#!/usr/bin/perl
use strict;
use warnings;
use Sort::Key qw(ikeysort);

my %hoh;

$hoh{'FILENAME1'}{'A'}{'weight'}=3000;
$hoh{'FILENAME1'}{'A'}{'intensity'}=2;

$hoh{'FILENAME1'}{'B'}{'weight'}=4000;
$hoh{'FILENAME1'}{'B'}{'intensity'}=3;

$hoh{'FILENAME2'}{'D'}{'weight'}=2000;
$hoh{'FILENAME2'}{'D'}{'intensity'}=7;

$hoh{'FILENAME2'}{'C'}{'weight'}=5000;
$hoh{'FILENAME2'}{'C'}{'intensity'}=3;

$hoh{'FILENAME3'}{'C'}{'weight'}=1000;
$hoh{'FILENAME3'}{'C'}{'intensity'}=4;

$hoh{'FILENAME3'}{'A'}{'weight'}=6000;
$hoh{'FILENAME3'}{'A'}{'intensity'}=3;



# Create a list of sets
# $set[0] = filename
# $set[1] = letter
# $set[2] = reference to the data for this filename-letter combination
my @sets;
for my $filename (keys %hoh) {
    push @sets, [$filename, $_,$hoh{$filename}{$_}] for keys %{$hoh{$filename}}
}
for my $set (ikeysort { $_->[2]{weight} } @sets) {
    my ($filename,$letter,$data) = @$set;
    my $weight    = $data->{weight};
    my $intensity = $data->{intensity};
    printf "weight: %4d intensity: %d Filename: %s\n",$weight,$intensity,$filename;
}