use warnings;
use strict;
use Data::Dumper;

my %rankBased = (
	190 => {
		test1 => { score => '13.28'  },
		test2 => { score => '-47.56' },
		test3 => { score => '18.50'  },
		test4 => { score => '14.88'  },
	},
	191 => {
		test1 => { score => '9.18'  },
		test2 => { score => '2.84'  },
		test3 => { score => '15.62' },
		test4 => { score => '11.84' },
	},
);

for my $key1 (keys %rankBased) {
	my @sort_by_rank = sort {
		$rankBased{$key1}{$b}{score} <=> $rankBased{$key1}{$a}{score}
			} keys %{$rankBased{$key1}};
	print Dumper(\@sort_by_rank);
}

__END__

$VAR1 = [
          'test3',
          'test4',
          'test1',
          'test2'
        ];
$VAR1 = [
          'test3',
          'test4',
          'test1',
          'test2'
        ];