python - 有没有办法撤消递归正则表达式操作？

Question

如果有一个正则表达式操作进行递归替换，例如:

>>> import re
>>> pattern = re.compile(r'[?!]')
>>> s = 'what the?!'
>>> print(pattern.sub(r' \g<0> ', s))
what the ?  !

有没有办法撤消递归操作？

我有这个，但它不起作用:

>>> import re
>>> pattern = re.compile(r'[?!]')
>>> s2 = pattern.sub(r' \g<0> ', s)
>>> s2
'what the ?  ! '
>>> pattern2 = re.compile(r'\s[?!]\s')
>>> s3 = pattern2.sub(r'\g<0>', s2)
>>> s3
'what the ?  ! '
>>> pattern2 = re.compile(r' [?!] ')
>>> s3 = pattern2.sub(r'\g<0>', s2)
>>> s3
'what the ?  ! '

<小时/>

Answer 1

您必须将字符类括在括号中才能创建 group 。然后在替换过程中，您可以将整个匹配项(包括空格)替换为组(不包含空格)。

>>> import re
>>> s2 = 'what the ?  ! '
>>> pattern2 = re.compile(r'\s([?!])\s')  # capture the punctuation part as group 1
>>> s3 = pattern2.sub(r'\g<1>', s2)       # replace the matches with the captured group 1
>>> s3
'what the?!'