regex - Lookarounds in python -

i have problem regarding lookarounds in python:

>>> spacereplace = re.compile(b'(?<!\band)(?<!\bor)\s(?!or\b)(?!and\b)', re.i) >>> q = "a b (c or d)"     >>> q = spacereplace.sub(" , ", q) >>> q # meant happen: 'a , b , (c or d)'  # instead happens 'a , b , (c , or , d)' 

the regex supposed match space not next words "and" or "or", doesn't seem working.

can me this?

edit: in response commentor, broken down regex multiple lines.

(?<!\band) # looks behind \s, matching if there isn't word break, followed "and", there. (?<!\bor)  # looks behind \s, matching if there isn't word break, followed "or", there. \s         # matches single whitespace character. (?!or\b)   # looks after \s, matching if there isn't word "or", followed word break there. (?!and\b)  # looks after \s, matching if there isn't word "and", followed word break there. 

you presumably confused raw string modifier r b.

>>> import re >>> spacereplace = re.compile(r'(?<!\band)(?<!\bor)\s(?!or\b)(?!and\b)', re.i) >>> q = "a b (c or d)" >>> spacereplace.sub(" , ", q) 'a , b , (c or d)'  

sometimes, if regexp doesn't work, may debug re.debug flag. in case doing may notice, word boundary \b not detected, may give hint search mistake:

>>> spacereplace = re.compile(b'(?<!\band)(?<!\bor)\s(?!or\b)(?!and\b)', re.i | re.debug) assert_not -1   literal 8   literal 97   literal 110   literal 100 assert_not -1   literal 8   literal 111   literal 114 in   category category_space assert_not 1   literal 111   literal 114   literal 8 assert_not 1   literal 97   literal 110   literal 100   literal 8   >>> spacereplace = re.compile(r'(?<!\band)(?<!\bor)\s(?!or\b)(?!and\b)', re.i | re.debug) assert_not -1   @ at_boundary   literal 97   literal 110   literal 100 assert_not -1   @ at_boundary   literal 111   literal 114 in   category category_space assert_not 1   literal 111   literal 114   @ at_boundary assert_not 1   literal 97   literal 110   literal 100   @ at_boundary