如何使用每个字母的2个字母表字符将字符串转换为自定义基

Question

下面的函数将数字255 (base10)转换为'FF' (base16)，使用base16字母表'0123456789ABCDEF'。

我很难理解如何修改这些函数，以便它们使用每个字母中的2个字符，这样数字255 (base10)就可以使用修改后的base16字母表'x0x1x2x3x4x5x6x7x8x9xAxBxCxDxExF'转换成'xFxF' (base16)。

def v2r(num, alphabet):
  """Convert base 10 number into a string of a custom base (alphabet)."""
  alphabet_length = len(alphabet)
  result = ''
  while num > 0:
    result = alphabet[num % alphabet_length] + result
    num  = num // alphabet_length
  return result


def r2v(data, alphabet):
  """Convert string of a custom base (alphabet) back into base 10 number."""
  alphabet_length = len(alphabet)
  num = 0
  for char in data:
    num = alphabet_length * num + alphabet[:alphabet_length].index(char)
  return num

base16 = v2r(255, '0123456789ABCDEF')
base10 = r2v(base16, '0123456789ABCDEF')
print(base16, base10)
# output: FF 255

# base16 = v2r(255, 'x0x1x2x3x4x5x6x7x8x9xAxBxCxDxExF')
# base10 = r2v(base16, 'x0x1x2x3x4x5x6x7x8x9xAxBxCxDxExF')
# print(base16, base10)
# output: xFxF 255

Answer 1

这里有一个可能的解决办法。我认为您的bug来自于python类型和可迭代性定义的混淆。

我修改了基本的16字母表，它现在是一个项目列表。然后，我也修改了一些函数，以考虑到这一点，而且它看起来很有效。

def v2r(num, alphabet):
    """Convert base 10 number into a string of a custom base (alphabet)."""
    alphabet_length = len(alphabet)
    result = []
    while num > 0:
        result = [alphabet[num % alphabet_length]] + result
        num  = num // alphabet_length
    return result


def r2v(data, alphabet):
    """Convert string of a custom base (alphabet) back into base 10 number."""
    alphabet_length = len(alphabet)
    num = 0
    for char in data:
        num = alphabet_length * num + alphabet.index(char)
    return num

alphabet = [
    'x0','x1', 'x2', 'x3', 'x4', 'x5', 'x6', 'x7', 'x8',
    'x9', 'xA', 'xB', 'xC', 'xD', 'xE', 'xF'
]
base16 = v2r(255, alphabet)
base10 = r2v(base16, alphabet)
print(''.join(base16), base10)
#  xFxF 255

下面是OP的注释:只需声明以下字母表：

hexa = '0123456789abcdef'
alphabet = [
    a+b for a in hexa for b in hexa
]

Answer 2

我建议在开始计算之前删除“x”，因此添加作为函数的第一行

alphabet=alphabet.replace('x','')

因此，您的函数将与两个系统“FFF”或“xFxFxF”一起工作。

def v2r(num, alphabet):
  """Convert base 10 number into a string of a custom base (alphabet)."""
  alphabet=alphabet.replace('x','') ### added
  alphabet_length = len(alphabet)
  result = ''
  while num > 0:
    result = alphabet[num % alphabet_length] + result
    num  = num // alphabet_length
  return result


def r2v(data, alphabet):
  """Convert string of a custom base (alphabet) back into base 10 number."""
  alphabet=alphabet.replace('x','') ### added
  alphabet_length = len(alphabet)
  num = 0
  for char in data:
    num = alphabet_length * num + alphabet[:alphabet_length].index(char)
  return num