Difference and symmetric difference in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the difference between set_a and set_b.

Python

set_a = {1, 2, 3, 4}
set_b = {3, 4, 5, 6}
difference = set_a.[1](set_b)
print(difference)

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

Aunion

Bsymmetric_difference

Cintersection

Ddifference

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'union' instead of 'difference' returns all elements from both sets.

Using 'intersection' returns only common elements.

The difference method returns elements in set_a that are not in set_b.

2fill in blank

medium

Complete the code to find the symmetric difference between set_x and set_y.

Python

set_x = {10, 20, 30}
set_y = {20, 40, 50}
sym_diff = set_x.[1](set_y)
print(sym_diff)

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

Adifference

Bsymmetric_difference

Cintersection

Dunion

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'difference' returns elements only from the first set.

Using 'union' returns all elements from both sets.

The symmetric_difference method returns elements in either set but not in both.

3fill in blank

hard

Fix the error in the code to correctly find the difference of set_m and set_n.

Python

set_m = {7, 8, 9}
set_n = {8, 10}
diff = set_m.[1](set_n)
print(diff)

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

Adiffrence

Bsymmetric_difference

Cdifference

Dintersect

Attempts:

3 left

💡 Hint

Common Mistakes

Misspelling 'difference' causes AttributeError.

Using 'intersect' instead of 'intersection' causes error.

The correct method name is difference. Misspelled names cause errors.

4fill in blank

hard

Fill both blanks to create a dictionary with words as keys and their lengths as values, only for words longer than 3 letters.

Python

words = ['apple', 'bat', 'carrot', 'dog']
lengths = {word: [1] for word in words if len(word) [2] 3}
print(lengths)

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

Alen(word)

B<=

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' includes shorter words.

Using 'word' as value stores the word, not its length.

Use len(word) to get length and > to filter words longer than 3 letters.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase words as keys and their lengths as values, only for words with length greater than 4.

Python

words = ['tree', 'house', 'car', 'elephant']
result = { [1]: [2] for word in words if len(word) [3] 4 }
print(result)

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

Aword.upper()

Blen(word)

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'word' as key keeps original case.

Using '<' or '<=' includes shorter words.

Keys are uppercase words (word.upper()), values are lengths (len(word)), filtered by length > 4.

Practice

1. What does the difference operation A - B return when applied to two sets A and B?

easy

A. All elements from both A and B

B. Elements in B but not in A

C. Elements in A but not in B

D. Elements common to both A and B

Solution

1. Step 1: Understand the difference operation

   The difference A - B means all elements that are in A but not in B.

2. Step 2: Compare options with definition

   Elements in A but not in B matches this definition exactly, others describe different set operations.

3. Final Answer:

   Elements in A but not in B -> Option C

4. Quick Check:

   Difference = Elements only in first set [OK]

Hint: Difference = items only in the first set [OK]

Common Mistakes:

• Confusing difference with symmetric difference
• Thinking difference includes elements from both sets
• Mixing up order of sets in difference

2. Which of the following is the correct syntax to find the symmetric difference between two sets A and B in Python?

easy

A. A ^ B

B. A - B

C. A | B

D. A & B

Solution

1. Step 1: Recall symmetric difference operator

   In Python, symmetric difference between sets is found using the ^ operator.

2. Step 2: Match operators to meanings

   - is difference, | is union, & is intersection, so only ^ is correct for symmetric difference.

3. Final Answer:

   A ^ B -> Option A

4. Quick Check:

   Symmetric difference uses ^ operator [OK]

Hint: Use ^ for symmetric difference in Python [OK]

Common Mistakes:

• Using - instead of ^ for symmetric difference
• Confusing union (|) with symmetric difference
• Using & which is intersection, not symmetric difference

3. What is the output of the following code?

 A = {1, 2, 3, 4} 
 B = {3, 4, 5, 6} 
 print(A - B) 

medium

A. {3, 4}

B. {1, 2}

C. {5, 6}

D. {1, 2, 3, 4, 5, 6}

Solution

1. Step 1: Calculate difference A - B

   Elements in A are {1, 2, 3, 4}, in B are {3, 4, 5, 6}. Difference A - B is elements in A not in B, which are {1, 2}.

2. Step 2: Verify output matches options

   {1, 2} is {1, 2}, which matches the calculated difference.

3. Final Answer:

   {1, 2} -> Option B

4. Quick Check:

   A - B = {1, 2} [OK]

Hint: Difference removes items found in second set [OK]

Common Mistakes:

• Including elements common to both sets
• Confusing difference with union
• Swapping sets order in difference

4. The following code is intended to print the symmetric difference of sets A and B. What is the error?

 A = {1, 2, 3} 
 B = {2, 3, 4} 
 print(A -^ B) 

medium

A. Prints the union of A and B

B. Prints the difference of A and B

C. Prints the intersection of A and B

D. SyntaxError due to invalid operator '-^'

Solution

1. Step 1: Identify the operator used

   The code uses -^ which is not a valid Python operator.

2. Step 2: Understand correct symmetric difference syntax

   Symmetric difference uses ^ alone, not combined with -. So this causes a syntax error.

3. Final Answer:

   SyntaxError due to invalid operator '-^' -> Option D

4. Quick Check:

   Invalid operator causes SyntaxError [OK]

Hint: Use ^ alone for symmetric difference, no combined operators [OK]

Common Mistakes:

• Combining - and ^ operators incorrectly
• Trying to use -^ as a single operator
• Not recognizing syntax errors from invalid operators

5. Given two sets A = {1, 2, 3, 4, 5} and B = {4, 5, 6, 7}, which expression returns a set of elements that are in either A or B but not in both, and also excludes the element 7 if present?

hard

A. (A ^ B) - {7}

B. (A - B) | (B - A) | {7}

C. (A | B) - {7}

D. (A & B) - {7}

Solution

1. Step 1: Understand symmetric difference and exclusion

   Symmetric difference A ^ B gives elements in either set but not both. To exclude 7, subtract {7}.

2. Step 2: Analyze options

   (A ^ B) - {7} correctly computes symmetric difference then removes 7. (A - B) | (B - A) | {7} incorrectly adds {7}. (A | B) - {7} is union minus 7, which includes common elements. (A & B) - {7} is intersection minus 7, which is wrong.

3. Final Answer:

   (A ^ B) - {7} -> Option A

4. Quick Check:

   Symmetric difference minus {7} = (A ^ B) - {7} [OK]

Hint: Subtract {7} after symmetric difference to exclude it [OK]

Common Mistakes:

• Using union instead of symmetric difference
• Adding {7} instead of subtracting
• Using intersection which is common elements only