[R] Doubt Linear Regression

Chuck Cleland
Thu, 05 Mar 2009 13:08:13 -0000

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
>
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Chuck Cleland, Ph.D.
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