Lambda with map() in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of lambda with map() on a list

What is the output of this Python code?

Python

numbers = [1, 2, 3, 4]
result = list(map(lambda x: x * 3, numbers))
print(result)

A [1, 4, 9, 16]

B [1, 2, 3, 4]

C [3, 6, 9, 12]

D TypeError

💡 Hint

Remember map applies the function to each item in the list.

The lambda multiplies each number by 3, so the output list is each original number times 3.

❓ Predict Output

intermediate

Result of map with lambda and filter logic

What is the output of this code snippet?

Python

values = [0, 1, 2, 3, 4]
result = list(map(lambda x: x if x % 2 == 0 else 0, values))
print(result)

A SyntaxError

B [0, 1, 2, 3, 4]

C [0, 1, 0, 3, 0]

D [0, 0, 2, 0, 4]

💡 Hint

The lambda replaces odd numbers with zero.

For each number, if it is even, keep it; if odd, replace with 0. So 1 and 3 become 0.

❓ Predict Output

advanced

Output of nested lambda with map on strings

What does this code print?

Python

words = ['apple', 'banana', 'cherry']
result = list(map(lambda w: list(map(lambda c: c.upper(), w)), words))
print(result)

A ['APPLE', 'BANANA', 'CHERRY']

B [['A', 'P', 'P', 'L', 'E'], ['B', 'A', 'N', 'A', 'N', 'A'], ['C', 'H', 'E', 'R', 'R', 'Y']]

C [['apple'], ['banana'], ['cherry']]

D TypeError

💡 Hint

The inner map converts each character to uppercase.

Each word is mapped to a list of its uppercase letters, so the result is a list of lists of uppercase letters.

❓ Predict Output

advanced

Output of map with lambda and multiple iterables

What is the output of this code?

Python

a = [1, 2, 3]
b = [4, 5, 6]
result = list(map(lambda x, y: x + y, a, b))
print(result)

A [5, 7, 9]

B [1, 2, 3, 4, 5, 6]

C [4, 10, 18]

D TypeError

💡 Hint

map applies the lambda to pairs of elements from both lists.

The lambda adds corresponding elements: 1+4=5, 2+5=7, 3+6=9.

🧠 Conceptual

expert

Error raised by incorrect lambda syntax in map

What error does this code raise?

Python

result = list(map(lambda x: x * 2 if x > 2 for x in range(5)))

A SyntaxError

B TypeError

C NameError

D No error, outputs [6, 8]

💡 Hint

Check the lambda syntax and how map is used.

The lambda expression is invalid because it mixes a conditional expression with a for loop inside lambda, causing SyntaxError.