Merge pull request #661 from realpython/python-set

brendaweles · web-flow · commit 80e5421f6aa2 · 2025-04-25T16:55:26.000-06:00
Sample code for the article on sets
diff --git a/python-set/README.md b/python-set/README.md
@@ -0,0 +1,3 @@
+# Sets in Python
+
+This folder provides the code examples for the Real Python tutorial [Sets in Python](https://realpython.com/python-set/).
diff --git a/python-set/add.py b/python-set/add.py
@@ -0,0 +1,6 @@
+employees = {"Alice", "Charlie"}
+employees.add("John")
+employees.add("Laura")
+employees.add("John")
+# employees.add("Jane", "Bob")
+print(employees)
diff --git a/python-set/clear.py b/python-set/clear.py
@@ -0,0 +1,3 @@
+employees = {"Alice", "Charlie", "John", "Laura"}
+employees.clear()
+print(employees)
diff --git a/python-set/comprehensions.py b/python-set/comprehensions.py
@@ -0,0 +1,2 @@
+usernames = ["Alice", " bob", "ALICE  ", "Bob", "charlie", "Charlie", "JOHN"]
+print({name.lower().strip() for name in usernames})
diff --git a/python-set/difference.py b/python-set/difference.py
@@ -0,0 +1,10 @@
+registered_users = {"Alice", "Bob", "Charlie", "Diana", "Linda"}
+checked_in_users = {"Alice", "Charlie", "Linda"}
+print(registered_users - checked_in_users)
+print(registered_users.difference(checked_in_users))
+
+a = {1, 2, 3, 30, 300}
+b = {10, 20, 30, 40}
+c = {100, 200, 300, 400}
+print(a - b - c)
+print(a.difference(b, c))
diff --git a/python-set/difference_update.py b/python-set/difference_update.py
@@ -0,0 +1,9 @@
+todo_list = {
+    "Implement user login",
+    "Fix bug #123",
+    "Improve performance",
+    "Write unit tests",
+}
+completed_tasks = {"Fix bug #123", "Improve performance"}
+todo_list.difference_update(completed_tasks)
+todo_list
diff --git a/python-set/discard.py b/python-set/discard.py
@@ -0,0 +1,4 @@
+employees = {"Alice", "Charlie", "John", "Laura"}
+employees.discard("Alice")
+employees.discard("Linda")
+print(employees)
diff --git a/python-set/disjoint.py b/python-set/disjoint.py
@@ -0,0 +1,22 @@
+def verify_purchase(age, selection, restricted_products):
+    if age < 21 and not selection.isdisjoint(restricted_products):
+        print("Purchase denied: selection includes age-restricted products")
+    else:
+        print("Purchase approved")
+
+
+verify_purchase(
+    age=18,
+    selection={"milk", "bread", "beer"},
+    restricted_products={"alcohol", "beer", "cigarettes"},
+)
+verify_purchase(
+    age=18,
+    selection={"milk", "bread"},
+    restricted_products={"alcohol", "beer", "cigarettes"},
+)
+verify_purchase(
+    age=35,
+    selection={"milk", "bread", "beer"},
+    restricted_products={"alcohol", "beer", "cigarettes"},
+)
diff --git a/python-set/intersection.py b/python-set/intersection.py
@@ -0,0 +1,13 @@
+john_friends = {"Linda", "Mathew", "Carlos", "Laura"}
+jane_friends = {"Alice", "Bob", "Laura", "Mathew"}
+
+print(john_friends & jane_friends)
+print(john_friends.intersection(jane_friends))
+
+a = {1, 2, 3, 4}
+b = {2, 3, 4, 5}
+c = {3, 4, 5, 6}
+d = {4, 5, 6, 7}
+
+print(a & b & c & d)
+print(a.intersection(b, c, d))
diff --git a/python-set/intersection_update.py b/python-set/intersection_update.py
@@ -0,0 +1,10 @@
+accepted_emails = {"Bob", "Diana", "Charlie"}
+target_customers = {"Alice", "Bob", "Charlie", "Diana", "Jane"}
+target_customers &= accepted_emails
+print(target_customers)
+
+# Or
+
+target_customers = {"Alice", "Bob", "Charlie", "Diana", "Jane"}
+target_customers.intersection_update(accepted_emails)
+print(target_customers)
diff --git a/python-set/iteration.py b/python-set/iteration.py
@@ -0,0 +1,38 @@
+employees = {"Alice", "Charlie", "John", "Laura"}
+for employee in employees:
+    print(f"Hello, {employee}!")
