Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!eu.feeder.erje.net!xlned.com!feeder3.xlned.com!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
MIME-Version: 1.0
In-Reply-To: <CAJ2vgs5uzr1BHF-koYmb5s0tBSkzChTKSQ8k=pCkVC21LWXoAQ@mail.gmail.com>
References: <CAJ2vgs5uzr1BHF-koYmb5s0tBSkzChTKSQ8k=pCkVC21LWXoAQ@mail.gmail.com>
From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Tue, 19 Feb 2013 14:10:42 -0700
Subject: Re: Verification of bank number using modulus 11
To: Python <python-list@python.org>
Content-Type: text/plain; charset=ISO-8859-1
Precedence: list
Newsgroups: comp.lang.python
Message-ID: <mailman.2063.1361308285.2939.python-list@python.org>
Lines: 29
NNTP-Posting-Host: 2001:888:2000:d::a6
Xref: csiph.com comp.lang.python:39277

On Tue, Feb 19, 2013 at 1:50 PM, Morten Engvoldsen <mortenengv@gmail.com> wrote:
> Here is my code:
>  def calc_checkdigit(isbn):
>         isbn = isbn.replace(".", "")
>         check_digit = int(isbn[-1])
>         isbn = isbn[:-1]
>         if len(isbn) != 10:
>                return False
>         result = sum((10 - i) * (int(x) if x != 'X' else 10) for i, x in
> enumerate(isbn))
>         return (result % 11) == check_digit
>
> calc_checkdigit(""8601.11.17947"")
>
> In my program : it is calculating 10 digit with weights 10-1, but according
> to above algorithm the weights should be : 5, 4, 3, 2, 7, 6, 5, 4, 3, 2.
>
> Could you please let me know how can i calculate the 10 digit with weights
> 5, 4, 3, 2, 7, 6, 5, 4, 3, 2. I am using python 2.7.

Use zip with the weight sequence instead of enumerate:

    weights = [5, 4, 3, 2, 7, 6, 5, 4, 3, 2]
    result = sum(w * (int(x) if x != 'X' else 10) for w, x in
zip(weights, isbn))

Do the account numbers actually use 'X', or is that just left over
from the ISBN algorithm?  If not, then you could replace "(int(x) if x
!= 'X' else 10)" with just "int(x)".