unbalanced parenthesis error using re.search python

Question

I have a list that I want to loop through (for trimtemp in trim) and see if it has any matches in a given string (modeltrim). The code runs fine most of the time however, every now and then it gives me the following error:

Traceback (most recent call last):
  File "/home/hostadl/PricesFinal.py", line 318, in <module>
    main()
  File "/home/hostadl/PricesFinal.py", line 215, in main
    match = re.search(r'{0}'.format(trimtemp), modeltrim, re.IGNORECASE)
  File "/usr/local/lib/python3.2/re.py", line 158, in search
    return _compile(pattern, flags).search(string)
  File "/usr/local/lib/python3.2/re.py", line 256, in _compile
    return _compile_typed(type(pattern), pattern, flags)
  File "/usr/local/lib/python3.2/functools.py", line 180, in wrapper
    result = user_function(*args, **kwds)
  File "/usr/local/lib/python3.2/re.py", line 268, in _compile_typed
    return sre_compile.compile(pattern, flags)
  File "/usr/local/lib/python3.2/sre_compile.py", line 491, in compile
    p = sre_parse.parse(p, flags)
  File "/usr/local/lib/python3.2/sre_parse.py", line 692, in parse
    p = _parse_sub(source, pattern, 0)
  File "/usr/local/lib/python3.2/sre_parse.py", line 315, in _parse_sub
    itemsappend(_parse(source, state))
  File "/usr/local/lib/python3.2/sre_parse.py", line 642, in _parse
    raise error("unbalanced parenthesis")
sre_constants.error: unbalanced parenthesis

Your help would be greatly appreciated!

Please also post the code which errors out. We can pick out one relevant line from the trace, but need to see more of it. — Michael Berkowski, Jun 28 '12 at 02:27
Without knowing what is in `trimtemp`, we can't tell you any more than the error already does. The error would appear to be self explanatory though. — Hamish, Jun 28 '12 at 02:30

score 2 · Accepted Answer · answered Jun 28 '12 at 02:33

This line appears to be the problem

match = re.search(r'{0}'.format(trimtemp), modeltrim, re.IGNORECASE)

You should look at what format(trimtemp) contains. Perhaps add just add a

print format(trimtemp)

on the line before. Probably it is containing ( or ) which are of significance to re. Perhaps re.escape(format(trimtemp)) is what you need

unbalanced parenthesis error using re.search python

1 Answers1