正则表达式匹配字符串之间的单个字符

Question

I have a string with some markup which I'm trying to parse, generally formatted like this.

'[*]\r\n[list][*][*][/list][*]text[list][*][/list]'

I want to match the asterisks within the [list] tags so I can re.sub them as [**] but I'm having trouble forming an expression to grab them. So far, I have:

match = re.compile('\[list\].+?\[/list\]', re.DOTALL)

This gets everything within the list, but I can't figure out a way to narrow it down to the asterisks alone. Any advice would be massively appreciated.

Answer 1

You may use a re.sub and use a lambda in the replacement part. You pass the match to the lambda and use a mere .replace('*','**') on the match value.

Here is the sample code:

import re
s = '[*]\r\n[list][*][*][/list][*]text[list][*][/list]'
match = re.compile('\[list].+?\[/list]', re.DOTALL)
print(match.sub(lambda m: m.group().replace('*', '**'), s))
# = > [*]
#     [list][**][**][/list][*]text[list][**][/list]

See the IDEONE demo

Note that a ] outside of a character class does not have to be escaped in Python re regex.