R help - Jan 2009 - Problem between panel.abline and log scales (lattice)

Hello and Happy New Year to all R-Users !!!

I would like to plot a lattice graph with a logarthmic y axis and add two
reference lines that is :

ref<-c(0.0070, 0.0096)

graph1<-xyplot(data$y1 ~ as.numeric(strptime(data$x1, format="%Y-%m-%d
%H:%M:%S")) | as.character(data$Code),
list(y = list(log = T)),
xlab="X'", ylab="Y",
panel = function(...) {
                panel.xyplot(..., type="p", pch=20)
                panel.abline(h=ref, col="red")
               }

)
 print(graph1)
 

With this script, no reference lines are plotted.
But if I use list(y = list(log = F)), that is a linear scale, it works.

Could you please explain me the problem (and help me to solve it) ?
Thanks in advance,
Ptit Bleu. 
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On 1/12/09, Ptit_Bleu <ptit_bleu at yahoo.fr>
wrote:
>
>  Hello and Happy New Year to all R-Users !!!
>
>  I would like to plot a lattice graph with a logarthmic y axis and add two
>  reference lines that is :
>
>  ref<-c(0.0070, 0.0096)
>
>  graph1<-xyplot(data$y1 ~ as.numeric(strptime(data$x1,
format="%Y-%m-%d
>  %H:%M:%S")) | as.character(data$Code),
>  list(y = list(log = T)),
>  xlab="X'", ylab="Y",
>  panel = function(...) {
>                 panel.xyplot(..., type="p", pch=20)
>                 panel.abline(h=ref, col="red")
>                }
>
>  )
>   print(graph1)
>
>
>  With this script, no reference lines are plotted.
>  But if I use list(y = list(log = F)), that is a linear scale, it works.
>
>  Could you please explain me the problem (and help me to solve it) ?
xyplot(y ~ x, scales=list(log=TRUE))

is basically equivalent to

xyplot(log10(y) ~ log10(x))

(plus some changes to axis annotation). You will probably need to use
panel.curve instead of panel.abline in your panel function.

-Deepayan