有人可以解释这个Python re.sub（）意外输出吗？

I am using Python 2.6 and am getting [what I think is] unexpected output from re.sub()

我正在使用Python 2.6并从re.sub()获得[我认为]的意外输出

>>> re.sub('[aeiou]', '-', 'the cat sat on the mat')
'th- c-t s-t -n th- m-t'
>>> re.sub('[aeiou]', '-', 'the cat sat on the mat', re.IGNORECASE)
'th- c-t sat on the mat'

If this output is what is expected, what is the logic behind it?

如果这个输出是预期的,它背后的逻辑是什么?

3 个解决方案

#1

Yes, the fourth parameter is count, not flags. You're telling it to apply the pattern twice (re.IGNORECASE = 2).

是的,第四个参数是count,而不是flags。你告诉它应用模式两次(re.IGNORECASE = 2)。

#2

To pass flags you can use re.compile

要传递标记,可以使用re.compile

expression = re.compile('[aeiou]', re.IGNORECASE)
expression.sub('-', 'the cat sat on the mat')

#3

In case you've upgraded since asking this question. If you are using Python 2.7+, you don't need to use re.compile. You can call sub and specify flags with a named argument.

如果你问这个问题后你已经升级了。如果您使用的是Python 2.7+,则无需使用re.compile。您可以调用sub并使用命名参数指定标志。

>>> import re
>>> re.sub('[aeiou]', '-', 'the cat sat on the mat', flags=re.IGNORECASE)
'th- c-t s-t -n th- m-t'

Reference: https://docs.python.org/2/library/re.html#re.sub

#1