Modifying Functions in Python

Reconsider the example with the country information. What happens if the provided name parameter isn't found in the dataset?


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# Data
countries_dict = {'USA': (9629091, 331002651), 'Canada': (9984670, 37742154), 
                  'Germany': (357114, 83783942), 'Brazil': (8515767, 212559417), 
                  'India': (3166391, 1380004385)}

# Defining a function
def country_information(d, name):
  print('Country:', name)
  print('Area:', d[name][0], 'sq km')
  print('Population:', round(d[name][1]/1000000, 2), 'MM')

# Testing the function
country_information(countries_dict, 'USA')
country_information(countries_dict, 'Ukraine')

Can we handle this situation? Absolutely, by implementing conditional statements!


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# Data
countries_dict = {'USA': (9629091, 331002651), 'Canada': (9984670, 37742154), 
                  'Germany': (357114, 83783942), 'Brazil': (8515767, 212559417), 
                  'India': (3166391, 1380004385)}

# Modify our function
def country_information_mod(d, name):
  if name not in d.keys():
    print("There is no information about", name)
  else:
    print("Country:", name)
    print("Area:", d[name][0], 'sq km')
    print("Population:", round(d[name][1]/1000000, 2), 'mln')
        
# Testing the function
country_information_mod(countries_dict, "USA")
country_information_mod(countries_dict, "Ukraine")

Note

The method d.keys() is a dictionary method that returns a view containing all the keys from the dictionary d. Here, it's used to check whether the provided name exists among the dictionary's keys.

As demonstrated, the error message in this revised format is more user-friendly. Although many other potential errors exist, there are numerous methods to handle them.

Everything was clear?

Thanks for your feedback!

Section 6. Chapter 9