What is built-in method sub

Diez B. Roggisch deets at nospam.web.de
Mon Jan 11 21:15:25 CET 2010

Jeremy schrieb:
> On Jan 11, 12:54 pm, Carl Banks <pavlovevide... at gmail.com> wrote:
>> On Jan 11, 11:20 am, Jeremy <jlcon... at gmail.com> wrote:
>>> I just profiled one of my Python scripts and discovered that >99% of
>>> the time was spent in
>>> {built-in method sub}
>>> What is this function and is there a way to optimize it?
>> I'm guessing this is re.sub (or, more likely, a method sub of an
>> internal object that is called by re.sub).
>> If all your script does is to make a bunch of regexp substitutions,
>> then spending 99% of the time in this function might be reasonable.
>> Optimize your regexps to improve performance.  (We can help you if you
>> care to share any.)
>> If my guess is wrong, you'll have to be more specific about what your
>> sctipt does, and maybe share the profile printout or something.
>> Carl Banks
> Your guess is correct.  I had forgotten that I was using that
> function.
> I am using the re.sub command to remove trailing whitespace from lines
> in a text file.  The commands I use are copied below.  If you have any
> suggestions on how they could be improved, I would love to know.
> Thanks,
> Jeremy
> lines = self._outfile.readlines()
> self._outfile.close()
> line = string.join(lines)
> if self.removeWS:
>     # Remove trailing white space on each line
>     trailingPattern = '(\S*)\ +?\n'
>     line = re.sub(trailingPattern, '\\1\n', line)

line = line.rstrip()?


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