On Sat, 05 Sep 2009 22:54:41 +0100, per <perfr...@gmail.com> wrote:
I'm trying to efficiently "split" strings based on what substrings
they are made up of.
i have a set of strings that are comprised of known substrings.
For example, a, b, and c are substrings that are not identical to each
other, e.g.:
a = "0" * 5
b = "1" * 5
c = "2" * 5
Then my_string might be:
my_string = a + b + c
i am looking for an efficient way to solve the following problem.
suppose i have a short
string x that is a substring of my_string. I want to "split" the
string x into blocks based on
what substrings (i.e. a, b, or c) chunks of s fall into.
to illustrate this, suppose x = "00111". Then I can detect where x
starts in my_string
using my_string.find(x). But I don't know how to partition x into
blocks depending
on the substrings. What I want to get out in this case is: "00",
"111". If x were "001111122",
I'd want to get out "00","11111", "22".
is there an easy way to do this? i can't simply split x on a, b, or c
because these might
not be contained in x. I want to avoid doing something inefficient
like looking at all substrings
of my_string etc.
i wouldn't mind using regular expressions for this but i cannot think
of an easy regular
expression for this problem. I looked at the string module in the
library but did not see
anything that seemd related but i might have missed it.
I'm not sure I understand your question exactly. You seem to imply
that the order of the substrings of x is consistent. If that's the
case, this ought to help:
import re
x = "001111122"
m = re.match(r"(0*)(1*)(2*)", x)
m.groups()
('00', '11111', '22')
y = "00111"
m = re.match(r"(0*)(1*)(2*)", y)
m.groups()
('00', '111', '')
You'll have to filter out the empty groups for yourself, but that's
no great problem.
--
Rhodri James *-* Wildebeest Herder to the Masses
--
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