List comprehension vs loop in Python - Hands-On Comparison

List comprehension vs loop

📖 Scenario: You work in a small bakery. Every day, you record the number of cookies sold in a list. You want to find out how many cookies you sold each day after giving a 10% discount on the price per cookie.

🎯 Goal: Build a program that calculates the discounted cookie prices using both a for loop and a list comprehension. Compare the results.

📋 What You'll Learn

Create a list called cookie_prices with exact values: 2.0, 2.5, 3.0, 2.75, 3.25

Create a variable called discount_rate and set it to 0.10

Use a for loop with variable price to create a list called discounted_prices_loop with prices after discount

Use a list comprehension with variable price to create a list called discounted_prices_comp with prices after discount

Print both discounted_prices_loop and discounted_prices_comp

💡 Why This Matters

🌍 Real World

Calculating discounts on product prices is common in stores and online shops to attract customers.

💼 Career

Understanding loops and list comprehensions helps in data processing tasks, which are common in programming jobs.

1

Create the list of cookie prices

Create a list called cookie_prices with these exact values: 2.0, 2.5, 3.0, 2.75, 3.25

Python

# Create the list cookie_prices with the exact values
# Your code here

Need a hint?

Use square brackets [] to create a list with the given numbers separated by commas.

2

Set the discount rate

Create a variable called discount_rate and set it to 0.10

Python

cookie_prices = [2.0, 2.5, 3.0, 2.75, 3.25]
# Create the variable discount_rate and set it to 0.10
# Your code here

Need a hint?

Use the equals sign = to assign the value 0.10 to the variable discount_rate.

3

Calculate discounted prices using a for loop and a list comprehension

Use a for loop with variable price to create a list called discounted_prices_loop with prices after discount. Then use a list comprehension with variable price to create a list called discounted_prices_comp with prices after discount.

Python

cookie_prices = [2.0, 2.5, 3.0, 2.75, 3.25]
discount_rate = 0.10
# Use a for loop with price to create discounted_prices_loop
# Use a list comprehension with price to create discounted_prices_comp
# Your code here

Need a hint?

In the for loop, multiply each price by (1 - discount_rate) and add it to discounted_prices_loop. In the list comprehension, do the same calculation inside square brackets.

4

Print the discounted prices lists

Print the list discounted_prices_loop and then print the list discounted_prices_comp

Python

cookie_prices = [2.0, 2.5, 3.0, 2.75, 3.25]
discount_rate = 0.10

discounted_prices_loop = []
for price in cookie_prices:
    discounted_price = price * (1 - discount_rate)
    discounted_prices_loop.append(discounted_price)

discounted_prices_comp = [price * (1 - discount_rate) for price in cookie_prices]

# Print discounted_prices_loop
# Print discounted_prices_comp
# Your code here

Need a hint?

Use two print statements, one for each list.