Re: [R] calling objects in a foreloop

[Thomas Lumley]

On Mon, 14 Mar 2005, Benjamin M. Osborne wrote:
I want to organize outputs from several regressions into a handy table.  When I
try the following, each of my "fit_s" is replaces instead of read.  Is there a
way to read from the regression summaries that does not require writing
separate lines of code for each?

Put the lm objects into a list rather than into separate variables, then 
you can loop or lapply() over the list.

fits<-vector("list",8)
fits[[1]]<-lm(dBA.spp16$sp2.dBA.ha~dBA.spp16$sp1.dBA.ha)
fits[[2]]<-lm(dBA.spp16$sp3.dBA.ha~dBA.spp16$sp1.dBA.ha)
etc
dBA.spp16.fits<-matrix(NA, nrow=8, ncol=5)
for (i in 1:8){
    summ<-summary(fit[[i]])
    dBA.spp16.fits[i,2]<-summ$coef[1,1]
    dBA.spp16.fits[i,3]<-summ$coef[2,1]
    dBA.spp16.fits[i,4]<-summ$r.squared
    dBA.spp16.fits[i,5]<-summ$adj.r.squared
}
Other things to note
1/  You can't put the formula into a numeric matrix
2/ lm(dBA.spp16$sp2.dBA.ha~dBA.spp16$sp1.dBA.ha) can be more elegantly 
written as
   lm(sp2.dBA.ha~sp1.DB.ha, data=dBA.spp16)

When you find yourself doing computations on the names of objects rather 
than on their values it is usually a bad sign.

    -thomas
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