R help - Jan 2010 - control of scat1d tick color in plot.Predict?

Hi All,

I have a quick question about using plot.Predict now that the rms package
uses lattice.  I'd like to add tick marks along the regression line, which
is given by data=llist(variablename) in the plot call.  The ticks show up
fine, but I'd like to alter the color.  I know the ticks are produced by
scat1d, but after spending a fair bit of time going through documentation,
it still isn't clear to me how to do this in the context of lattice.
Guidance would be greatly appreciated.

Thanks,

Mike Babyak
Duke University Medical Center

My code using R 2.10.1/windows XP

myx<-c(1,2,3,4)
myy<-c(1,2,3,5)

library(rms)

d<-datadist(myx)
options(datadist="d")

myfit<-ols(myy~myx,x=T,y=T)

p1<-Predict(myfit,myx =.)

library(lattice)

#change line to black
line <- trellis.par.get("plot.line")
line$col <- 1
trellis.par.set("plot.line", line)

plot(p1, data=llist(myx),col.fill="lightgray", lwd=1.5)

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Mike Babyak wrote:
> Hi All,
> 
> I have a quick question about using plot.Predict now that the rms package
> uses lattice.  I'd like to add tick marks along the regression line,
which
> is given by data=llist(variablename) in the plot call.  The ticks show up
> fine, but I'd like to alter the color.  I know the ticks are produced
by
> scat1d, but after spending a fair bit of time going through documentation,
> it still isn't clear to me how to do this in the context of lattice.
> Guidance would be greatly appreciated.
> 
> Thanks,
> 
> Mike Babyak
> Duke University Medical Center
> 
> My code using R 2.10.1/windows XP
> 
> myx<-c(1,2,3,4)
> myy<-c(1,2,3,5)
> 
> library(rms)
> 
> d<-datadist(myx)
> options(datadist="d")
> 
> myfit<-ols(myy~myx,x=T,y=T)
> 
> p1<-Predict(myfit,myx =.)
> 
> library(lattice)
> 
> #change line to black
> line <- trellis.par.get("plot.line")
> line$col <- 1
> trellis.par.set("plot.line", line)
> 
> plot(p1, data=llist(myx),col.fill="lightgray", lwd=1.5)
That's a good request.  I've added a new argument scat1d.opts to 
plot.Predict in rms.  Default is list(frac=0.025, lwd=0.3) with col 
computed.  If you specify col inside the list, it will be used. 
source('http://biostat.mc.vanderbilt.edu/tmp/plot.Predict.s') to get the
new version.

Frank

-- 
Frank E Harrell Jr   Professor and Chairman        School of Medicine
                      Department of Biostatistics   Vanderbilt University