Statement
Solution
Python Exercise 10.2: Lambda Sorting
Lambda functions are small, anonymous functions defined inline with the lambda keyword. They're especially useful as the key argument to sorted() or list.sort() when you need a custom sort order.
Your program should:
- Start with a list of product tuples in the format
(name, price):[("Laptop", 999), ("Mouse", 25), ("Monitor", 349), ("Keyboard", 79), ("Webcam", 59)] - Use
sorted()with a lambda function as thekeyto sort by price in ascending order. Print the result. - Sort again by price in descending order using the
reverse=Trueargument. Print the result. - Bonus: Sort alphabetically by product name and print the result.
Sample Interaction:
Input
Output
(None)
Sorted by price (low to high):
('Mouse', 25)
('Webcam', 59)
('Keyboard', 79)
('Monitor', 349)
('Laptop', 999)
Sorted by price (high to low):
('Laptop', 999)
('Monitor', 349)
('Keyboard', 79)
('Webcam', 59)
('Mouse', 25)
Sorted by name (A-Z):
('Keyboard', 79)
('Laptop', 999)
('Monitor', 349)
('Mouse', 25)
('Webcam', 59)
Solution
A lambda extracts the sort key from each tuple on the fly — no need to write a separate named function.
products = [
("Laptop", 999),
("Mouse", 25),
("Monitor", 349),
("Keyboard", 79),
("Webcam", 59)
]
# Sort by price ascending
by_price_asc = sorted(products, key=lambda p: p[1])
print("Sorted by price (low to high):")
for item in by_price_asc:
print(item)
# Sort by price descending
by_price_desc = sorted(products, key=lambda p: p[1], reverse=True)
print("\nSorted by price (high to low):")
for item in by_price_desc:
print(item)
# Bonus: sort alphabetically by name
by_name = sorted(products, key=lambda p: p[0])
print("\nSorted by name (A-Z):")
for item in by_name:
print(item)
Key Concepts:
lambda args: expressioncreates an anonymous single-expression function.sorted(iterable, key=...)returns a new sorted list; the original is unchanged.key=lambda p: p[1]tells Python to sort by the second element of each tuple (index 1 = price).reverse=Trueflips the sort to descending without any extra logic.- Lambda functions are equivalent to a
deffunction with a singlereturnstatement — just more concise.
Test Console
Run code to see output...
