Join unless $var has already been joined?

blink has asked for the wisdom of the Perl Monks concerning the following question:

Given the code below, I'd like to perform the join, only if the variable hasn't already been joined.

When I dump the hash that this script creates, the inner hash, "tapes" can have duplicate values. I'll post some output to illustrate. I want only unique (in this case) tape id's to be included.

#!/opt/openv/perl/bin/perl -w

use strict;
use Data::Dumper;
use NBUX;
my %images = bpimagelist();

#print Dumper(\%images);
#exit;

my (%status);

foreach my $key (sort keys %images)
{

        my ($tapes, $img);

        my $client     = $images{$key}->{'client'};
        my $sched_type = $images{$key}->{'schedule_type'};
        my $sched_name = $images{$key}->{'sched_label'};
        my $policy     = $images{$key}->{'policy'};
        my $kb         = $images{$key}->{'kbytes'};

    foreach my $key2 (sort keys %{$images{$key}})
    {

        if ($key2 =~ /copy_\d_frag_\d_id/)
        {
            $img   = $images{$key}{$key2};

            $tapes = (join (' ', $img, $tapes));
            $status{$client}{$policy}{'tapes'} = $tapes;

        }

    }

}

#print Dumper(\%status);
#exit;
[download]

Here's some example output that I'm trying to avoid:

$VAR1 = {
          'bondsrv1' => {
                      'acis_misc_os' => {
                                 'tapes' => 'OK0238 OK0238 '          
+                                                              

                        }               },
        }
[download]

Comment on Join unless $var has already been joined? Select or Download Code

Replies are listed 'Best First'.
Re: Join unless $var has already been joined? by sgifford (Prior) on Sep 23, 2003 at 20:58 UTC
What you want is to eliminate duplicate elements from a list. Here's one solution, from the Perl cookbook (via RE: Return a Unique Array): `my %seen =() ; @unique_array = grep { ! $seen{$_}++ } @non_unique_array ;` [download] Put that into a sub: `sub dedup { my %seen; grep { ! $seen{$_}++ } @_; }` [download] and you can simply do `@tapes = qw(tape1 tape2 tape1 tape3 tape2 tape1); print join(' ',dedup(@tapes)),"\n";` [download] to join tapes together with no duplicates.	[reply] [d/l] [select]
Re: Join unless $var has already been joined? by Roger (Parson) on Sep 24, 2003 at 00:29 UTC
Replace your foreach loop with this instead - foreach my $key (sort keys %images) { my ($tapes, $img); my $client = $images{$key}->{'client'}; my $sched_type = $images{$key}->{'schedule_type'}; my $sched_name = $images{$key}->{'sched_label'}; my $policy = $images{$key}->{'policy'}; my $kb = $images{$key}->{'kbytes'}; # Create an array of tape records my @tapes; foreach (keys %{$images{$key}) { if (/copy_\d_frag_\d_id/) { push @tapes, $images{$key}{$_}; } } # Join tape id's in sorted order $status{$client}{$policy}{'tapes'} = join " ", sort keys %{{map {$_=>1} @tapes}}; } [download]	[reply] [d/l]