R help - Sep 2011 - Adding groups to regression line panel function in Lattice

I wish to display a single-panel Lattice figure with grouped data and fitted
regression lines. I don't seem to be able to get the
individual regression lines to display, e.g.;

d <- data.frame(q = rep(1:6, each=10), cc = rep(seq(10,100, 10),6))          
# create data frame with group identifier 'q', independent variable cc
d$ba = d$q*0.1*d$cc + 5*rnorm(nrow(d))                                          
# create dependent variable 'ba'

mypanel <- function(...){                                                    
# panel function
                panel.lmline(d$cc, d$ba, groups = d$q)                          
#
                panel.xyplot(...)
                }

xyplot(ba~cc,d,
                groups=q,
                panel = panel.superpose,
                panel.groups=mypanel
                )

Can anyone suggest how to get lines to display by group? (and how to get lmline
panel to fit line without estimating an intercept?)


Seth W. Bigelow, Ph.D.
Research Ecologist
USDA-FS Pacific Southwest Research Station


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On Fri, Sep 9, 2011 at 9:38 PM, Bigelow, Seth <sbigelow at fs.fed.us>
wrote:
> I wish to display a single-panel Lattice figure with grouped data and
fitted regression lines. I don't seem to be able to get the
> individual regression lines to display, e.g.;
>
> d <- data.frame(q = rep(1:6, each=10), cc = rep(seq(10,100, 10),6)) ? ?
? ? ? ? ? ? ? ? ? ? ?# create data frame with group identifier 'q',
independent variable cc
> d$ba = d$q*0.1*d$cc + 5*rnorm(nrow(d)) ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? # create dependent variable 'ba'
>
> mypanel <- function(...){ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?# panel function
> ? ? ? ? ? ? ? ?panel.lmline(d$cc, d$ba, groups = d$q) ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?#
> ? ? ? ? ? ? ? ?panel.xyplot(...)
> ? ? ? ? ? ? ? ?}
But panel.lmline() does not honour a 'groups' argument, so there is no
reason for this to work.
> xyplot(ba~cc,d,
> ? ? ? ? ? ? ? ?groups=q,
> ? ? ? ? ? ? ? ?panel = panel.superpose,
> ? ? ? ? ? ? ? ?panel.groups=mypanel
> ? ? ? ? ? ? ? ?)
>
> Can anyone suggest how to get lines to display by group?
How about

xyplot(ba~cc,d, groups=q, type=c("p", "r"))
> (and how to get lmline panel to fit line without estimating an intercept?)
xyplot(ba~cc,d, groups=q, panel = panel.superpose,
       panel.groups = function(x, y, ...) {
           panel.xyplot(x, y, ...)
           panel.abline(0, coef(lm(y ~ 0 + x)), ...)
       })

-Deepayan