[Bioperl-l] Xyplot and multiple lines plots

[Emanuele Osimo]

Hello everyone,
I would like to plot two data sets in Bio::Graphics using Xyplot, one
superimposed on the other.
I need to compare the differential expression of an Affy expression
probeset  in different subjects.
I successfully managed to plot one at a time with:
$panel->add_track(    $feat,
                                -graph_type=>'linepoints',
                                -glyph =>'xyplot',
                                -fgcolor=>'gray',
                                -max_score    => 1,
                                -min_score    => 0,
                                );
But I cannot understand how to plot two lines independently in the same
track.

Thank you in advance,
Emanuele