[R] Problems with graphics

[Christophe Nguyen]

Dear all,
I am a SAS user, who's trying R. I am a little bit lost for graphics. 
What is the simplest way for plotting y as a function of x with one 
symbol (line or dot) for each level of a class variable z (for SAS 
langage= plot x*y=z). Can I add vertical bars for standard deviation 
stored in a  separate variable (say  ystd). Finally, is it possible to 
do all this with xyplot function arranging plots according to A and B 
factor: xyplot(y~x|A*B) with as many plots and symbol as there is levels 
in the z variable for each panel?
Thanks for the help.
Chris

-- 
___________________________________________________

Christophe NGUYEN

UMR 1220 INRA-ENITAB
Transfert sol-plante et cycle des éléments minéraux
dans les écosystèmes cultivés"

Centre INRA de Bordeaux-Aquitaine
71, avenue Edouard Bourlaux, BP 81
33883 Villenave d'Ornon, FRANCE

Tel : 00 33 (0)5 57 12 25 07
Fax : 00 33 (0)5 57 12 25 15

email : Christophe.Nguyen at bordeaux.inra.fr
page infoservice: http://www.bordeaux.inra.fr/tcem

__________m°O°m____________________________________