create a variable based on a condition using pandas in python

To create a variable based on a condition using pandas in Python, you can use the np.where() function from the numpy library, which is commonly used with pandas.

Here is an example of how to create a new variable new_var based on a condition in a pandas DataFrame df:

main.py
import pandas as pd
import numpy as np

# Create a DataFrame
df = pd.DataFrame({'A': [10, 20, 30, 40, 50]})

# Create a new variable based on a condition
df['new_var'] = np.where(df['A'] > 30, 'Greater than 30', 'Less than or equal to 30')

# Print the DataFrame
print(df)
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In this example, the condition is df['A'] > 30. If the condition is True, the corresponding value 'Greater than 30' is assigned to the new variable new_var, and if the condition is False, the corresponding value 'Less than or equal to 30' is assigned.

The resulting DataFrame will have the new variable new_var along with the original column A.

Output:

main.py
    A                   new_var
0  10    Less than or equal to 30
1  20    Less than or equal to 30
2  30    Less than or equal to 30
3  40          Greater than 30
4  50          Greater than 30
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By using np.where(), you can flexibly assign values based on conditions in pandas. Keep in mind that you can customize your conditions according to your specific requirements.