81 lines
2.4 KiB
Python
81 lines
2.4 KiB
Python
import string
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ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
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def from_base(number, base, alphabet=None):
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if base < 2:
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raise ValueError('base must be >= 2.')
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if not isinstance(base, int):
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raise TypeError('base must be an int.')
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if base == 10:
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return int(number)
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if alphabet is None:
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alphabet = ALPHABET
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number = str(number)
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alphabet = alphabet[:base]
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if number.count('.') > 1:
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raise ValueError('Too many decimal points')
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mixed_case = any(c in string.ascii_uppercase for c in alphabet) and \
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any(c in string.ascii_lowercase for c in alphabet)
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if not mixed_case:
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alphabet = alphabet.upper()
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number = number.upper()
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char_set = set(number.replace('.', '', 1))
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alpha_set = set(alphabet)
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differences = char_set.difference(alpha_set)
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if len(differences) > 0:
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raise ValueError('Unknown characters for base', base, differences)
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alpha_dict = {character:index for (index, character) in enumerate(alphabet)}
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try:
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decimal_pos = number.index('.')
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except ValueError:
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decimal_pos = len(number)
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result = 0
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for (index, character) in enumerate(number):
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if index == decimal_pos:
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continue
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power = (decimal_pos - index)
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if index < decimal_pos:
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power -= 1
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value = alpha_dict[character] * (base ** power)
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#print(value)
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result += value
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return result
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def to_base(number, base, decimal_places=10, alphabet=None):
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if base < 2:
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raise ValueError('base must be >= 2.')
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if not isinstance(base, int):
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raise TypeError('base must be an int.')
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if base == 10:
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return str(number)
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if alphabet is None:
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alphabet = ALPHABET
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if base > len(alphabet):
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raise ValueError('Not enough symbols in alphabet for base %d' % base)
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result = ''
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whole_portion = int(number)
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float_portion = number - whole_portion
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while whole_portion > 0:
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(whole_portion, remainder) = divmod(whole_portion, base)
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result = alphabet[remainder] + result
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if float_portion != 0:
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result += '.'
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for x in range(decimal_places):
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float_portion *= base
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whole = int(float_portion)
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float_portion -= whole
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result += alphabet[whole]
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return result
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