zip() function in Python - Mini Project: Build & Apply

Using the zip() function to combine lists

📖 Scenario: You work in a small shop and have two lists: one with product names and one with their prices. You want to pair each product with its price to see them together.

🎯 Goal: Learn how to use the zip() function to combine two lists into pairs.

📋 What You'll Learn

Create two lists with exact values

Create a variable to hold the zipped pairs

Use the zip() function correctly

Print the zipped pairs as a list

💡 Why This Matters

🌍 Real World

Combining related data from separate lists is common in shopping apps, inventory systems, and data analysis.

💼 Career

Understanding zip() helps in data processing tasks, making code cleaner and easier to read in many programming jobs.

1

Create two lists of products and prices

Create a list called products with these exact items: 'apple', 'banana', 'cherry'. Then create a list called prices with these exact numbers: 0.99, 0.5, 2.5.

Python

# Create the products list and the prices list
# Your code here

Hint

Use square brackets [] to create lists and separate items with commas.

2

Create a variable to hold zipped pairs

Create a variable called product_price_pairs and set it to the result of zip(products, prices).

Python

products = ['apple', 'banana', 'cherry']
prices = [0.99, 0.5, 2.5]
# Create product_price_pairs using zip(products, prices)
# Your code here

Hint

The zip() function takes two lists and pairs their items by position.

3

Convert zipped pairs to a list

Convert product_price_pairs to a list and store it in a variable called pairs_list.

Python

products = ['apple', 'banana', 'cherry']
prices = [0.99, 0.5, 2.5]
product_price_pairs = zip(products, prices)
# Convert product_price_pairs to a list called pairs_list
# Your code here

Hint

Use the list() function to turn zipped pairs into a list you can see.

4

Print the list of product-price pairs

Print the variable pairs_list to display the combined product and price pairs.

Python

products = ['apple', 'banana', 'cherry']
prices = [0.99, 0.5, 2.5]
product_price_pairs = zip(products, prices)
pairs_list = list(product_price_pairs)
# Print pairs_list
# Your code here

Hint

Use print(pairs_list) to show the final result.

Practice

1. What does the zip() function do in Python?

easy

A. Converts a string to uppercase

B. Sorts a list in ascending order

C. Removes duplicates from a list

D. Combines elements from multiple sequences into pairs or groups

Solution

1. Step 1: Understand the purpose of zip()

   The zip() function takes multiple sequences and pairs their elements by position.

2. Step 2: Compare with other options

   Sorting, removing duplicates, and changing case are unrelated to zip().

3. Final Answer:

   Combines elements from multiple sequences into pairs or groups -> Option D

4. Quick Check:

   zip() pairs sequences [OK]

Hint: Remember: zip pairs elements from sequences together [OK]

Common Mistakes:

• Thinking zip sorts or filters data
• Confusing zip with string methods
• Assuming zip works on single sequences only

2. Which of the following is the correct syntax to use zip() with two lists a and b?

easy

A. zip(a, b)

B. zip[a, b]

C. zip a, b

D. zip(a + b)

Solution

1. Step 1: Recall the function call syntax

   Functions in Python are called with parentheses and arguments separated by commas, like zip(a, b).

2. Step 2: Check other options for syntax errors

   Using square brackets or missing parentheses causes syntax errors or incorrect calls.

3. Final Answer:

   zip(a, b) -> Option A

4. Quick Check:

   Function call uses parentheses [OK]

Hint: Use parentheses and commas to call functions [OK]

Common Mistakes:

• Using square brackets instead of parentheses
• Omitting parentheses
• Trying to add lists inside zip

3. What is the output of the following code?

list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
result = list(zip(list1, list2))
print(result)

medium

A. [(1, 'b'), (2, 'c'), (3, 'a')]

B. [(1, 2, 3), ('a', 'b', 'c')]

C. [(1, 'a'), (2, 'b'), (3, 'c')]

D. [(1, 'a'), (2, 'b')]

Solution

1. Step 1: Understand how zip() pairs elements

   It pairs elements by position: first with first, second with second, etc.

2. Step 2: Apply to given lists

   Pairs are (1, 'a'), (2, 'b'), (3, 'c').

3. Final Answer:

   [(1, 'a'), (2, 'b'), (3, 'c')] -> Option C

4. Quick Check:

   Pairs match positions [OK]

Hint: zip pairs elements by index until shortest list ends [OK]

Common Mistakes:

• Confusing zip with concatenation
• Mixing element order in pairs
• Expecting zip to combine all elements into one tuple

4. Identify the error in this code snippet:

list1 = [1, 2]
list2 = ['x', 'y', 'z']
for a, b, c in zip(list1, list2):
    print(a, b, c)

medium

A. zip() requires lists of the same length

B. Too many variables to unpack in the for loop

C. Missing parentheses in zip call

D. print statement syntax error

Solution

1. Step 1: Check the number of variables in the for loop

   The loop tries to unpack three variables (a, b, c) from each zipped tuple.

2. Step 2: Check what zip produces

   zip(list1, list2) produces tuples with 2 elements each, so unpacking 3 variables causes an error.

3. Final Answer:

   Too many variables to unpack in the for loop -> Option B

4. Quick Check:

   Unpack count must match tuple size [OK]

Hint: Unpack only as many variables as zipped sequences [OK]

Common Mistakes:

• Assuming zip requires equal length lists
• Forgetting zip returns tuples of length equal to input sequences count
• Ignoring Python unpacking rules

5. Given two lists:

names = ['Anna', 'Bob', 'Cathy', 'Dan']
scores = [85, 92, 78]

Which code correctly creates a dictionary pairing each name with their score, ignoring extra names?

hard

A. dict(zip(names, scores))

B. {names[i]: scores[i] for i in range(len(names))}

C. dict(zip(scores, names))

D. dict(zip(names + scores))

Solution

1. Step 1: Understand zip behavior with unequal lengths

   zip stops at the shortest list length, so extra names are ignored.

2. Step 2: Check dictionary creation

   Using dict(zip(names, scores)) pairs names with scores correctly.

3. Step 3: Analyze other options

   {names[i]: scores[i] for i in range(len(names))} causes IndexError (longer names list). dict(zip(scores, names)) reverses keys and values. dict(zip(names + scores)) is invalid syntax.

4. Final Answer:

   dict(zip(names, scores)) -> Option A

5. Quick Check:

   zip stops at shortest list, dict pairs correctly [OK]

Hint: Use dict(zip(keys, values)) to pair lists safely [OK]

Common Mistakes:

• Assuming zip fills missing values
• Reversing keys and values in dict
• Using invalid syntax for zip