string.maketrans(from, to)

  string.translate(s, table[, deletechars])
  str.translate(table[, deletechars])
  unicode.translate(table)

  static str.maketrans(x[, y[, z]])
  static bytes.maketrans(from, to)
  static bytearray.maketrans(from, to)

  str.translate(map)
  bytes.translate(table[, delete])
  bytearray.translate(table[, delete])

  >>> import string                     #导入string模块
  >>> map = string.maketrans('123', 'abc') #建立映射表，将字符串中含有的'1','2','3'替换为'a','b','c'
  >>> s = '54321123789'                #转换前的字符串
  >>> s.translate(map)                  #用创建的映射表map转换字符串
  '54cbaabc789'                        #转换后的字符串

  >>> map = str.maketrans('123','abc')
  >>> s = '54321123789'
  >>> s.translate(map)
  '54cbaabc789'

  >>> import string
  >>> map = string.maketrans('123', 'abc')
  >>> s = '54321123789'
  >>> s.translate(map, '78')        #除了转换，还要删除字符串中的字符'7','8'
  '54cbaabc9'               #转换后的字符串没有字符'7','8'

  >>> map = str.maketrans('123','abc', '78')#要删除的字符需要在这指定
  >>> s = '54321123789'
  >>> s.translate(map)
  '54cbaabc9'

  import string
  def translator(frm='', to='', delete='', keep=None):
    if len(to) == 1:
      to = to * len(frm)
    trans = string.maketrans(frm, to)
    if keep is not None:
      allchars = string.maketrans('', '')
      delete = allchars.translate(allchars, keep.translate(allchars,delete))
    def translate(s):
      return s.translate(trans, delete)
    return translate

  >>> import string
  >>> map = string.maketrans('123', 'abc')
  >>> type(map)
  <type 'str'>

  >>> map = str.maketrans('123','abc')
  >>> type(map)
  <class 'dict'>

  >>> print u"hallo".translate({97:u'e'})
  hello
  >>> print u"hallo".translate({'a':u'e'})
  hallo
  >>> print u"hallo".translate({u'a':u'e'})
  hallo