On Tue, Oct 08, 2002 at 08:07:18AM -0600, Chris Staskewicz wrote:
> Is there an efficient method to find all "continuous" substrings of a
> string. For example, in the word "green", I'd like to parse out:
>
> g, r, e, e, n, gr, re, ee, en, gre, ree, and so on...
$ perl -MString::Substrings -e 'print join ", ", substrings "greenpeace"'
Since installing this module brings in most of CPAN's Test:: tree and
its myriad dependencies, here are the guts of it:
my $strlength = length($string);
my @s = ();
if (defined $length) {
return @s if $length == 0;
push @s, map {substr $string, $_, $length} (0 .. $strlength-$length);
} else {
foreach my $length (1 .. $strlength) {
push @s, map {substr $string, $_, $length}
(0 .. $strlength - $length);
}
}
return @s;
So this is O(n^2)...
The manpage also suggests looking at Algorithm::ChooseSubsets
HTH,
</lurk>,
Paul (who hasn't re-adjusted his filter since the list move :-)
--
Paul Makepeace ....................................... http://paulm.com/
"What is the square root of a duck? Death is the spoiler of all."
-- http://paulm.com/toys/surrealism/
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