2018-03-06 16:51 GMT+03:00 Chris Angelico <ros...@gmail.com>: > On Wed, Mar 7, 2018 at 12:23 AM, Kirill Balunov <kirillbalu...@gmail.com> > wrote: > > Filter is generally faster than list comprehension or generators. > > > > %timeit [*filter(lambda x: x % 3, range(1000))] > > 100 µs ± 16.4 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each) > > > > f = lambda x: x % 3 > > > > %timeit [*(f(i) for i in range(1000))] > > 132 µs ± 73.5 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each) > > > > %timeit [f(i) for i in range(1000)] > > 107 µs ± 179 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each) > > > > These don't do the same thing, though. A more comparable comprehension is: > > [i for i in range(1000) if i % 3] > > rosuav@sikorsky:~$ python3 -m timeit '[i for i in range(1000) if i % 3]' > 10000 loops, best of 5: 34.5 usec per loop > rosuav@sikorsky:~$ python3 -m timeit '[*filter(lambda x: x % 3, > range(1000))]' > 5000 loops, best of 5: 81.1 usec per loop > > And my point about comprehensions was that you do NOT use a pointless > function for them - you just have inline code. If there is a > pre-existing function, sure! Use it. But when you use filter or map > with a lambda function, you should probably use a comprehension > instead. > > ChrisA > -- > https://mail.python.org/mailman/listinfo/python-list >
Thank you, I did not understand you at first, now everything is clear. In this sense of `x % 3`, I fully agree with you. With kind regards, -gdg -- https://mail.python.org/mailman/listinfo/python-list
