Set creation in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of set creation with duplicates

What is the output of this Python code?

my_set = {1, 2, 2, 3, 4, 4, 4}
print(my_set)

Python

my_set = {1, 2, 2, 3, 4, 4, 4}
print(my_set)

A {1, 2, 3, 4}

B {1, 2, 2, 3, 4, 4, 4}

C [1, 2, 3, 4]

D (1, 2, 3, 4)

💡 Hint

Remember that sets do not keep duplicates.

Sets automatically remove duplicate values, so only unique elements remain.

❓ Predict Output

intermediate

Creating a set from a list

What will be printed by this code?

my_list = [5, 6, 7, 5, 6]
my_set = set(my_list)
print(my_set)

Python

my_list = [5, 6, 7, 5, 6]
my_set = set(my_list)
print(my_set)

A (5, 6, 7)

B [5, 6, 7, 5, 6]

C {5, 6, 7}

D {5, 6, 7, 5, 6}

💡 Hint

Converting a list to a set removes duplicates.

The set constructor removes duplicates and keeps unique elements only.

❓ Predict Output

advanced

Set comprehension with condition

What is the output of this code?

result = {x * x for x in range(5) if x % 2 == 0}
print(result)

Python

result = {x * x for x in range(5) if x % 2 == 0}
print(result)

A {0, 2, 4, 6, 8}

B {1, 9, 25}

C {0, 1, 4, 9, 16}

D {0, 4, 16}

💡 Hint

Only even numbers from 0 to 4 are squared.

The comprehension squares only even numbers: 0, 2, 4 → 0, 4, 16.

❓ Predict Output

advanced

Set creation with mutable elements

What error does this code raise?

my_set = {1, 2, [3, 4]}

Python

my_set = {1, 2, [3, 4]}

A TypeError

B SyntaxError

C ValueError

D No error, set created

💡 Hint

Sets cannot contain mutable elements like lists.

Lists are mutable and cannot be added to sets, causing a TypeError.

🧠 Conceptual

expert

Number of items in a set after complex creation

How many items are in the set after running this code?

data = [1, 2, 2, 3, 4, 4, 5]
result = {x for x in data if x % 2 != 0}
print(len(result))

Python

data = [1, 2, 2, 3, 4, 4, 5]
result = {x for x in data if x % 2 != 0}
print(len(result))

A 7

B 3

C 4

D 5

💡 Hint

Count unique odd numbers in the list.

Odd numbers are 1, 3, 5. They are unique, so length is 3.