what's the difference between these two python functions

Question

today I had an interview and got a question that I answered wrong. Here's the question:

def gen():
    return [lambda x: x + i for i in range(4)]

print([m(1) for m in gen()])

The result is [4, 4, 4, 4]. My answer was [1, 2, 3, 4]. I also ran the following code.

def gen():
    return (lambda x: x + i for i in range(4))

print([m(1) for m in gen()])

The result is [1, 2, 3, 4]. Could anyone explain? I am so confused.

The first one has [ ] brackets and the second (). Using [ ] all the numbers are always set to the last value added. — Nathan, Apr 03 '18 at 15:32
@Nathan i was curious about the answer, could you make one with more details ? Also upvoted, found that interesting. — xoxel, Apr 03 '18 at 15:34
Good question and with good answer https://stackoverflow.com/questions/28268439/python-list-comprehension-with-lambdas — BENY, Apr 03 '18 at 15:35

score 0 · Answer 1 · answered Apr 03 '18 at 15:38

0

The second code snippet that uses () is a generator. Used to save memory

Look at PEP-289

answered Apr 03 '18 at 15:38

AB Abhi

1 Answers1