You can use regex to extract the data, but I'd reach for something like Set::IntSpan to handle the intervals.

#!/usr/bin/perl
use warnings;
use strict;

use Set::IntSpan;

my $data = '43:1:1; 43:1:2; 43:1:3; 43:1:4; 43:1:5; 43:1:6; 27:3:7; 27
+:3:8; 27:3:9; 65:1:4; 65:1:18';

my %result;
my $out = sub {
    my $key = (keys %result)[0] or return;
    print "$key:", delete $result{$key}, ';';
};
while ($data =~ /([0-9]+:[0-9]+):([0-9]+)/g) {
    my ($key, $value) = ($1, $2);
    if (exists $result{$key}) {
        $result{$key}->U($value);

    } else {
        $out->();
        $result{$key} = 'Set::IntSpan'->new($value);
    }
}
$out->();
[download]

Output:

43:1:1-6;27:3:7-9;65:1:4,18;
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.