python正则表达式不一致

re.sub() 不能接受 re.IGNORECASE 看来是这样。

文件规定:

sub(pattern, repl, string, count=0)

Return the string obtained by replacing the leftmost
non-overlapping occurrences of the pattern in string by the
replacement repl.  repl can be either a string or a callable;
if a string, backslash escapes in it are processed.  If it is
a callable, it's passed the match object and must return
a replacement string to be used.

然而,在其位置上使用它是可行的:

re.sub("(?i)mr", "", "Mr Bean")

模块级sub()调用在末尾不接受修饰符。这是“count”参数-要替换的模式出现的最大数目。

>>> help(re.sub)
  1 Help on function sub in module re:
  2 
  3 sub(pattern, repl, string, count=0)
  4     Return the string obtained by replacing the leftmost
  5     non-overlapping occurrences of the pattern in string by the
  6     replacement repl.  repl can be either a string or a callable;
  7     if a callable, it's passed the match object and must return
  8     a replacement string to be used.

中没有函数参数 re.sub 对于regex标志( IGNORECASE, MULTILINE, DOTALL ) re.compile .

选择:

>>> re.sub("[M|m]r", "", "Mr Bean")
' Bean'

>>> re.sub("(?i)mr", "", "Mr Bean")
' Bean'

编辑 python 3.1增加了对regex标志的支持, http://docs.python.org/3.1/whatsnew/3.1.html . 自3.1起,如 re.sub 看起来像:

re.sub(pattern, repl, string[, count, flags])

从python 2.6.4文档中:

re.sub(pattern, repl, string[, count])

re.sub()不使用标志来设置regex模式。如果需要re.ignorecase,则必须使用re.compile().sub()。