Python正则表达式不一致

Question

根据我是否预编译正则表达式,我得到了不同的结果:

>>> re.compile('mr', re.IGNORECASE).sub('', 'Mr Bean')
' Bean'
>>> re.sub('mr', '', 'Mr Bean', re.IGNORECASE)
'Mr Bean'

在Python文档说,有些功能是用于编译正则表达式的功能齐全的方法简化版本.但是它也声称RegexObject.sub()与sub()函数相同.

那么这里发生了什么？

Answer 1

re.sub()re.IGNORECASE它似乎无法接受.

文件说明:

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,使用它可以取代它:

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

Answer 2

模块级sub()调用最后不接受修饰符.这就是"count"参数 - 要替换​​的模式最大出现次数.