pandas if contains replace code example

Example: replace string if it contains a substring pandas

df_a.loc[df_a.categories.str.contains('beverage'), 'categories'] = 'beverage'


    categories      product_name
0   beverage        coca-cola
1   salty snacks    salted pistachios
2   beverage        fruit juice
3   beverage        lemon tea
4   salty crackers  roasted peanuts