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# __init__.py - functions for handling ISBNs
#
# Copyright (C) 2010 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
"""Module for handling ISBNs (International Standard Book Number). This
module handles both numbers in ISBN10 (10-digit) and ISBN13 (13-digit)
format.
>>> validate('978-9024538270')
True
>>> validate('978-9024538271') # incorrect check digit
False
>>> compact('1-85798-218-5')
'1857982185'
>>> format('9780471117094')
'978-0-471-11709-4'
>>> format('1857982185')
'1-85798-218-5'
>>> isbn_type('1-85798-218-5')
'ISBN10'
>>> isbn_type('978-0-471-11709-4')
'ISBN13'
>>> to_isbn13('1-85798-218-5')
'978-1-85798-218-3'
"""
def compact(number):
"""Convert the ISBN to the minimal representation. This strips the number
of any valid ISBN separators and removes surrounding whitespace."""
number = number.replace(' ','').replace('-','').strip().upper()
if len(number) == 9:
number = '0' + number
return number
def _calc_isbn10_check_digit(number):
"""Calculate the ISBN check digit for 10-digit numbers. The number passed
should not have the check bit included."""
check = sum( (i + 1) * int(number[i]) for i in range(len(number)) ) % 11
return 'X' if check == 10 else str(check)
def _calc_isbn13_check_digit(number):
"""Calculate the ISBN check digit for 13-digit numbers. The number passed
should not have the check bit included."""
return str((10 - sum( (2 * (i % 2) + 1) * int(number[i]) for i in range(len(number)))) % 10)
def isbn_type(number):
"""Check the passed number and returns 'ISBN13', 'ISBN10' or None (for
invalid) for checking the type of number passed."""
number = compact(number)
if len(number) == 10:
if not number[:-1].isdigit():
return None
if _calc_isbn10_check_digit(number[:-1]) != number[-1]:
return None
return 'ISBN10'
elif len(number) == 13:
if not number.isdigit():
return None
if _calc_isbn13_check_digit(number[:-1]) != number[-1]:
return None
return 'ISBN13'
else:
return None
def validate(number):
"""Checks to see if the number provided is a valid ISBN (either a legacy
10-digit one or a 13-digit one). This checks the length and the check
bit but does not check if the group and publisher are valid (use split()
for that)."""
return isbn_type(number) is not None
def to_isbn13(number):
"""Convert the number to ISBN13 format."""
number = number.strip()
min_number = compact(number)
if len(min_number) == 13:
return number # nothing to do, already ISBN13
# put new check digit in place
number = number[:-1] + _calc_isbn13_check_digit('978' + min_number[:-1])
# add prefix
if ' ' in number:
return '978 ' + number
elif '-' in number:
return '978-' + number
else:
return '978' + number
def split(number):
"""Split the specified ISBN into an EAN.UCC prefix, a group prefix, a
registrant, an item number and a check-digit. If the number is in ISBN10
format the returned EAN.UCC prefix is '978'."""
import ranges
# clean up number
number = compact(number)
# get Bookland prefix if any
if len(number) == 10:
oprefix = ''
prefix = '978'
else:
oprefix = prefix = number[:3]
number = number[3:]
# get group
group, number = ranges.lookup(prefix, number)
publisher, number = ranges.lookup('%s-%s' % (prefix, group), number)
itemnr = number[:-1]
check = number[-1]
return ( oprefix, group, publisher, itemnr, check )
def format(number, separator='-'):
"""Reformat the passed number to the standard format with the EAN.UCC
prefix (if any), the group prefix, the registrant, the item number and
the check-digit separated (if possible) by the specified separator.
Passing an empty separator should equal compact() though this is less
efficient."""
return separator.join(x for x in split(number) if x)
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