Python 2.7 Regex捕获组无法按预期工作

Question

I am trying to pattern match and replace first person with second person with Python 2.7.

string = re.sub(r'(\W)I(\W)', '\g<1>you\g<2>',string)
string = re.sub(r'(\W)(me)(\W)', '\g<1>you\g<3>',string)
# but does NOT work
string = re.sub(r'(\W)I|(me)(\W)', '\g<1>you\g<3>',string)

I want to use the last regex, but somehow the capture groups are all messed up and even doing a \\g<0> shows strange, irregular matches. I would think that capture group 3 would be the last word boundary, but it doesn't appear to be.

A sample sentence could be: I like candy.

I am not interested very much in the correctness of the replacement (me will never actually be selected since I goes first), but I don't know why the capture groups don't work as I would expect.

Thanks!

Answer 1

Try with following regex.

Regex: \\b(I|me)\\b

Explanation:

• \\b on both sides marks the word boundary.

• (I|me) matches either I OR me .

Note:- You can make it case insensitive using i flag.

Regex101 Demo