Re: count string replace occurances
Xah Lee <[EMAIL PROTECTED]> wrote: > if i have > mytext.replace(a,b) > how to find out many many occurances has been replaced? If 'a' and 'b' are different length, - Count the string length, before and after. The difference should be multiple of difference between length of 'a' and 'b'. If they are same length, - Split 'mytext', and count items. -- William Park <[EMAIL PROTECTED]>, Toronto, Canada ThinFlash: Linux thin-client on USB key (flash) drive http://home.eol.ca/~parkw/thinflash.html -- http://mail.python.org/mailman/listinfo/python-list
Re: count string replace occurances
"Jeff Epler" wrote:
> On Sun, Jun 12, 2005 at 04:55:38PM -0700, Xah Lee wrote:
> > if i have
> > mytext.replace(a,b)
> > how to find out many many occurances has been replaced?
>
> The count isn't returned by the replace method. You'll have to count
> and then replace.
>
> def count_replace(a, b, c):
> count = a.count(b)
> return count, s.replace(b, c)
>
> >>> count_replace("a car and a carriage", "car", "bat")
> (2, 'a bat and a batriage')
I thought naively that scanning a long string twice would be almost
twice as slow compared to when counting was done along with replacing.
Although it can done with a single scan, it is almost 9-10 times
slower, mainly because of the function call overhead; the code is also
longer:
import re
def count_replace_slow(aString, old, new):
count = [0]
def counter(match):
count[0] += 1
return new
replaced = re.sub(old,counter,aString)
return count[0], replaced
A good example of trying to be smart and failing :)
George
--
http://mail.python.org/mailman/listinfo/python-list
Re: count string replace occurances
On Sun, Jun 12, 2005 at 04:55:38PM -0700, Xah Lee wrote:
> if i have
> mytext.replace(a,b)
> how to find out many many occurances has been replaced?
The count isn't returned by the replace method. You'll have to count
and then replace.
def count_replace(a, b, c):
count = a.count(b)
return count, s.replace(b, c)
>>> count_replace("a car and a carriage", "car", "bat")
(2, 'a bat and a batriage')
pgpAvDTGPd6LT.pgp
Description: PGP signature
--
http://mail.python.org/mailman/listinfo/python-list
