my @flat_data;

for my $file (keys %hoh){
  for my $letter (keys %{$hoh{$file}}){
    my $weight    = $hoh{$file}{$letter}{weight};
    my $intensity = $hoh{$file}{$letter}{intensity};
    push @flat_data, 
      "weight: $weight intensity $intensity Filename: $file";
  }
}

print "$_\n" for sort @flat_data;