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Re: Comprehension with two variables - explanation needed

References <mailman.16184.1416754678.18130.python-list@python.org> <d1194d28-e9ed-4bd3-86e9-899e13a17097@googlegroups.com> <002501d00733$6995dce0$3cc196a0$@gmail.com>
Date 2014-11-24 02:42 +1100
Subject Re: Comprehension with two variables - explanation needed
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.16189.1416757339.18130.python-list@python.org> (permalink)

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On Mon, Nov 24, 2014 at 2:37 AM, Ivan Evstegneev
<webmailgroups@gmail.com> wrote:
> As I know from books and googling, the comps main idea looks approximately
> like this:
>
> [target <--main loop<--nested loop/s (and maybe some conditions)]    Am I
> right?
>
> But your code looks somehow inverted to me o_0
>
> Like:
>
> [[target with nested  loop] <--- main loop with initial values for target]

Your analysis is correct, and it's because of the bracketing. Just as
you learned back in maths class (or math class, if you're that sort),
you start from the innermost brackets and work your way out. In fact,
the nested example starts with the main loop, and for each value it
goes through, it creates the entire inner comprehension.

ChrisA

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Thread

Comprehension with two variables - explanation needed "Ivan Evstegneev" <webmailgroups@gmail.com> - 2014-11-23 16:56 +0200
  Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 07:09 -0800
    RE: Comprehension with two variables - explanation needed "Ivan Evstegneev" <webmailgroups@gmail.com> - 2014-11-23 17:37 +0200
    Re: Comprehension with two variables - explanation needed Chris Angelico <rosuav@gmail.com> - 2014-11-24 02:42 +1100
    RE: Comprehension with two variables - explanation needed Skip Montanaro <skip.montanaro@gmail.com> - 2014-11-23 09:45 -0600
      Re: Comprehension with two variables - explanation needed Roy Smith <roy@panix.com> - 2014-11-23 10:57 -0500
        Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 08:45 -0800
          Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 09:17 -0800
          RE: Comprehension with two variables - explanation needed "Ivan Evstegneev" <webmailgroups@gmail.com> - 2014-11-23 19:27 +0200
          Re: Comprehension with two variables - explanation needed Steven D'Aprano <steve@pearwood.info> - 2014-11-24 04:42 +0000
            Re: Comprehension with two variables - explanation needed Chris Angelico <rosuav@gmail.com> - 2014-11-24 15:51 +1100
              Re: Comprehension with two variables - explanation needed Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-25 09:20 +1100
            Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 22:47 -0800
            Re: Comprehension with two variables - explanation needed Dan Stromberg <drsalists@gmail.com> - 2014-11-24 16:42 -0800
        Re: Comprehension with two variables - explanation needed Skip Montanaro <skip.montanaro@gmail.com> - 2014-11-23 10:45 -0600
        Re: Comprehension with two variables - explanation needed Roy Smith <roy@panix.com> - 2014-11-23 12:08 -0500
        Re: Comprehension with two variables - explanation needed Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2014-11-23 17:46 +0000

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