Summary  
This chapter explains how to use the add() method to insert one element at a time into a set, with each call adding exactly one unique item and ignoring duplicates.

General domain of usage  
managing collections of unique data

You can also add elements to a set. To do this, there's a specific `add()` method. It's important to note that with this method, you can add **only one element** at a time. So, if you want to add 4 elements, for example, you'll need to use this method 4 times. Let's check out an example.

# Creating an empty set
favorite_movies = set()
print("Initial set:", favorite_movies)  # Output - Initial set: set()

# Adding movies to the set
favorite_movies.add("Inception")
favorite_movies.add("Interstellar")
favorite_movies.add("Tenet")
favorite_movies.add("Dunkirk")

print("Updated set:", favorite_movies)  # Output - Updated set: {'Interstellar', 'Dunkirk', 'Inception', 'Tenet'}

The `add()` method is best used for adding **single** elements.

import unittest
import importlib

def _dynamic_test(test_case, condition, success_message, failure_message):
    if condition:
        test_case._testMethodName = success_message
        test_case.assertTrue(True, success_message)
    else:
        test_case._testMethodName = failure_message
        test_case.fail(failure_message)

class TestUserCode(unittest.TestCase):
    def test_tarantino_movies_is_declared(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code, 'tarantino_movies'),
            "The `tarantino_movies` set is declared.",
            "Expected `tarantino_movies` to be declared."
        )

    def test_tarantino_movies_is_set(self):
        import user_code
        _dynamic_test(
            self,
            isinstance(user_code.tarantino_movies, set),
            "The `tarantino_movies` is of type `set`.",
            "Expected `tarantino_movies` to be of type `set`."
        )

    def test_tarantino_movies_contains_initial_movies(self):
        import user_code
        initial_movies = {
            'Pulp Fiction',
            'Kill Bill: Vol. 1',
            'Kill Bill: Vol. 2',
            'Inglourious Basterds',
            'Django Unchained'
        }
        _dynamic_test(
            self,
            initial_movies.issubset(user_code.tarantino_movies),
            f"The `tarantino_movies` contains the initial movies: {initial_movies}.",
            f"Expected `tarantino_movies` to contain the initial movies: {initial_movies}, but got {user_code.tarantino_movies}."
        )

    def test_tarantino_movies_contains_new_movies(self):
        import user_code
        new_movies = {'Reservoir Dogs', 'Once Upon a Time in Hollywood'}
        _dynamic_test(
            self,
            new_movies.issubset(user_code.tarantino_movies),
            f"The `tarantino_movies` contains the newly added movies: {new_movies}.",
            f"Expected `tarantino_movies` to contain the newly added movies: {new_movies}, but got {user_code.tarantino_movies}."
        )

    def test_add_method_used(self):
        with open('user_code.py', 'r') as file:
            user_code_source = file.read()
        _dynamic_test(
            self,
            user_code_source.count("add") >= 2,
            "The `add()` method is used at least twice to add new movies.",
            "Expected the `add()` method to be used at least twice to add new movies."
        )

if __name__ == '__main__':
    unittest.main()


test_main.py

In this course, you'll get to know the fundamental data structures of the Python programming language. We'll explore utilizing Python's native data structures like lists, dictionaries, tuples, and sets to tackle different challenges.

What is a list? A list is an ordered collection that can be modified. It also allows for duplicate elements.

What is a dictionary? A dictionary is an ordered collection that can be changed, but it doesn't allow duplicate entries. It consists of `key:value` pairs, which are used to optimize its structure.

What is a tuple? A tuple is an ordered collection that cannot be altered. It can have duplicate elements. While it's similar to a list, the values in a tuple can be of any type and are indexed by integers. Although not mandatory, it's common to enclose the values of a tuple in parentheses, making them easier to understand in Python.

What is a set? In Python, a `set` is an unordered collection that is both `iterable` and `mutable`, with no repeated elements. While the order of items in a set isn't fixed, it can include a variety of elements. A key benefit of using sets over lists is their highly efficient method for determining if an element exists within the set.

Using the add() Method: Adding Single Elements to a Set

Solution

Awesome!

Using the add() Method: Adding Single Elements to a Set

Solution