R help - Jan 2008 - how to fit model to split data and get residual plots

I have a data set with the following structure (with many more obs.):

var1 	expt 	day 	diameter
1	1	2	0.5
1	1	3	0.9
1	1	4	1.3
1	1	5	1.7
1	2	2	0.3
1	2	3	0.5
1	2	4	0.9
1	2	5	1.6
2	1	2	0.7
2	1	3	1.2
2	1	4	1.6
2	1	5	2.3
2	2	2	0.4
2	2	3	0.8
2	2	4	1.6
2	2	5	3.2

I can get separate regression analysis for each level of var1 and expt
with the command:

by(data3, data3$var1:data3$expt, function(x) lm(diameter ~ day, data x))

How can I get residual plots for each combination var1*expt generated
above?

Thanks!
Eduardo





-- 
Eduardo S. G. Mizubuti
Departamento de Fitopatologia
Universidade Federal de Vi?osa
36570-000 Vi?osa, MG Brasil
tel.: +55 31 3899 1090
fax: +55 31 3899 2240
e-mail: mizubuti at ufv.br

Try this:

par(mfrow=c(4,4))
lapply(by(data3, list(data3$var1,data3$expt), function(x) lm(diameter
~ day, data = x)), plot)

or:
par(mfrow=c(4,4))
lapply(lapply(split(data3, list(data3$var1, data3$exp)), lm,
form="diameter ~ day"), plot)


On 15/01/2008, Eduardo S. G. Mizubuti <mizubuti at ufv.br>
wrote:
>
> I have a data set with the following structure (with many more obs.):
>
> var1    expt    day     diameter
> 1       1       2       0.5
> 1       1       3       0.9
> 1       1       4       1.3
> 1       1       5       1.7
> 1       2       2       0.3
> 1       2       3       0.5
> 1       2       4       0.9
> 1       2       5       1.6
> 2       1       2       0.7
> 2       1       3       1.2
> 2       1       4       1.6
> 2       1       5       2.3
> 2       2       2       0.4
> 2       2       3       0.8
> 2       2       4       1.6
> 2       2       5       3.2
>
> I can get separate regression analysis for each level of var1 and expt
> with the command:
>
> by(data3, data3$var1:data3$expt, function(x) lm(diameter ~ day, data >
x))
>
> How can I get residual plots for each combination var1*expt generated
> above?
>
> Thanks!
> Eduardo
>
>
>
>
>
> --
> Eduardo S. G. Mizubuti
> Departamento de Fitopatologia
> Universidade Federal de Vi?osa
> 36570-000 Vi?osa, MG Brasil
> tel.: +55 31 3899 1090
> fax: +55 31 3899 2240
> e-mail: mizubuti at ufv.br
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O