[Python-ideas] while conditional in list comprehension ??

Chris Angelico rosuav at gmail.com
Mon Jan 28 14:55:42 CET 2013


On Tue, Jan 29, 2013 at 12:33 AM, Wolfgang Maier
<wolfgang.maier at biologie.uni-freiburg.de> wrote:
> Why not extend this filtering by allowing a while statement in addition to
> if, as in:
>
> [n for n in range(1,1000) while n < 400]

The time machine strikes again! Check out itertools.takewhile - it can
do pretty much that:

import itertools
[n for n in itertools.takewhile(lambda n: n<400, range(1,1000))]

It's not quite list comp notation, but it works.

>>> [n for n in itertools.takewhile(lambda n: n<40, range(1,100))]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
37, 38, 39]

ChrisA



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