R help - May 2006 - adding grid lines to an xyplot when there is only 1 panel - corrected

Sorry, some things got garbled in that request for help that might make 
my request
unintelligible, probably it being too late at night when I posted, here 
is the corrected function
call for which I would like to learn how to add horizontal grid lines.  
Any suggestions
would be appreciated.  Apologies for the posting error

xyplot(est ~ STE, data = all, groups = AREA, type = "b",
   		auto.key = list(space = "right"))

For the record, I'm working with Mac OS X 10.4.6 with R 2.3

Thank you.
> I've been struggling with this for a while and cannot get it to work.
> Is there a simple way to add grid lines ---- I'd like to only add the
> horizontal ones --- when using the groups argument in xyplot?
> I can get the grid lines to plot, or the points/lines, but not both.
> Here is a simple example of the sort of thing that I'm working with.
> Thanks, in advance.
>
>  >all
>        est  STE AREA
>    -0.229    V1   V1
>    -1.129    V1   V2
>    -2.084    V1   V4
>    -2.918    V1   V3
>    -0.548    V2   V1
>    -0.217    V2   V2
>    -1.937    V2   V3
>    -1.205    V2   V4
>    -4.126    V4   V1
>    -1.481    V4   V2
>    -2.070    V4   V3
>    -0.042    V4   V4
>
> xyplot(est ~ ISITE, data = all2, groups = AREA, type = "b",
>   		auto.key = list(space = "right"))
>
Ken Knoblauch

-- 
Ken Knoblauch
Inserm U371
Cerveau et Vision
Dept. of Cognitive Neuroscience
18 avenue du Doyen L?pine
69500 Bron
France
tel: +33 (0)4 72 91 34 77
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http://www.lyon.inserm.fr/371/

On 5/18/06, ken knoblauch <knoblauch at lyon.inserm.fr>
wrote:
> Sorry, some things got garbled in that request for help that might make
> my request
> unintelligible, probably it being too late at night when I posted, here
> is the corrected function
> call for which I would like to learn how to add horizontal grid lines.
> Any suggestions
> would be appreciated.  Apologies for the posting error
>
> xyplot(est ~ STE, data = all, groups = AREA, type = "b",
>    		auto.key = list(space = "right"))
Write your own panel function, e.g.

xyplot(est ~ STE, data = all, groups = AREA, type = "b",
       panel = function(...) {
           panel.grid(h = -1, v = 0)
           panel.xyplot(...)
       },
       auto.key = list(space = "right"))

See ?panel.grid for more options.

Deepayan