/usr/lib/python2.7/dist-packages/stdnum/issn.py is in python-stdnum 1.5-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 | # issn.py - functions for handling ISSNs
#
# Copyright (C) 2010-2015 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""ISSN (International Standard Serial Number).
The ISSN (International Standard Serial Number) is the standard code to
identify periodical publications (e.g. magazines).
An ISSN has 8 digits and is formatted in two pairs of 4 digits separated by a
hyphen. The last digit is a check digit and may be 0-9 or X (similar to
ISBN-10).
More information:
* https://en.wikipedia.org/wiki/International_Standard_Serial_Number
* http://www.issn.org/
>>> validate('0024-9319')
'00249319'
>>> validate('0032147X')
Traceback (most recent call last):
...
InvalidChecksum: ...
>>> validate('003214712')
Traceback (most recent call last):
...
InvalidLength: ...
>>> compact('0032-1478')
'00321478'
>>> format('00249319')
'0024-9319'
>>> to_ean('0264-3596')
'9770264359008'
"""
from stdnum import ean
from stdnum.exceptions import *
from stdnum.util import clean
def compact(number):
"""Convert the ISSN to the minimal representation. This strips the number
of any valid ISSN separators and removes surrounding whitespace."""
return clean(number, ' -').strip().upper()
def calc_check_digit(number):
"""Calculate the ISSN check digit for 10-digit numbers. The number passed
should not have the check bit included."""
check = (11 - sum((8 - i) * int(n)
for i, n in enumerate(number))) % 11
return 'X' if check == 10 else str(check)
def validate(number):
"""Checks to see if the number provided is a valid ISSN. This checks
the length and whether the check digit is correct."""
number = compact(number)
if not number[:-1].isdigit():
raise InvalidFormat()
if len(number) != 8:
raise InvalidLength()
if calc_check_digit(number[:-1]) != number[-1]:
raise InvalidChecksum()
return number
def is_valid(number):
"""Checks to see if the number provided is a valid ISSN. This checks
the length and whether the check digit is correct."""
try:
return bool(validate(number))
except ValidationError:
return False
def format(number):
"""Reformat the passed number to the standard format."""
number = compact(number)
return number[:4] + '-' + number[4:]
def to_ean(number, issue_code='00'):
"""Convert the number to EAN-13 format."""
number = '977' + validate(number)[:-1] + issue_code
return number + ean.calc_check_digit(number)
|