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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):
decode_mapping = {}
def __init__(self, digits):
self.digits = digits
self.length = len(digits)
def from_decimal(self, i):
if i < 0:
i, neg = -i, 1
else:
neg = 0
enc = ''
while i >= self.length:
i, mod = divmod(i, self.length)
enc = self.digits[mod] + enc
enc = self.digits[i] + enc
if neg:
enc = '-' + enc
return enc
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
if str(s)[0] == '-':
s, neg = str(s)[1:], 1
else:
neg = 0
decoded = 0
multi = 1
while len(s) > 0:
decoded += multi * self.digits.index(s[-1:])
multi = multi * self.length
s = s[:-1]
if neg:
decoded = -decoded
return decoded
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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