python匹配多行

Question

I am trying to extract a portion of a multi-line string. Specifically, I'd like to pull out the list of terms between the center pair of braces:

'my datagroup 2.5 {\n    nose-capabilities {\n        none\n        slow\n        800\n        1200\n    }\n}\n'

I've tried this:

re.findall('.*{.*{(?:\s*(\S+)\s*)*}\s*}', d, re.S)

# ['1200']

So I'm only getting the last capture as far as I can tell. ?

Answer 1

If you are trying to do this using regex, you would be better off using re.search and a lookahead assertion.

>>> re.search(r'(?s){(?!.*{)([^}]*)', d).group(1).split()
['none', 'slow', '800', '1200']

Answer 2

I think you're missing the point of findall . It returns one value for every match of the entire pattern. If you want multiple groups in one pattern, that's fine, but you don't need findall for that.

In fact, you really don't need that. You can just replace the whole middle of your pattern with (.*?) to trivially capture everything between the second open brace and the first close brace.

Note the non-greedy match; otherwise, it would suck up everything up to the last close brace, instead of up to the first . (You could use a lookahead assertion for this, but non-greedy matches are simpler.)

>>> re.findall('.*{.*{(.*?)}', d, re.S)
['\n        none\n        slow\n        800\n        1200\n    ']

Although of course findall still isn't doing you any good:

>>> re.search('.*{.*{(.*?)}', d, re.S).group(1)
'\n        none\n        slow\n        800\n        1200\n    '

Anyway, once you have that, you can just split it:

>>> re.search('.*{.*{(.*?)}', d, re.S).group(1).split()
['none', 'slow', '800', '1200']

Answer 3

Answer for any number of nested braces:

s = 'my datagroup 2.5 {\n    nose-capabilities {\n        none\n        slow\n        800\n        1200\n    }\n}\n'
# the position of the inner brace
start = s.rfind('{') + 1
end = s.find('}')
# find alphanumeric characters in substring
re.findall('\w+', s[start:end])