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"""
Convert numbers from base 10 integers to base X strings and back again.
Original: http://www.djangosnippets.org/snippets/1431/
Sample usage:
>>> base20 = BaseConverter('0123456789abcdefghij')
>>> base20.from_decimal(1234)
'31e'
>>> base20.to_decimal('31e')
1234
"""
class BaseConverter(object):
decimal_digits = "0123456789"
decode_mapping = {}
def __init__(self, digits):
self.digits = digits
def from_decimal(self, i):
return self.convert(i, self.decimal_digits, self.digits)
def to_decimal(self, s):
if self.decode_mapping:
new = ''
for digit in s:
if digit in self.decode_mapping:
new += self.decode_mapping[digit]
else:
new += digit
s = new
return int(self.convert(s, self.digits, self.decimal_digits))
def convert(number, fromdigits, todigits):
# Based on http://code.activestate.com/recipes/111286/
if str(number)[0] == '-':
number = str(number)[1:]
neg = 1
else:
neg = 0
# make an integer out of the number
x = 0
for digit in str(number):
x = x * len(fromdigits) + fromdigits.index(digit)
# create the result in base 'len(todigits)'
if x == 0:
res = todigits[0]
else:
res = ""
while x > 0:
digit = x % len(todigits)
res = todigits[digit] + res
x = int(x / len(todigits))
if neg:
res = '-' + res
return res
convert = staticmethod(convert)
bin = BaseConverter('01')
hexconv = BaseConverter('0123456789ABCDEF')
base62 = BaseConverter(
'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz'
)
class Base32Converter(BaseConverter):
"""
http://www.crockford.com/wrmg/base32.html
"""
decode_mapping = {
'o': '0',
'i': '1',
'l': '1',
}
def __init__(self):
super(Base32Converter, self).__init__('0123456789abcdefghjkmnpqrstvwxyz')
def to_decimal(self, s):
return super(Base32Converter, self).to_decimal(s.lower())
base32 = Base32Converter()
if __name__ == '__main__':
import doctest
doctest.testmod()
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