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Re: Understanding Python Code

References <4045d8ca-923d-4384-a684-57cbd80ab7b7@googlegroups.com>
From Ian Kelly <ian.g.kelly@gmail.com>
Date 2014-06-18 13:15 -0600
Subject Re: Understanding Python Code
Newsgroups comp.lang.python
Message-ID <mailman.11118.1403118997.18130.python-list@python.org> (permalink)

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On Wed, Jun 18, 2014 at 10:36 AM,  <subhabangalore@gmail.com> wrote:
> The questions are,
> i) prev_f_sum = sum(f_prev[k]*a[k][st] for k in states)
> here f_prev is called,
> f_prev is assigned to  f_curr ["f_prev = f_curr"]
> f_curr[st]  is again being calculated as, ["f_curr[st] = e[st][x_i] * prev_f_sum"] which again calls "prev_f_sum"
>
> I am slightly confused which one would be first calculated and how to proceed next?

These things that you describe as "calls" are not calls.  f_prev and
f_curr are data structures (in this case dicts), not functions.
Accessing "f_prev[k]" does not call f_prev or in any way cause
f_prev[k] to be computed; it just looks up what value is recorded in
the f_prev dict for the key k.

Python is an imperative language, not declarative.  If you want to
know what order these things are calculated in, just follow the
program flow.

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Thread

Understanding Python Code subhabangalore@gmail.com - 2014-06-18 09:36 -0700
  Re: Understanding Python Code Ian Kelly <ian.g.kelly@gmail.com> - 2014-06-18 13:15 -0600
    Re: Understanding Python Code subhabangalore@gmail.com - 2014-06-18 22:50 -0700
      Re: Understanding Python Code Ian Kelly <ian.g.kelly@gmail.com> - 2014-06-19 01:00 -0600
        Re: Understanding Python Code subhabangalore@gmail.com - 2014-06-19 02:48 -0700
          Re: Understanding Python Code Ian Kelly <ian.g.kelly@gmail.com> - 2014-06-19 08:09 -0600
            Re: Understanding Python Code subhabangalore@gmail.com - 2014-06-19 07:27 -0700
              Re: Understanding Python Code subhabangalore@gmail.com - 2014-06-19 11:44 -0700
                Re: Understanding Python Code Ian Kelly <ian.g.kelly@gmail.com> - 2014-06-19 13:07 -0600
                Understanding Python Code[Forward_Backward_Wikipedia] subhabangalore@gmail.com - 2014-06-21 15:05 -0700

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