+
+employees = {"Alice", "Charlie", "John", "Laura"}
+uppercase = set()
+for employee in employees:
+    uppercase.add(employee.upper())
+
+print(uppercase)
+
+employees = {"Alice", "Charlie", "John", "Laura"}
+employees = {employee.upper() for employee in employees}
+print(employees)
+
+available_seats = {"A1", "A2", "B1", "B2", "C1"}
+while available_seats:
+    assigned_seat = available_seats.pop()
+    print(f"Seat {assigned_seat} was assigned")
+
+print(available_seats)
+
+cities = {"Vancouver", "Berlin", "London", "Warsaw", "Vienna"}
+for city in sorted(cities):
+    print(city)
+
+cities = {
+    ("Vancouver", 675000),
+    ("Berlin", 3800000),
+    ("London", 8980000),
+    ("Warsaw", 1790000),
+    ("Vienna", 1900000),
+}
+for city in sorted(cities, key=lambda city: city[1]):
+    print(city)
+
+for city in sorted(cities, key=lambda city: city[1], reverse=True):
+    print(city)
diff --git a/python-set/literals.py b/python-set/literals.py
@@ -0,0 +1,27 @@
+numbers = [1, 2, 2, 2, 3, 4, 5, 5]
+print(set(numbers))
+
+# Single-element set
+hex_colors = {"#33FF57"}
+print(hex_colors)
+
+# Multiple-element set
+hex_colors = {
+    "#33FF57",  # Green
+    "#3357FF",  # Blue
+    "#F1C40F",  # Yellow
+    "#E74C3C",  # Red
+}
+print(hex_colors)
+
+rgb_colors = {
+    (51, 255, 87),  # Green
+    (51, 87, 255),  # Blue
+    (241, 196, 15),  # Yellow
+    (231, 76, 60),  # Red
+}
+print(rgb_colors)
+
+print({2, 4, 6, 8, 10, 8, 2})
+print({"Smith", "McArthur", "Wilson", "Johansson", "Smith"})
+print({42, "Hi!", 3.14159, None, "Python"})
diff --git a/python-set/membership.py b/python-set/membership.py
@@ -0,0 +1,18 @@
+import random
+import time
+
+numbers_list = list(range(1_000_000))
+numbers_set = set(range(1_000_000))
+number_to_check = [random.randint(0, 999_999) for _ in range(1_000)]
+
+start = time.perf_counter()
+for number in number_to_check:
+    _ = number in numbers_list
+end = time.perf_counter()
+print(f"List membership check took {end - start:.4f} seconds")
+
+start = time.perf_counter()
+for number in number_to_check:
+    _ = number in numbers_set
+end = time.perf_counter()
+print(f"Set membership check took {end - start:.4f} seconds")
diff --git a/python-set/pop.py b/python-set/pop.py
@@ -0,0 +1,6 @@
+employees = {"Alice", "Charlie", "John", "Laura"}
+print(employees.pop())
+print(employees.pop())
+employees.pop()
+employees.pop()
+employees.pop()
diff --git a/python-set/proper_subset.py b/python-set/proper_subset.py
@@ -0,0 +1,6 @@
+regular_plan = {"Tutorials", "Quizzes"}
+premium_plan = {"Tutorials", "Video Courses", "Quizzes", "Books"}
+print(regular_plan < premium_plan)
+
+a = {1, 2, 3, 4, 5}
+print(a < a)
diff --git a/python-set/proper_superset.py b/python-set/proper_superset.py
@@ -0,0 +1,6 @@
+regular_plan = {"Tutorials", "Quizzes"}
+premium_plan = {"Tutorials", "Video Courses", "Quizzes", "Books"}
+print(premium_plan > regular_plan)
+
+a = {1, 2, 3, 4, 5}
+print(a > a)
diff --git a/python-set/remove.py b/python-set/remove.py
@@ -0,0 +1,4 @@
