python过滤字符串中不属于指定集合中字符的类实例

本文实例讲述了python过滤字符串中不属于指定集合中字符的类。分享给大家供大家参考。具体如下：

# -*- coding: utf-8 -*-
import sets
class Keeper(object):
  def __init__(self, keep):
    self.keep = sets.Set(map(ord, keep))
  def __getitem__(self, n):
    if n not in self.keep:
      return None
    return unichr(n)
  def __call__(self, s):
    return s.translate(self)
makefilter = Keeper
if __name__ == \'__main__\':
  just_vowels = makefilter(\'aeiouy\')
  print just_vowels(u\'four score and seven years ago\')
  # 输出: ouoeaeeyeaao
  print just_vowels(u\'tiger, tiger burning bright\')
  # 输出: ieieuii

希望本文所述对大家的Python程序设计有所帮助。