[R] Lattice xyplot help please.

[Haoda Fu]

Hi -

I am not R expert and I would appreciate your time if you can help me
about my xyplot question.

I would like to add text (p-value) in a 4 panels xyplot. I thought
panel = function{} should work but I am not sure where I did it wrong.

The error message from the following code is 
"Argument subscripts is missing with no default values"

xyplot(GLG ~ PD | factor(TRT) , groups = GLG_ind,strip = strip.custom(style =4),ref = T, as.table=TRUE,data = splitPD,  subscripts = TRUE,cex = 2, 
panel = function(x, y, pvalue,subscripts,...){
   panel.xyplot(x,y,...); 
   panel.abline(h = 51.95);
   grid.text(paste("p-value =", pvalue[subscripts]), .25, .15,
            gp = gpar(cex = .8))}
)


I really appreciate your time to help me. 

Best,
Haoda


Appendix -

Data
> pvalue
[1] 0.88313298 0.02224550 0.80000000 0.12663046

> splitPD
    PD TRT  GLG GLG_ind
1   -8  30 38.5       0
2  -81  30 58.6       1
4  -33  30 35.0       0
5  -18  30 41.1       0
6  -45  90 64.3       1
8  -39  90 41.9       0
9  -45  90 56.2       1
10 -98  90 53.6       1
11  27  90 46.4       0
12 -45  90 74.2       1
15 -22   5 56.4       1
16 -25   5 63.8       1
17   4   5 50.2       0
18 -52  30 64.6       1
21 -31  60 44.5       0
22 -36   5 42.1       0
23 -56   5 37.8       0
24  -5   5 31.3       0
26 -29   5 31.7       0
27  -9   5 39.0       0
28  -9   5 26.7       0
31 -41  30 52.7       1
32 -24  30 50.4       0
33 -18  30 32.4       0
35 -36  30 41.3       0
36 -22  30 41.1       0
37 -36  90 42.5       0
39 -18  90 63.9       1
40 -25  60 40.6       0
42 -43  60 86.4       1
43 -58  60 48.1       0
44 -16  60 48.5       0
45 -26  60 59.2       1

Code works
rm(list=ls());
library(lattice);
library(grid);
library(rpart);
xyplot(GLG ~ PD | factor(TRT) , groups = GLG_ind,strip = strip.custom(style =4),ref = T, as.table=TRUE,data = splitPD,  cex = 2, panel = function(x, y,...){panel.xyplot(x,y,...); panel.abline(h = 51.95); })