[R] Re gression for levels of a factor/xyplot type="r"

[jimdare]

Hi,  

I'm sure these are basic problems so I apologise in advance for my
ignorance.  I have a dataset with X, Y, and a Factor with 4 levels.  I am
trying to figure out how to use lm() to find the r2 value, slope and
intercept of an X~Y regression, for each level of the Factor.  Is there a
way to do this automatically without having to specify different subsets of
the factor?

my code so far:

Regression<-lm(Y~X, data=dataset, subset=factor(Factor))

Also, when I plot this dataset using:

xyplot(Y~X|factor(Factor), data=dataset, aspect="iso",
type=c("p","g","r"),pch=21,cex=1)

I get a four panel plot (one for each level of the factor) with a regression
line for each.  How do I figure out the r2 value and coefficients of each
regression line and add them as text to the plot.   

Thanks for your help!

James



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