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 %flatter = map { my $k1 = $_; map { join( qq{\0}, $k1, $_ ), $hoh_test{ $k1 }->{ $_ } } keys %{ $hoh_test{ $k1 } }; } keys %hoh_test; my @sortedKeys = sort { $flatter{ $b } <=> $flatter{ $a } } keys %flatter; printf qq{foo: %s, ba: %s, value: %s\n}, split( m{\0}, $_ ), $flatter{ $_ } for @sortedKeys;