+employees = {"Alice", "Charlie", "John", "Laura"}
+employees.remove("Charlie")
+employees.remove("Linda")
+print(employees)
diff --git a/python-set/subset.py b/python-set/subset.py
@@ -0,0 +1,9 @@
+required_ingredients = {"cheese", "eggs", "milk"}
+available_ingredients = {"cheese", "eggs", "milk", "sugar", "salt"}
+
+print(required_ingredients <= available_ingredients)
+print(required_ingredients.issubset(available_ingredients))
+
+a = {1, 2, 3, 4, 5}
+print(a <= a)
+print(a.issubset(a))
diff --git a/python-set/superset.py b/python-set/superset.py
@@ -0,0 +1,9 @@
+required_ingredients = {"cheese", "eggs", "milk"}
+available_ingredients = {"cheese", "eggs", "milk", "sugar", "salt"}
+
+print(available_ingredients >= required_ingredients)
+print(available_ingredients.issubset(required_ingredients))
+
+a = {1, 2, 3, 4, 5}
+print(a.issuperset(a))
+print(a >= a)
diff --git a/python-set/symmetric_difference.py b/python-set/symmetric_difference.py
@@ -0,0 +1,10 @@
+morning_attendees = {"Alice", "Charlie", "Linda", "John", "Jane"}
+afternoon_attendees = {"Charlie", "Linda", "Bob", "Jane"}
+
+print(morning_attendees ^ afternoon_attendees)
+print(morning_attendees.symmetric_difference(afternoon_attendees))
+
+a = {1, 2, 3, 4, 5}
+b = {10, 2, 3, 4, 50}
+c = {1, 50, 100}
+print(a ^ b ^ c)
diff --git a/python-set/symmetric_difference_update.py b/python-set/symmetric_difference_update.py
@@ -0,0 +1,9 @@
+morning_attendees = {"Alice", "Charlie", "Linda", "John", "Jane"}
+afternoon_attendees = {"Charlie", "Linda", "Bob", "Jane"}
+whole_day_attendees = set()
+
+whole_day_attendees ^= morning_attendees
+print(whole_day_attendees)
+
+whole_day_attendees.symmetric_difference_update(afternoon_attendees)
+print(whole_day_attendees)
diff --git a/python-set/union.py b/python-set/union.py
@@ -0,0 +1,12 @@
+pet_animals = {"dog", "cat", "hamster", "parrot"}
+farm_animals = {"cow", "chicken", "goat", "dog", "cat"}
+
+print(pet_animals | farm_animals)
+print(pet_animals.union(farm_animals))
+
+a = {1, 2, 3, 4}
+b = {2, 3, 4, 5}
+c = {3, 4, 5, 6}
+d = {4, 5, 6, 7}
+a.union(b, c, d)
+print(a | b | c | d)
diff --git a/python-set/update.py b/python-set/update.py
@@ -0,0 +1,10 @@
+checked_in_attendees = set()
+print(id(checked_in_attendees))
+
+checked_in_attendees |= {"Alice", "Charlie"}
+print(checked_in_attendees)
+print(id(checked_in_attendees))
+
+checked_in_attendees.update({"Linda", "Bob"})
+print(checked_in_attendees)
+print(id(checked_in_attendees))

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+# Sets in Python`
	`2`	`+`
	`3`	`+This folder provides the code examples for the Real Python tutorial [Sets in Python](https://realpython.com/python-set/).`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+employees = {"Alice", "Charlie", "John", "Laura"}`
	`2`	`+employees.clear()`
	`3`	`+print(employees)`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+usernames = ["Alice", " bob", "ALICE ", "Bob", "charlie", "Charlie", "JOHN"]`
	`2`	`+print({name.lower().strip() for name in usernames})`