[R] repeat a linear regression model

[arun]

Hi,
Try:
Please use ?dput() to show the example dataset:


dat <- structure(list(ID = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), Y = c(555L, 
345L, 456L, 552L, 342L, 452L, 555L, 345L, 456L, 552L, 342L, 452L, 
562L, 352L, 463L, 582L, 342L, 483L, 522L, 362L, 493L, 532L, 342L, 
423L), X1 = c(111L, 234L, 353L, 115L, 232L, 358L, 111L, 234L, 
353L, 115L, 232L, 358L, 118L, 251L, 320L, 138L, 211L, 320L, 128L, 
221L, 320L, 119L, 242L, 330L), X2 = c(222L, 445L, 453L, 222L, 
449L, 458L, 222L, 445L, 453L, 222L, 449L, 458L, 239L, 422L, 470L, 
219L, 422L, 410L, 239L, 492L, 470L, 219L, 432L, 460L), X3 = c(333L, 
543L, 456L, 343L, 524L, 458L, 333L, 543L, 456L, 343L, 524L, 458L, 
340L, 540L, 473L, 310L, 520L, 453L, 310L, 530L, 483L, 320L, 530L, 
413L), X4 = c(456L, 33L, 333L, 486L, 23L, 348L, 456L, 33L, 333L, 
486L, 23L, 348L, 463L, 40L, 330L, 423L, 43L, 310L, 433L, 45L, 
310L, 433L, 41L, 340L)), .Names = c("ID", "Y", "X1", "X2", "X3", 
"X4"), class = "data.frame", row.names = c(NA, -24L))


 res <- t(sapply(split(dat[,-1],dat$ID),function(x) coef(lm(Y~.,data=x))[-1]))
 colnames(res) <- letters[1:4]


#or

library(plyr)

 res1 <- ddply(dat,.(ID),function(x) coef(lm(Y~.,data=x[,-1])))[,-2]
 colnames(res1)[-1] <- colnames(res)


#or

res3 <- do.call(rbind,by(dat[,-1],dat[,1],function(x) coef(lm(Y~.,data=x))[-1]))
 colnames(res3) <- colnames(res)


A.K.




On Monday, October 14, 2013 1:00 PM, Valeria Muzzolini <valeria.muzzolini at uniud.it> wrote:
Hello,
I'd like to repeat a linear regression model for groups of rows that are 
identified by an ID number.
My table is like this:
ID     Y     X1     X2     X3     X4
1     555     111     222     333     456
1     345     234     445     543     33
1     456     353     453     456     333
2     562     118     229     340     463
2     352     241     452     550     40
2     463     360     460     463     340
3     ....
    ...
    ...
    ...
    ....
3     
    
    
    
    
3     
    
    
    
    


I want to obtain an estimate of the linear model for each ID.
ex.   y = a1X1 + b1X2 + c1X3 + d1X4     where ID= 1
         y = a2X1 + b2X2 + c2X3 + d2X4    where ID= 2        and so on...

I'd like to obtain a table such this:

ID     a     b     c     d
1     ...     ...     ...     ..
2     ..     ..     ..     ..
3     ..     ..     ..     ..



Can you sugget me something?
Can I use a "for" script?
Thank you very much!
Valeria

    [[alternative HTML version deleted]]

______________________________________________
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.