R help - Nov 2010 - Add values of rlm coefficients to xyplot

Hello,

I have a simple xyplot with rlm lines.
I would like to add the a and b coefficients (y=ax+b) of the rlm calculation
in each panel.
I know I can do it 'outside' the xyplot command but I would like to do
all
at the same time. 

I found some posts with the same question, but no answer.

Is it impossible ?

Thanks in advance for your help.
Ptit Bleu.

x11(15,12)
xyplot(df1$col2 ~ df1$col3 | df1$Name,
panel = function(x, y,...) {
                panel.abline(h=seq(20,40,5), col="gray")
                panel.abline(v=seq(-10,60,5), col="gray")
                panel.xyplot(x, y, type="p", col="red",
pch=20,...)
                panel.abline(rlm(y ~ x), col="blue")
                }, scales=list(cex=1.2),
                 xlab=list("X", cex=1.4), ylab=list("Y",
cex=1.4),
xlim=c(-10,60), ylim=c(20,40))

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Hello again,

Thanks to this forum, I found a lapply command to apply "rlm" to each
Device
of the Name column of the df1 data frame (df1 data frame is given in the
previous post).

I'm now looking for a nice way to create a data frame with the name of the
device, the intercept and the slope. I now use a for loop (see below) but
I'm sure there is a more elegant way to retrieve these coefficients,
isn't
it ?

Thanks in advance for your help to improve this script.
Ptit Bleu.

# Library including rlm
library(MASS)
# To apply rlm to each Device of df1$Name
bbb<-lapply(split(df1, df1$Name), function(X)(rlm(col2 ~ col3, data=X)})

# To get Intercept and Slope for each device
dfrlm1<-data.frame()
for (u in 1:length(names(bbb))) {
dfrlm1<-rbind(dfrlm1, data.frame(as.character(names(bbb)[u]),
bbb[[u]][[1]][[1]], bbb[[u]][[1]][[2]]))
}
names(dfrlm1)<-c("Name", "Intercept", "Slope")

# To plot the graphs and display the rlm coefficients
x11(15,12)
xyplot(df1$col2 ~ df1$col3 | df1$Name,
panel = function(x, y,...) {
                panel.abline(h=seq(20,30,1), col="gray")
                panel.abline(v=seq(20,70,5), col="gray")
                panel.xyplot(x, y, type="p", col="red",
pch=20,...)
                panel.abline(rlm(y ~ x), col="blue")
                panel.text(40,21, paste("y =",
round(dfrlm1$Intercept[panel.number()],3),"+ (",
round(dfrlm1$Slope[panel.number()],3),") *x"))
                }, scales=list(cex=1.2),
                 xlab=list("X", cex=1.4), ylab=list("Y",
cex=1.4),
xlim=c(20,70), ylim=c(20,30))

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