Here's one way to do it. I'm creating a hash of hashes, where the elements of the inner hash are array references (so a hash of arrays). This means that for vgs that all have the same maj_num, the hash should only have one key, whereas if the maj_nums are different, there's more than one key. The output generation uses join, map, and de-referencing operations (see perlreftut and perlref).

use warnings;
use strict;
use Data::Dump;  # debug

my @vgmap = (
    { node => "node1", vg => "vg1", maj_num => 36 },
    { node => "node2", vg => "vg1", maj_num => 36 },
    { node => "node1", vg => "vg2", maj_num => 37 },
    { node => "node2", vg => "vg2", maj_num => 37 },
    { node => "node1", vg => "vg3", maj_num => 38 },
    { node => "node2", vg => "vg3", maj_num => 40 },
);

my %vgmap;
for my $vgm (@vgmap) {
    push @{ $vgmap{ $vgm->{vg} }{ $vgm->{maj_num} } }, $vgm->{node};
}
dd \%vgmap;  # debug

for my $vg (sort keys %vgmap) {
    my @maj_nums = sort keys %{ $vgmap{$vg} };
    if ( @maj_nums != 1 ) {
        print "$vg: ", join( "; ",
            map { "$_ used on "
                . join ", ", @{ $vgmap{$vg}{$_}} } @maj_nums
            ), "\n";
    }
}

__END__

{
  vg1 => { 36 => ["node1", "node2"] },
  vg2 => { 37 => ["node1", "node2"] },
  vg3 => { 38 => ["node1"], 40 => ["node2"] },
}
vg3: 38 used on node1; 40 used on node2

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In reply to Re: Compare the values in the hash by haukex
in thread Compare the values in the hash by perl_5eeker

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