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Introduction to Python
course content

Course Content

Introduction to Python

Introduction to Python

1. First Acquaintance
The Very First StepsCommentsSome Simple MathMore Challenging MathChallengeBringing It All Together
2. Variables and Types
Storing NumbersNaming RulesUsing VariablesData TypesNumbersChallengeStoring TextString IndexingNegative Indexing and LengthString SlicingChallengeConcatenation
3. Conditional Statements
Boolean Data TypeChallenge: Comparison OperatorsCombining ConditionsChallenge: Logical OperatorsMembership Operators and Types ComparisonSimple if/else ExpressionsChallenge: Grocery StoreChallenge: Odd and Evenif/elif/else ExpressionsChallenge: Grocery Store ExtendedChallenge: Positive, Negative or Zero
4. Other Data Types
What Is a List?List MethodsChallengeNested ListsChallengeWhat Is a Tuple?Tuple MethodsChallengeNested TuplesChallengeWhat Is a Dictionary?ChallengeDictionary MethodsChallenge
5. Loops
while LoopChallengefor LoopChallengeRangeChallengeIterating Over IndexesNested Loops
6. Functions
Built-in FunctionsChallengeDefining Your First FunctionChallengeif/else Statements in FunctionsChallengeFunctions With No ReturnChallengeModifying FunctionsChallengeLambda FunctionsChallenge

bookModifying Functions

Let's revisit the example with the country information. What happens if the name parameter isn't found in the data?


              
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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')
copy

Can we manage this problem? 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")
copy

Note

d.keys() is a method used with dictionaries that produces a list of all keys in the dictionary d. Here, it's utilized to verify whether the name is present in the dictionary's keys.

As demonstrated, the error message in this updated format is more user-friendly. While there are many other potential errors and methods to handle them, they're outside the purview of this course.

Everything was clear?

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Section 6. Chapter 9
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