From: Martin Henry H. Stevens <HStevens_at_MUOhio.edu>

Date: Mon 17 Oct 2005 - 20:26:13 EST

"E Pluribus Unum"

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Mon Oct 17 20:38:59 2005

Date: Mon 17 Oct 2005 - 20:26:13 EST

Hi Jose,

I am just beginning to plumb the depths of lattice, but perhaps my
recent experience can help.

I recently figured out (with encouragement from the list) how to plot
predicted values from a model into the appropriate panel. I am
certain that what I have done can be done better, but the following
appears to work for me.

Imagine the model

mod <- lm(Y ~ A + B)

where A is continuous and B is a factor.

I created a new function to use in the panel

panel.modfinal <- function(mod, x, y, subscripts, groups)

xfit <- seq(min(x), max(x), length=21) b <- factor( rep(levels(mod$data$B), rep(21,4)) ) yfit <- predict(mod, newdata=data.frame(A=rep(xfit,4), B=b) ) [b==unique(groups[subscripts] ) ] llines(xfit,yfit,lty=1) }

I then plot the data and the fitted lines with constant slope and unique intercepts:

xyplot(Y ~ A | B, groups=B,

panel=function(x,y, subscripts,groups){ panel.xyplot(x,y) panel.modfinal(mod,x,y,subscripts,groups) } ).

"groups" seems to identify a variable that you want pass to a panel or legend/key function, and subscripts seems to identify the rows used in each panel.

I hope the above is correct and doesn't thereby mislead you, but it seems to work for me.

Hank Stevens

On Oct 14, 2005, at 7:34 PM, Jose Claudio Faria wrote:

> # Dear R list,

*> #
**> # I'm needing help with lattice, regression and respective lines.
**> # My data is below:
**>
**> bra = gl(2, 24, label = c('c', 's'))
**> em = rep(gl(3, 8, label = c('po', 'pov', 'ce')), 2)
**> tem = rep(c(0, 0, 30, 30, 60, 60, 90, 90), 6)
**> tem2 = tem^2
**> r = rep(1:2, 24)
**> y = c(40.58, 44.85, 32.55, 35.68, 64.86, 51.95, 42.52, 52.21,
**> 40.58, 44.85, 33.46, 46.09, 12.75, 18.01, 16.82, 13.69,
**> 40.58, 44.85, 34.45, 29.89, 34.91, 28.10, 27.52, 22.24,
**> 48.68, 47.25, 45.58, 45.33, 41.03, 51.20, 45.85, 54.45,
**> 48.68, 47.25, 19.88, 19.67, 16.20, 13.49, 13.75, 18.80,
**> 48.68, 47.25, 42.19, 39.91, 34.69, 34.11, 32.74, 34.24)
**>
**> Df = data.frame(bra, em, tem, tem2, r, y)
**>
**> # Regressions
**> attach(Df)
**> Dfs1=subset(Df, (bra=='s' & em=='pov'), select=c(bra, em, tem,
**> tem2, r, y))
**> Dfs1
**> rlin1=lm(y ~ tem + tem2, data=Dfs1)
**> summary(rlin1)
**>
**> Dfs2=subset(Df, (bra=='s' & em=='po'), select=c(bra, em, tem, r,
**> y))
**> Dfs2
**> rlin2=lm(y ~ tem, data=Dfs2)
**> summary(rlin2)
**>
**> Dfs3=subset(Df, (bra=='s' & em=='ce'), select=c(bra, em, tem,
**> tem2, r, y))
**> Dfs3
**> rlin3=lm(y ~ tem + tem2, data=Dfs3)
**> summary(rlin3)
**> detach(Df)
**>
**> # I would like to plot with lattice 'y ~ tem | em',
**> # with the panels ('po', 'pov' and 'ce'),
**> # and the its respective regressions lines:
**> # a) linear for panel 'po' or better, without line;
**> # b) quadratic for 'pov' and 'ce'
**>
**> # Is it possible? Could somebody hel me?
**>
**> # I'm trying:
**> library(lattice)
**> attach(Df)
**> Dfs=subset(Df, bra=='s', select=c(bra, em, tem, y))
**> Dfs
**> xyplot(y ~ tem | em,
**> data = Dfs, ylim=c(10, 60), xlim=c(-10, 110),
**> ylab='y', xlab='Time, days',
**> layout = c(3,1))
**> detach(Df)
**>
**> TIA,
**> --
**> Jose Claudio Faria
**> Brasil/Bahia/UESC/DCET
**> Estatistica Experimental/Prof. Adjunto
**> mails:
**> joseclaudio.faria@terra.com.br
**> jc_faria@uesc.br
**> jc_faria@uol.com.br
**> tel: 73-3634.2779
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide! http://www.R-project.org/posting-
**> guide.html
**>
*

Dr. Martin Henry H. Stevens, Assistant Professor
338 Pearson Hall

Botany Department

Miami University

Oxford, OH 45056

Office: (513) 529-4206

Lab: (513) 529-4262

**FAX: (513) 529-4243
**

http://www.cas.muohio.edu/~stevenmh/ http://www.muohio.edu/ecology/ http://www.muohio.edu/botany/

"E Pluribus Unum"

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Mon Oct 17 20:38:59 2005

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