I'd like to match strings like:
45 meters?
45, meters?
45?
45 ?
but not strings like:
45 meters you?
45 you ?
45, and you?
In both cases the question mark must be at the end. So, essentially I want to exclude all those strings containing the word "you".
I've tried the following regex:
'\d+.*(?!you)\?$'
but it matches the second case (probably because of .*)
You could try this regex to match all the lines which doesn't have the string you with ? at the last,
^(?!.*you).*\?$
Explanation:
A negative lookahead is used in this regex. What it does actually means, it checks for the lines which contains a string you. It matches all the lines except the line containing the string you.
you.
., because it should even match 45, meters?
^[\d,]+ ?(\w+)?\?$?42 test meters?^(?!.*you).*\?$' because as I wrote, I also need the question mark at the end of the string. Thank you!!!There's a neat trick to exclude some matches from a regex, which you can use here:
>>> import re
>>> corpus = """
... 45 meters?
... 45?
... 45 ?
... 45 meters you?
... 45 you ?
... 45, and you?
... """
>>> pattern = re.compile(r"\d+[^?]*you|(\d+[^?]*\?)")
>>> re.findall(pattern, corpus)
['45 meters?', '45?', '45 ?', '', '', '']
The downside is that you get empty matches when the exclusion kicks in, but those are easily filtered out:
>>> filter(None, re.findall(pattern, corpus))
['45 meters?', '45?', '45 ?']
How it works:
The trick is that we only pay attention to captured groups ... so the left hand side of the alternation - \d+[^?]*you (or "digits followed by non-?-characters followed by 'you'") matches what you don't want, and then we forget about it. Only if the left hand side doesn't match is the right hand side - (\d+[^?]*\?) (or "digits followed by non-?-characters followed by '?') - matched, and that one is captured.
youoccur anywhere in the string, or only at the end?youand?there could be some white spaces.\d+.*?(?<!you\?)$, but it will also match45 you ?. You can't do(?<!you\s*\?)because lookbehinds (in most flavors) need to be fixed-length."you" in mystring