I think the first thing to make more elegant was the initialisation of %hoh to save some of the repeat typing and eliminate the key quoting. For the sorting I have tried a Schwartzian Transform but I wouldn't say it was particularly elegant because you have to jump through hoops to get at the second-level keys.

use strict;
use warnings;

my %hoh;

$hoh{FILENAME1} =
   {
      A => {weight => 3000, intensity => 2},
      B => {weight => 4000, intensity => 3},
   };

$hoh{FILENAME2} =
   {
      C => {weight => 5000, intensity => 3},
      D => {weight => 2000, intensity => 7},
   };

$hoh{FILENAME3} =
   {
      A => {weight => 6000, intensity => 3},
      C => {weight => 1000, intensity => 4},
   };

print
   map
   {
       sprintf qq{weight %d intensity %d Filename %s\n},
          $hoh{$_->[0]}->{$_->[1]}->{weight},
          $hoh{$_->[0]}->{$_->[1]}->{intensity},
          $_->[0];
   }
   sort
   {
       $hoh{$a->[0]}->{$a->[1]}->{weight}
       <=>
       $hoh{$b->[0]}->{$b->[1]}->{weight}
   }
   map
   {
       my $item = $_;
       my @keyPairs;
       push @keyPairs, [$item, $_]
          for keys %{$hoh{$_}};
       @keyPairs;
   }
   keys %hoh;

[download]

This produces the desired output

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]

I hope this is of interest.

Cheers,

JohnGG

Update: Changed array @keyList to more meaninfully named @keyPairs in map.

In reply to Re: HoH problem by johngg
in thread HoH problem by tamaguchi

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