filter() — Python Technical Interview Questions & Answers

filter()

filter()

  • filter() is built into Python. You do not import it. Freshers only need one honest call and the printed result — not a long definition.
  • filter() — output: [30]. Only values > 20.
  • Wrong type often raises TypeError. Empty values matter for bool/all/any. Don’t mix filter up with a similar name (sorted vs sort, int vs float).

Technical Interview Tip: Call filter() once and say what prints.

Code Examples for filter()

Example

# filter()
print(list(filter(lambda n: n > 20, [10, 30, 20])))

filter() — output: [30]. Only values > 20.

How to Explain filter() to an Interviewer

Explain filter() as if you are teaching a junior — definition, then one tiny script.

filter() is built-in — no import. One call + exact output.

What does the example print, and why?

filter() — output: [30]

What mistake do freshers make with filter()?

Wrong type → TypeError.