G'day Special_K,

Your basic problem is not taking into account the fact that hashes are unordered. You'll get foo1, foo2 & foo3 returned in a random order when you call keys %hoh_test; and, for each of those, you'll get bar & baz returned in a random order when you call keys %{$hoh_test{$foo}}.

Here's my take on a solution:

#!/usr/bin/env perl

use strict;
use warnings;

my %hoh_test = (
    foo1 => { bar => -0.12697, baz => -0.000398154 },
    foo2 => { bar => -4.0183e-05, baz => 0 },
    foo3 => { bar => 9.966003977e-06, baz => 0.0001939 },
);

my @hoh_data;

for my $k0 (keys %hoh_test) {
    for my $k1 (keys %{$hoh_test{$k0}}) {
        push @hoh_data, [$k0, $k1, $hoh_test{$k0}{$k1}];
    }
}

my $fmt = "foo: %s, ba: %s, value: %s\n";
printf $fmt, @$_ for sort { $b->[2] <=> $a->[2] } @hoh_data;
[download]

This produces the same output on each run:

foo: foo3, ba: baz, value: 0.0001939
foo: foo3, ba: bar, value: 9.966003977e-06
foo: foo2, ba: baz, value: 0
foo: foo2, ba: bar, value: -4.0183e-05
foo: foo1, ba: baz, value: -0.000398154
foo: foo1, ba: bar, value: -0.12697
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Just to exemplify the unordered nature of hashes, here's what @hoh_data looked like, on two separate runs, before passing to sort { $b->[2] <=> $a->[2] }:

(
  ["foo1", "bar", -0.12697],
  ["foo1", "baz", -0.000398154],
  ["foo2", "baz", 0],
  ["foo2", "bar", -4.0183e-05],
  ["foo3", "baz", 0.0001939],
  ["foo3", "bar", 9.966003977e-06],
)
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(
  ["foo1", "baz", -0.000398154],
  ["foo1", "bar", -0.12697],
  ["foo3", "baz", 0.0001939],
  ["foo3", "bar", 9.966003977e-06],
  ["foo2", "bar", -4.0183e-05],
  ["foo2", "baz", 0],

)
[download]

Update: Well, I made a real mess of keys %{hoh_test($foo}}. Now fixed: keys %{$hoh_test{$foo}}.