import re
a = 'abc123dd234fhgg'
p1 = re.compile(r'\d+(?=\D+)')
a1 = p1.sub(r'45', a,1)
a2 = p1.sub(r'456',a,1)

print(f'a1 should be: {a1}, and a2: {a2}')

这个也可以

嗯，可以，谢谢

(?=\D+)或者(?<=\D\D\D)，您这个写法能解释一下吗？有点困惑，谢谢

房事不决问百度！

(?<=...)
Matches if the current position in the string is preceded by a match for ... that ends at the current position. This is called a positive lookbehind assertion. (?<=abc)def will find a match in 'abcdef', since the lookbehind will back up 3 characters and check if the contained pattern matches. The contained pattern must only match strings of some fixed length, meaning that abc or a|b are allowed, but a* and a{3,4} are not. Note that patterns which start with positive lookbehind assertions will not match at the beginning of the string being searched; you will most likely want to use the search() function rather than the match() function:

>>>
>>> import re
>>> m = re.search('(?<=abc)def', 'abcdef')
>>> m.group(0)
'def'
This example looks for a word following a hyphen:

>>>
>>> m = re.search(r'(?<=-)\w+', 'spam-egg')
>>> m.group(0)
'egg'


(?=...)
Matches if ... matches next, but doesn’t consume any of the string. This is called a lookahead assertion. For example, Isaac (?=Asimov) will match 'Isaac ' only if it’s followed by 'Asimov'.