Python List Comprehensions and Generators Flashcards
6 cards from real Python practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Python List Comprehensions and Generators flashcards as text
What is the output of `[x**2 for x in range(4)]`?
Answer: [0, 1, 4, 9]
range(4) produces 0, 1, 2, 3, and squaring each gives [0, 1, 4, 9].
Which syntax creates a generator expression in Python?
Answer: (x for x in range(10))
Parentheses around a comprehension-style expression create a generator, not a list.
What does the `yield` keyword do in a Python function?
Answer: Pauses execution and returns a value to the caller, resuming on next call
yield turns a function into a generator, pausing at each yield and resuming from that point when next() is called.
What is the output of `list(x for x in range(5) if x % 2 == 0)`?
Answer: [0, 2, 4]
The condition x % 2 == 0 filters to even numbers 0, 2, and 4 from range(5).
Which of the following creates a set comprehension?
Answer: {x*2 for x in range(5)}
Curly braces with a single expression and no colon create a set comprehension.
What is the memory advantage of using a generator over a list?
Answer: Generators produce values one at a time, using constant memory
Generators yield values lazily one at a time, so they never hold the entire sequence in memory.