my @array_of_objects = (
	{ sex=>'Male', occupation=>'foo' },
	{ sex=>'Female', occupation=>'foo' },
	{ sex=>'Male', occupation=>'bar' },
	{ sex=>'Female', occupation=>'bar' },
	{ sex=>'Female', occupation=>'foo' },
);

my %counts;
$counts{ $_->{sex} }++ for @array_of_objects;

my %grouped;
$grouped{ $_->{sex} }{ $_->{occupation} }++ for @array_of_objects;

use Data::Dumper;
print Dumper( \%counts, \%grouped );

__END__

$VAR1 = { 'Female' => 3, 'Male' => 2 };
$VAR2 = { 'Female' => { 'bar' => 1, 'foo' => 2 },
          'Male' => { 'foo' => 1, 'bar' => 1 } };

##</code><code>##

sub count {
	my ($data, $fields) = @_;
	$fields = [$fields] unless ref $fields;
	my $count = {};
	_dive( $count, $_, @$fields ) for @$data;
	return $count;
}
sub _dive {
	my ($ref, $obj, @path) = @_;
	my $targ = \$ref->{ $obj->{ shift @path } };
	if (!@path) { $$targ++; return $ref }
	$$targ = _dive( $$targ, $obj, @path );
}

print Dumper( count(\@array_of_objects, 'sex') );
print Dumper( count(\@array_of_objects,
	['sex','occupation']) );