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Date: Wed, 14 Mar 2012 23:54:31 +0000
Subject: Re: Python is readable
From: Arnaud Delobelle <arnodel@gmail.com>
To: Kiuhnm <kiuhnm03.4t.yahoo.it@mail.python.org>
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On 14 March 2012 23:34, Kiuhnm <kiuhnm03.4t.yahoo.it@mail.python.org> wrote=
:
> I've just started to read
> =C2=A0The Quick Python Book (2nd ed.)
> The author claims that Python code is more readable than Perl code and
> provides this example:
>
> --- Perl ---
> sub pairwise_sum {
> =C2=A0 =C2=A0my($arg1, $arg2) =3D @_;
> =C2=A0 =C2=A0my(@result) =3D ();
> =C2=A0 =C2=A0@list1 =3D @$arg1;
> =C2=A0 =C2=A0@list2 =3D @$arg2;
> =C2=A0 =C2=A0for($i=3D0; $i < length(@list1); $i++) {
> =C2=A0 =C2=A0 =C2=A0 =C2=A0push(@result, $list1[$i] + $list2[$i]);
> =C2=A0 =C2=A0}
> =C2=A0 =C2=A0return(\@result);
> }
>
> --- Python ---
> def pairwise_sum(list1, list2):
> =C2=A0 =C2=A0result =3D []
> =C2=A0 =C2=A0for i in range(len(list1)):
> =C2=A0 =C2=A0 =C2=A0 =C2=A0result.append(list1[i] + list2[i])
> =C2=A0 =C2=A0return result
> --- ---
>
> It's quite clear that he knows little about Perl.
> Here's what I would've written:
>
> sub pairwise_sum {
> =C2=A0 =C2=A0my ($list1, $list2) =3D @_;
> =C2=A0 =C2=A0my @result;
> =C2=A0 =C2=A0push @result, $list1->[$_] + $list2->[$_] for (0..@$list1-1)=
;
> =C2=A0 =C2=A0\@result;
> }
>
> Having said that, the Python code is still more readable, so there's no n=
eed
> to misrepresent Perl that way.
> Now I'm wondering whether the author will show me "good" or "bad" Python
> code throughout the book. Should I keep reading?

I don't know this book and there may be a pedagogical reason for the
implementation you quote, but pairwise_sum is probably better
implemented in Python 3.X as:

def pairwise_sum(list1, list2):
    return [x1 + x2 for x1, x2 in zip(list1, list2)]

Or in Python 2.X:

from itertools import izip

def pairwise_sum(list1, list2):
    return [x1 + x2 for x1, x2 in izip(list1, list2)]

Or even:

from operator import add

def pairwise_sum(list1, list2):
    return map(add, list1, list2)

--=20
Arnaud