List Comprehension in Python — Python Technical Interview Questions & Answers

List Comprehension in Python

List Comprehension in Python

  • List comprehension builds a new list in one expression. Shape: [n * n for n in nums if n % 2 == 1]. Same result as a for-loop plus append, shorter when the idea is simple. squares = [x * x for x in range(5)] → [0, 1, 4, 9, 16]. Optional if filters items.
  • Don’t nest three comprehensions. If you cannot say it in one breath, use a loop. Write the comprehension and the equivalent for-loop in the viva — same output, two styles.
  • List Comprehension in Python — output: [1, 9, 25]. Odds 1,3,5 squared.
  nums = [1, 2, 3, 4, 5]
         │ n*n if odd
         ▼
      [1, 9, 25]

Technical Interview Tip: Comprehension vs loop — same result.

Code Examples for List Comprehension in Python

Example

# List comprehension
nums = [1, 2, 3, 4, 5]
print([n * n for n in nums if n % 2 == 1])

List Comprehension in Python — output: [1, 9, 25]. Odds 1,3,5 squared.

How to Explain List Comprehension in Python to an Interviewer

Explain List Comprehension as if you are teaching a junior — definition, then one tiny script.

[expr for x in seq if cond]. Builds a new list.

What does the example print, and why?

List Comprehension in Python — output: [1, 9, 25]

What mistake do freshers make with List Comprehension?

Over-nested comprehensions.