String search vs regexp search

[Anand Pillai]

To search a word in a group of words, say a paragraph or a web page,
would a string search or a regexp search be faster?

The string search would of course be,

if str.find(substr ) != -1:
domything()

And the regexp search assuming no case restriction would be,

strre=re.compil e(substr, re.IGNORECASE)

m=strre.search( str)
if m:
domything()

I was about to do a test, then I thought someone here might have
some data on this already.

Thanks folks!

-Anan

[Anand Pillai]

Small point. If you notice the code, compilation time is
not included in the actual time calculated for regexp.

-Anand

tw*********@hot mail.com (Jeremy Fincher) wrote in message news:<69******* *************** ****@posting.go ogle.com>...

Duncan Booth <du****@NOSPAMr cp.co.uk> wrote in message news:<Xn******* *************** *****@127.0.0.1 >...

The regular expression code has a startup penalty since it has to compile
the regular expression at least once, however the actual searching may be
faster than the naive str.find. If the time spent doing the search is
sufficiently long compared with the time doing the compile, the regular
expression may win out.

Both regular expression searching and string.find will do searching
one character at a time; given that, it seems impossible to me that
the hand-coded-in-C "naive" string.find could be slower than the
machine-translated-coded-in-Python regular expression search.
Compilation time only serves to further increase string.find's
advantage.

Jeremy