Dictionary comprehension with condition in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of dictionary comprehension with a simple condition

What is the output of this Python code?

Python

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

A {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}

B {1: 1, 3: 9}

C {0: 0, 2: 4, 4: 16}

D {}

💡 Hint

Remember, the condition filters keys where x is even.

The comprehension includes only keys where x % 2 == 0, so only 0, 2, and 4 are included with their squares.

❓ Predict Output

intermediate

Dictionary comprehension with else in value expression

What does this code print?

Python

result = {x: ('even' if x % 2 == 0 else 'odd') for x in range(3)}
print(result)

A {0: 'even', 1: 'odd', 2: 'even'}

B {0: 'odd', 1: 'even', 2: 'odd'}

C {0: 'even', 2: 'even'}

D {1: 'odd'}

💡 Hint

The value uses a conditional expression to label even or odd.

Each key from 0 to 2 is included. Values are 'even' if key is even, else 'odd'.

❓ Predict Output

advanced

Output of nested dictionary comprehension with condition

What is the output of this code?

Python

result = {x: {y: x*y for y in range(3) if y != x} for x in range(3)}
print(result)

A {0: {}, 1: {}, 2: {}}

B {0: {1: 1, 2: 2}, 1: {0: 0, 2: 2}, 2: {0: 0, 1: 1}}

C {0: {0: 0, 1: 0, 2: 0}, 1: {0: 0, 1: 1, 2: 2}, 2: {0: 0, 1: 2, 2: 4}}

D {0: {1: 0, 2: 0}, 1: {0: 0, 2: 2}, 2: {0: 0, 1: 2}}

💡 Hint

Inner comprehension excludes y equal to x.

For each x, inner dict includes y from 0 to 2 except y == x, mapping y to x*y.

❓ Predict Output

advanced

Dictionary comprehension with complex condition and filtering

What will be printed by this code?

Python

data = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
result = {k: v for k, v in data.items() if v % 2 == 0 and k != 'd'}
print(result)

A {'a': 1, 'c': 3}

B {'b': 2}

C {'b': 2, 'd': 4}

D {}

💡 Hint

Filter keys with even values but exclude key 'd'.

Only 'b' has an even value and key not equal to 'd', so only {'b': 2} remains.

🧠 Conceptual

expert

Count of items in dictionary comprehension with multiple conditions

How many items are in the dictionary created by this comprehension? {num: num**3 for num in range(10) if num % 2 == 1 if num > 5}

A 2

B 5

C 4

D 3

💡 Hint

Count numbers from 0 to 9 that are odd and greater than 5.

Numbers 7 and 9 satisfy both conditions, so the dictionary has 2 items.