python清除字符串中非字母字符(python正则表达式)

#!/bin/python/env
#site: www.jb200.com
#
 
s = "hello world! how are you? 0" 

# Short version 
print filter(lambda c: c.isalpha(), s) 

# Faster version for long ASCII strings: 
id_tab = "".join(map(chr, xrange(256))) 
tostrip = "".join(c for c in id_tab if c.isalpha()) 
print s.translate(id_tab, tostrip) 

# Using regular expressions 正则表达式
print re.sub("[^A-Za-z]", "", s)