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
|
# issn.py - functions for handling ISSNs
#
# Copyright (C) 2010, 2011, 2012 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. It has a checksum similar to ISBN-10.
>>> is_valid('0024-9319')
True
>>> is_valid('0032147X') # incorrect check digit
False
>>> compact('0032-1478')
'00321478'
>>> format('00249319')
'0024-9319'
>>> to_ean('0264-3596')
'9770264359008'
"""
from stdnum import ean
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 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:
number = compact(number)
except:
return False
return len(number) == 8 and \
number[:-1].isdigit() and \
calc_check_digit(number[:-1]) == number[-1]
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. The number is assumed to be a
valid ISSN."""
number = '977' + compact(number)[:-1] + issue_code
return number + ean.calc_check_digit(number)
|