Nested list comprehension in Python - Mini Project: Build & Apply

Nested list comprehension

📖 Scenario: You work in a bakery that sells boxes of assorted cookies. Each box contains several types of cookies, and you want to create a simple list showing all cookie types available in all boxes.

🎯 Goal: Build a nested list comprehension to flatten a list of cookie boxes into a single list of cookie types.

📋 What You'll Learn

Create a list of lists called cookie_boxes with exact cookie types

Create a variable called all_cookies using nested list comprehension

Print the all_cookies list

💡 Why This Matters

🌍 Real World

Bakeries and stores often have grouped data like boxes or categories. Flattening such data helps in searching or displaying all items easily.

💼 Career

Understanding nested list comprehension is useful for data processing jobs, where you often work with nested or grouped data structures.

1

Create the cookie boxes data

Create a list called cookie_boxes with these exact lists inside: ["chocolate chip", "oatmeal"], ["peanut butter", "snickerdoodle"], and ["sugar", "gingersnap"].

Python

# Create the list cookie_boxes with the exact cookie types
# Your code here

Need a hint?

Remember, cookie_boxes is a list containing three lists, each with two cookie names as strings.

2

Prepare the variable for all cookies

Create an empty list called all_cookies to hold all cookie types before using list comprehension.

Python

cookie_boxes = [["chocolate chip", "oatmeal"], ["peanut butter", "snickerdoodle"], ["sugar", "gingersnap"]]
# Create an empty list called all_cookies
# Your code here

Need a hint?

Just create a variable named all_cookies and set it to an empty list [].

3

Use nested list comprehension to flatten the list

Use nested list comprehension to fill all_cookies with every cookie from each box in cookie_boxes. Use all_cookies = [cookie for box in cookie_boxes for cookie in box] exactly.

Python

cookie_boxes = [["chocolate chip", "oatmeal"], ["peanut butter", "snickerdoodle"], ["sugar", "gingersnap"]]
all_cookies = []
# Use nested list comprehension to fill all_cookies
# Your code here

Need a hint?

Remember the order: first loop over each box in cookie_boxes, then over each cookie in that box.

4

Print the list of all cookies

Print the all_cookies list using print(all_cookies).

Python

cookie_boxes = [["chocolate chip", "oatmeal"], ["peanut butter", "snickerdoodle"], ["sugar", "gingersnap"]]
all_cookies = [cookie for box in cookie_boxes for cookie in box]
# Print the all_cookies list
# Your code here

Need a hint?

Use the print() function to show the list.