in reply to 'rewinding' file to get value from previous line in file?

This should get you where you want to go:

#!/usr/bin/perl 
use strict;

my @Z;
my $last_stop;
while (<DATA>) {
    chomp;
    my @token = split ' ';
    if ( $token[0] eq 'Z' ) {
        if ($token[1] == $last_stop + 1) {
            $Z[-1]->[1] = $token[2];
        } else {
            push @Z, [ @token[1,2] ];
        }
        $last_stop = $token[2];
    }
}

print Dumper(\@Z);

__DATA__
Z  5   89
Z  92  102
Z  103 123
Z  126 150

[download]
-sauoq
"My two cents aren't worth a dime.";

Replies are listed 'Best First'.
Re^2: 'rewinding' file to get value from previous line in file?
by ikegami (Patriarch) on Dec 07, 2006 at 19:00 UTC
    • $last_stop gives an undefined warning.
    • $last_stop can be replaced with $Z[-1][1].
    • chomp is redundant.
    • The if is fine as it is, but the common $Z[-1][1] = $token[2] can be factored out. 
    my @Z;
while (<DATA>) {
    my @token = split ' ';
    if ( $token[0] eq 'Z' ) {
        push @Z, [ $token[1] ]
           if !$Z[-1] || $token[1] != $Z[-1][1] + 1;
        $Z[-1][1] = $token[2];
    }
}

    [download]
[reply]
[d/l]
[select]
    A reply falls below the community's threshold of quality. You may see it by logging in.

In Section Seekers of Perl Wisdom