason', 'Molly', 'Tina', 'Jake', 'Amy'],
            'age': [42, 52, 63, 24, 73],
            'preTestScore': [4, 24, 31, 2, 3],
            'postTestScore': [25, 94, 57, 62, 70]}

    df = pd.DataFrame(data, columns = ['name', 'age', 'preTestScore', 'postTestScore'])
    print(); print(df)

    # Create a new column called df.elderly where the value is yes
    df['elderly@50'] = np.where(df['age']>=50, 'yes', 'no')
    df['elderly@60'] = np.where(df['age']>=60, 'yes', 'no')
    df['elderly@70'] = np.where(df['age']>=70, 'yes', 'no')

    # View the dataframe
    print(); print(df)

Kickstarter_Example_81()

************How to create a new column based on a condition in Python*************

    name  age  preTestScore  postTestScore
0  Jason   42             4             25
1  Molly   52            24             94
2   Tina   63            31             57
3   Jake   24             2             62
4    Amy   73             3             70

    name  age  preTestScore  postTestScore elderly@50 elderly@60 elderly@70
0  Jason   42             4             25         no         no         no
1  Molly   52            24             94        yes         no         no
2   Tina   63            31             57        yes        yes         no
3   Jake   24             2             62         no         no         no
4    Amy   73             3             70        yes        yes        yes