Set creation in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a set with the numbers 1, 2, and 3.

Python

my_set = [1]

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

A(1, 2, 3)

B[1, 2, 3]

C{1, 2, 3}

D"1, 2, 3"

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets [] creates a list, not a set.

Using parentheses () creates a tuple, not a set.

The curly braces {} create a set in Python. So {1, 2, 3} is a set with numbers 1, 2, and 3.

2fill in blank

medium

Complete the code to create an empty set.

Python

empty_set = [1]

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

A{}

Bset()

C[]

Dempty()

Attempts:

3 left

💡 Hint

Common Mistakes

Using {} creates an empty dictionary, not a set.

Using [] creates an empty list, not a set.

Using set() creates an empty set. Curly braces {} create an empty dictionary, not a set.

3fill in blank

hard

Fix the error in the code to create a set from a list.

Python

numbers = [1, 2, 3, 4]
my_set = [1]

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

A(numbers)

B{numbers}

C[numbers]

Dset(numbers)

Attempts:

3 left

💡 Hint

Common Mistakes

Using {numbers} tries to put the whole list inside a set, causing an error.

Using square or round brackets does not create a set.

The set() function converts a list into a set. Using curly braces around the list creates a set with one element (the list itself), which is not allowed because lists are unhashable.

4fill in blank

hard

Complete the code to create a set of squares for numbers 1 to 5.

Python

squares = { x**2 for x in range(1, 6) if x [1] 3 }

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

A{

B[

C>

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets creates a list, not a set.

Using the wrong comparison operator changes the filtered numbers.

The code creates a set of squares for numbers greater than 3. Curly braces with an expression create a set comprehension. The condition x > 3 filters numbers greater than 3.

5fill in blank

hard

Fill both blanks to create a set of uppercase letters from a list, filtering only letters after 'm'.

Python

letters = ['a', 'b', 'm', 'n', 'z']
result = [ letter for letter in letters if letter [1] 'm' ]
result = {x[2] for x in result}

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

A{letter.upper()}

B>

C.upper()

D[

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces in the first line creates a set, not a list.

Using the wrong comparison operator filters wrong letters.

Forgetting to convert letters to uppercase.

The first line creates a list of letters after 'm'. The second line uses a set comprehension to convert each letter to uppercase. The .upper() method changes letters to uppercase.

Practice

1. Which of the following is the correct way to create a set with the elements 1, 2, and 3 in Python?

easy

A. (1, 2, 3)

B. [1, 2, 3]

C. {1, 2, 3}

D. set[1, 2, 3]

Solution

1. Step 1: Understand set creation syntax

   Sets are created using curly braces with comma-separated values or the set() function.

2. Step 2: Identify correct syntax for set with elements

   {1, 2, 3} correctly creates a set with elements 1, 2, and 3.

3. Final Answer:

   {1, 2, 3} -> Option C

4. Quick Check:

   Curly braces with values = set [OK]

Hint: Use curly braces with commas for sets, not brackets [OK]

Common Mistakes:

• Using square brackets creates a list, not a set
• Using parentheses creates a tuple, not a set
• Using set[] is invalid syntax

2. What is the correct way to create an empty set in Python?

easy

A. set()

B. {}

C. []

D. empty_set()

Solution

1. Step 1: Recognize empty set syntax

   Using {} creates an empty dictionary, not a set.

2. Step 2: Use the set() function for empty sets

   set() correctly creates an empty set.

3. Final Answer:

   set() -> Option A

4. Quick Check:

   Empty set = set() function [OK]

Hint: Empty sets need set(), not curly braces [OK]

Common Mistakes:

• Using {} creates an empty dictionary, not a set
• Using [] creates an empty list
• Using undefined functions like empty_set()

3. What will be the output of the following code?

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

medium

A. {1, 2, 2, 3, 4, 4}

B. [1, 2, 3, 4]

C. (1, 2, 3, 4)

D. {1, 2, 3, 4}

Solution

1. Step 1: Understand set uniqueness property

   Sets automatically remove duplicate elements, so repeated values appear only once.

2. Step 2: Apply uniqueness to given elements

   Duplicates 2 and 4 are removed, leaving {1, 2, 3, 4}.

3. Final Answer:

   {1, 2, 3, 4} -> Option D

4. Quick Check:

   Sets remove duplicates = {1, 2, 3, 4} [OK]

Hint: Sets keep unique items only, duplicates vanish [OK]

Common Mistakes:

• Expecting duplicates to remain in the set
• Confusing set output with list or tuple syntax
• Thinking sets preserve order

4. Identify the error in the following code snippet:

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

medium

A. SyntaxError due to incorrect set creation syntax

B. Prints {1, 2, 3} correctly

C. TypeError because set() expects a list

D. NameError because set is not defined

Solution

1. Step 1: Check set creation syntax

   The correct way to create a set using the function is set() with parentheses, not curly braces.

2. Step 2: Identify syntax error

   set{1, 2, 3} is invalid syntax and causes a SyntaxError.

3. Final Answer:

   SyntaxError due to incorrect set creation syntax -> Option A

4. Quick Check:

   Use set() with parentheses, not braces [OK]

Hint: Use parentheses with set(), not curly braces [OK]

Common Mistakes:

• Using curly braces after set instead of parentheses
• Confusing set() with dictionary syntax
• Assuming set is undefined

5. Given the list nums = [1, 2, 2, 3, 4, 4, 5], which code snippet correctly creates a set of unique elements from this list?

hard

A. unique_nums = {nums}

B. unique_nums = set(nums)

C. unique_nums = list(set(nums))

D. unique_nums = {1, 2, 3, 4, 5}

Solution

1. Step 1: Understand how to convert list to set

   The set() function can take an iterable like a list and return a set of unique elements.

2. Step 2: Analyze each option

   unique_nums = {nums} creates a set with the entire list as one element (invalid). unique_nums = set(nums) correctly converts the list to a set. unique_nums = list(set(nums)) converts to set then back to list, which is not a set. unique_nums = {1, 2, 3, 4, 5} manually writes the set but is not dynamic.

3. Final Answer:

   unique_nums = set(nums) -> Option B

4. Quick Check:

   Use set() on list to get unique elements [OK]

Hint: Use set() on list to get unique items fast [OK]

Common Mistakes:

• Trying to put list inside curly braces directly
• Converting set back to list when set is needed
• Hardcoding values instead of using the list variable