sub get_hotspot
{
	my $self = shift;
	my $ds = shift;		# Which data set
	my $np = shift;		# Which data point?

	if (defined $np && defined $ds)
	{
		return @{$self->{_hotspots}->[$ds]->[$np]};
	}
	elsif (defined $ds)
	{
		return @{$self->{_hotspots}->[$ds]};
	}
	else
	{
		return @{$self->{_hotspots}};
	}
}