$ perl -e'
my %hoh = (
    FILENAME1 => { A => { weight => 3000, intensity => 2 },
                   B => { weight => 4000, intensity => 3 } },
    FILENAME2 => { D => { weight => 2000, intensity => 7 },
                   C => { weight => 5000, intensity => 3 } },
    FILENAME3 => { C => { weight => 1000, intensity => 4 },
                   A => { weight => 6000, intensity => 3 } },
    );

print map "weight: $_->[0] intensity: $_->[1] Filename: $_->[2]\n",
      map [ unpack q[NNA*], $_ ],
      sort
      map {
          my $file = $_;
          map pack( q[NNA*], @{$hoh{$file}{$_}}{qw/weight intensity/},
+ $file ), keys %{ $hoh{ $file } }
          }
      keys %hoh;
'
weight: 1000 intensity: 4 Filename: FILENAME3
weight: 2000 intensity: 7 Filename: FILENAME2
weight: 3000 intensity: 2 Filename: FILENAME1
weight: 4000 intensity: 3 Filename: FILENAME1
weight: 5000 intensity: 3 Filename: FILENAME2
weight: 6000 intensity: 3 Filename: FILENAME3
[download]