Match path but not os.path

Question

I want to match the string path but not the string os.path. How do I go about that ? Tried (?!(os\.path))\bpath\b but I still get all os.pathS

@SebastianProske: seems to work - could you add an answer explaining why it works and how I can be sure it will mathc complex cases like `if path and not os.path.sep in path` for instance — Mr_and_Mrs_D, Oct 15 '16 at 13:32
From the given string, do you want to match all occurences of path that are not connected to os. or none at all? — Sebastian Proske, Oct 15 '16 at 13:33
I want all lines that contain the word path but not os.path only (or sys.path for that matter) so the line above should be a match — Mr_and_Mrs_D, Oct 15 '16 at 13:35

score 1 · Accepted Answer · answered Oct 15 '16 at 13:41

1

You can use a look-behind based regex, like

(?<!os\.)\bpath\b

This basically matches the exact word path and ensures that it is not preceded by os. If you want to avoid similar constructs, like sys.path or xx.path you could use (?<!\w\.) as look-behind instead.

See the regex101 demo.

answered Oct 15 '16 at 13:41

Sebastian Proske

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Thanks! why was mine failing so miserably ? – Mr_and_Mrs_D Oct 15 '16 at 13:43
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Your lookebhind was starting at the same position, as your match started, thus directly in front of `path` - and thus would always be correct. You might check this with `(?!(os\.path))..\.\bpath\b`... – Sebastian Proske Oct 15 '16 at 13:45

score 0 · Answer 2 · answered Oct 15 '16 at 13:49

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If you want to skip any path starting with . try

(?<!\.)path

This will skip sys.path or os.path but will match path.

e.g. if test strings is if path and not os.path.sep in path,

match will be:

if path and not os.path.sep in path

See demo at regex101

answered Oct 15 '16 at 13:49

Saleem

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Match path but not os.path

2 Answers2