kopia lustrzana https://github.com/simonw/datasette
60 wiersze
1.5 KiB
Python
60 wiersze
1.5 KiB
Python
"""
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Convert numbers from base 10 integers to base X strings and back again.
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Sample usage:
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>>> base20 = BaseConverter('0123456789abcdefghij')
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>>> base20.from_decimal(1234)
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'31e'
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>>> base20.to_decimal('31e')
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1234
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Originally shared here: https://www.djangosnippets.org/snippets/1431/
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"""
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class BaseConverter(object):
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decimal_digits = "0123456789"
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def __init__(self, digits):
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self.digits = digits
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def encode(self, i):
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return self.convert(i, self.decimal_digits, self.digits)
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def decode(self, s):
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return int(self.convert(s, self.digits, self.decimal_digits))
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def convert(number, fromdigits, todigits):
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# Based on http://code.activestate.com/recipes/111286/
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if str(number)[0] == "-":
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number = str(number)[1:]
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neg = 1
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else:
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neg = 0
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# make an integer out of the number
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x = 0
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for digit in str(number):
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x = x * len(fromdigits) + fromdigits.index(digit)
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# create the result in base 'len(todigits)'
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if x == 0:
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res = todigits[0]
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else:
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res = ""
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while x > 0:
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digit = x % len(todigits)
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res = todigits[digit] + res
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x = int(x / len(todigits))
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if neg:
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res = "-" + res
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return res
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convert = staticmethod(convert)
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bin = BaseConverter("01")
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hexconv = BaseConverter("0123456789ABCDEF")
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base62 = BaseConverter("ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz")
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