map() function in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of map() with lambda and list

What is the output of this Python code?

Python

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

A [1, 4, 9, 16]

B [1, 8, 27, 64]

C [2, 4, 6, 8]

D [1, 2, 3, 4]

💡 Hint

Think about what the lambda function does to each element.

The lambda function squares each number. So 1**2=1, 2**2=4, 3**2=9, 4**2=16.

❓ Predict Output

intermediate

map() with multiple iterables

What is the output of this code snippet?

Python

def add(x, y):
    return x + y

result = list(map(add, [1, 2, 3], [4, 5, 6]))
print(result)

A [5, 7, 9]

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

C [4, 5, 6]

D [1, 6, 9]

💡 Hint

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

The add function sums pairs: 1+4=5, 2+5=7, 3+6=9.

❓ Predict Output

advanced

map() with filter and string conversion

What is the output of this code?

Python

numbers = [10, 15, 20, 25]
result = list(map(str, filter(lambda x: x % 20 == 0, numbers)))
print(result)

A ['10', '15', '20', '25']

B ['10', '20']

C ['20']

D ['20', '25']

💡 Hint

filter keeps only numbers divisible by 20, then map converts them to strings.

Only 20 is divisible by 20, so filter returns [20]. map converts it to ['20'].

❓ Predict Output

advanced

map() with None as function argument

What is the output of this code?

Python

result = list(map(None, [1, 2, 3]))
print(result)

A []

B [1, 2, 3]

C [None, None, None]

D TypeError

💡 Hint

In Python 3, map() requires a callable function, None is not callable.

Passing None as the function causes a TypeError because None is not callable.

🧠 Conceptual

expert

Behavior of map() with infinite iterator

Consider this code: import itertools result = map(lambda x: x*2, itertools.count(1)) output = [] for i, val in enumerate(result): if i == 5: break output.append(val) print(output) What is the output printed?

A [0, 2, 4, 6, 8]

B [2, 4, 6, 8, 10]

C [1, 2, 3, 4, 5]

D Infinite loop, no output

💡 Hint

itertools.count(1) generates numbers starting at 1 endlessly; map doubles them; loop stops after 5 items.

The loop collects first 5 doubled numbers: 1*2=2, 2*2=4, 3*2=6, 4*2=8, 5*2=10.