[R] Multipanel weighted regression lines.

[Kevin Brown]

Dear R-users,

I am trying to create a multipanel scatter plot which displays weighted 
regression lines for each subgroup. I am having diffuculty figuring out 
how the Trellis multipanel plotting functions work, in general. Does 
someone know where there are some beginners examples on how to create 
and use  panel.xxx functions in conjunction with the xyplot functions?

Back to the matter at hand - There are two different ways that I could 
add these lines, I think.

The first, and simplest would be to first find the coeffecients of the 
weighted regression line for each panel ( I can do this). Then I would 
add these coeffecients into a vector/matrix (i'm not sure what form of 
vector would be suitable) and add them to each panel (I do not know how 
to do this).

The second way would be to fiddle around with the function below to add 
the "weights" to the lm function call. I do not know how to change this 
"plot.regression" function to do that.

plot.regression = function(x,y)
{
panel.xyplot(x,y)
panel.abline(lm(y~x))
}

xyplot(yg~xg | g, panel="plot.regression")

Any help would be great!
Thanks,
Kevin Brown.