zip() function in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to combine two lists into pairs using the zip() function.

Python

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

Drag options to blanks, or click blank then click option'

Afilter

Brange

Cmap

Dzip

Attempts:

3 left

💡 Hint

Common Mistakes

Using range() instead of zip() causes a TypeError when printing.

Using map() or filter() won't combine lists into pairs.

The zip() function pairs elements from two lists together. Here, it combines list1 and list2 into pairs.

2fill in blank

medium

Complete the code to print pairs of elements from two lists using zip() in a for loop.

Python

names = ['Alice', 'Bob', 'Charlie']
ages = [25, 30, 35]
for [1], age in zip(names, ages):
    print(f"{name} is {age} years old")

Drag options to blanks, or click blank then click option'

Aages

Bnames

Cname

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'names' instead of 'name' causes confusion because 'names' is the whole list.

Using 'age' or 'ages' for the first variable is incorrect because it matches the second list.

The variable name holds each element from the names list during iteration. It matches the first item from each pair created by zip().

3fill in blank

hard

Fix the error in the code by completing the blank to correctly unzip a list of pairs.

Python

pairs = [(1, 'a'), (2, 'b'), (3, 'c')]
numbers, letters = zip(*[1])
print(numbers)
print(letters)

Drag options to blanks, or click blank then click option'

Apairs

Blist

Czip

Denumerate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'list' causes a TypeError because it's a type, not the variable.

Using 'zip' or 'enumerate' causes errors because they are functions, not the data.

The * operator unpacks the list of pairs. We need to unpack the variable pairs to unzip the elements into separate tuples.

4fill in blank

hard

Fill both blanks to create a dictionary from two lists using zip() and a dictionary comprehension.

Python

keys = ['name', 'age', 'city']
values = ['Alice', 30, 'New York']
info = [1]([2] for [2] in zip(keys, values))
print(info)

Drag options to blanks, or click blank then click option'

Adict

Bitem

Citems

Dlist

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'list' instead of 'dict' creates a list of tuples, not a dictionary.

Using 'items' instead of 'item' causes a NameError because the variable is undefined.

The zip(keys, values) pairs keys and values. The dictionary constructor dict() creates a dictionary from these pairs. The variable item represents each pair in the comprehension.

5fill in blank

hard

Fill all three blanks to filter pairs from two lists where the number is greater than 2 using zip() and a dictionary comprehension.

Python

nums = [1, 2, 3, 4]
letters = ['a', 'b', 'c', 'd']
filtered = [1]([2]: [3] for [2], letter in zip(nums, letters) if [2] > 2)
print(filtered)

Drag options to blanks, or click blank then click option'

Adict

Bnum

Cletter

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'item' instead of 'num' or 'letter' causes confusion and errors.

Not using dict() results in a generator object, not a dictionary.

The dictionary comprehension creates a dictionary from pairs where the number is greater than 2. num is the variable for numbers, letter for letters, and dict() builds the dictionary.

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