Re: Pythonic infinite for loop?

From	Paul Rubin <no.email@nospam.invalid>
Newsgroups	comp.lang.python
Subject	Re: Pythonic infinite for loop?
References	<mailman.377.1302833455.9059.python-list@python.org>
Date	2011-04-15 00:24 -0700
Message-ID	<7xsjtkx9hy.fsf@ruckus.brouhaha.com> (permalink)
Organization	Nightsong/Fort GNOX

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Chris Angelico <rosuav@gmail.com> writes:
That loop will exit at the first gap in the sequence.  If that's what
you want, you could try (untested):

   from itertools import takewhile

   seq = takewhile(lambda n: ('Keyword%d'%n) in dct, count(1))
   lst = map(dct.get, seq)

This does 2 lookups per key, which you could avoid by making the code
uglier (untested):

   sentinel = object()
   seq = (dct.get('Keyword%d'%i,sentinel) for i in count(1))
   lst = list(takewhile(lambda x: x != sentinel, seq))

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Pythonic infinite for loop? Chris Angelico <rosuav@gmail.com> - 2011-04-15 12:10 +1000
  Re: Pythonic infinite for loop? Nobody <nobody@nowhere.com> - 2011-04-15 03:33 +0100
  Re: Pythonic infinite for loop? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-15 02:33 +0000
    Re: Pythonic infinite for loop? Chris Angelico <rosuav@gmail.com> - 2011-04-15 13:58 +1000
      Re: Pythonic infinite for loop? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-15 12:52 +0000
        Re: Pythonic infinite for loop? Roy Smith <roy@panix.com> - 2011-04-15 09:13 -0400
        Re: Pythonic infinite for loop? Chris Angelico <rosuav@gmail.com> - 2011-04-16 01:35 +1000
          Re: Pythonic infinite for loop? Paul Rubin <no.email@nospam.invalid> - 2011-04-15 09:10 -0700
  Re: Pythonic infinite for loop? Paul Rubin <no.email@nospam.invalid> - 2011-04-15 00:24 -0700
    Re: Pythonic infinite for loop? Chris Angelico <rosuav@gmail.com> - 2011-04-15 17:35 +1000
      Re: Pythonic infinite for loop? Paul Rubin <no.email@nospam.invalid> - 2011-04-15 00:47 -0700
        Re: Pythonic infinite for loop? Peter Otten <__peter__@web.de> - 2011-04-15 10:11 +0200
  Re: Pythonic infinite for loop? Peter Otten <__peter__@web.de> - 2011-04-15 10:25 +0200
    Re: Pythonic infinite for loop? Chris Angelico <rosuav@gmail.com> - 2011-04-15 18:32 +1000
      Re: Pythonic infinite for loop? Peter Otten <__peter__@web.de> - 2011-04-15 11:32 +0200
      Re: Pythonic infinite for loop? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-15 12:48 +0000

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