Deleting specific characters from a string

Paul Rudin paul_rudin at scientia.com
Thu Jul 10 13:06:08 CEST 2003


>>>>> "Jeff" == Jeff Hinrichs <jlh at cox.net> writes:


    > I've been following this thread, and on a whim I built a test
    > harness to time the different ideas that have been put forth in
    > this thread.  I will post complete results tomorrow on the web
    > but the short version is that using the .replace method is the
    > overall champ by quite a bit.  Below is the function I tested
    > against the others in the harness:

    > def stringReplace(s,c): """Remove any occurrences of characters
    > in c, from string s s - string to be filtered, c - characters to
    > filter""" for a in c: s = s.replace(a,'') return s

    > It wins also by being easy to understand, no filter or lambda.
    > Not that I have anything against filter or lambda, but when the
    > speediest method is the most readable, that solution is
    > definitely the Pythonic champ. :)

I haven't been following this thread closely but isn't a regexp the
obvious way to do this? I'd expect it to be faster than your solution
- particularly on large input (although I haven't actually
tried). Arguably it's more pythonic too :-)

re.compile(r).sub('',s)

where r is the obvious disjunctive regexp mentioning each of the
charaters you want to remove. If you want to construct such a regexp
from a list of characters:

r= reduce(lambda x,y: x+'|'+y, c,'')[1:]

So putting it all together as an alternative version of your fuction:


!!warning - untested code!!

import re

def stringReplace(s,c):
    r= reduce(lambda x,y: x+'|'+y, c,'')[1:]
    return re.compile(r).sub('',s)




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