[R] Doubt Linear Regression

[Chuck Cleland]

On 3/5/2009 7:53 AM, Sueli Rodrigues wrote:
> 
> Hello. I have a file with 480 lines but each 6 lines corresponding just
> one sample. How can can work out the linear regression to each 6 lines?
> I use the model: model=lm(y~x)

mydf <- data.frame(X = rnorm(480), Y = rnorm(480))
mydf$SAMPLE <- rep(1:80, each=6)

by(mydf, mydf$SAMPLE, function(x){summary(lm(Y ~ X, data = x))})

OR

lapply(split(mydf, mydf$SAMPLE), function(x){summary(lm(Y ~ X, data = x))})

OR

library(nlme)

fm1 <- lmList(Y ~ X | SAMPLE, mydf)
summary(fm1)

> Sueli Rodrigues
> 
> Agronomy Eng. - UNESP
> Master Degree - USP/ESALQ
> PPG-Soils and Plants Nutrition
> Phones(19)93442981
>       (19)33719762
> 
> ______________________________________________
> 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. 

-- 
Chuck Cleland, Ph.D.
NDRI, Inc. (www.ndri.org)
71 West 23rd Street, 8th floor
New York, NY 10010
tel: (212) 845-4495 (Tu, Th)
tel: (732) 512-0171 (M, W, F)
fax: (917) 438-0894