如何在 Python 中每个正则表达式匹配组之前和之后添加字符串？

Question

I have a string and a regex with several groups. I want to add some string before and after each matched group. How can I do it? Below is the demo code only used to help describe my question.

data = "aa11bb123cc3333dd12eeeff3"
regex = re.compile(r"([a-z])\1(\d)(\d)(?=[a-z])")

The expected result is (using < and > to surround the matched groups):

<a>a<1><1>bb123cc3333<d>d<1><2>eeeff3

Please also consider regex group like (\\d)* and I don't know how many groups beforehand.

Answer 1

You can use your current regex ([az])\\1(\\d)(\\d)(?=[az]) and replace it with this,

<\1>\1<\2><\3>

Regex Demo

You can modify your code to use re.sub and get your expected output.

import re

data = "aa11bb123cc3333dd12eeeff3"
regex = re.compile(r"([a-z])\1(\d)(\d)(?=[a-z])")
print(re.sub(regex, r'<\1>\1<\2><\3>', data))

Prints like you expected,

<a>a<1><1>bb123cc3333<d>d<1><2>eeeff3

Also, as you updated your post, just clarifying that this regex (\\d)* only has one group only and it is not that there is * outside the group and it will make number of groups multiple. (\\d)* will behave same like \\d* except the captured digit in the group will be just one and exactly the last one that matched.