Hi
Martin Maechler maech...@stat.math.ethz.ch napsal dne 15.12.2009
09:17:55:
PP == Petr PIKAL petr.pi...@precheza.cz
on Tue, 15 Dec 2009 09:03:11 +0100 writes:
PP Hi
PP r-help-boun...@r-project.org napsal dne 15.12.2009 00:25:10:
Hi All,
I need to run muliple lm functions. My independent variables are
called
dataset$x1, x2, x3, x4 etc.
How can I use a loop counter variable to replace the numbers?
fit1=lm(dataset$y~dataset$x1)
fit2=lm(dataset$y~dataset$x2)
fit3=lm(dataset$y~dataset$x3)
fit4=lm(dataset$y~dataset$x4)
PP I would use list for results and brackets for lm fit. Something
like
PP (untested)
PP fit- vector(list, length=4)
PP for (i in 1:4) {
PP fit[[i]] - lm(y~dataset[,i], data=dataset)
PP }
Also, in almost all such cases,
where you have many regressions, you'd rather want lm.fit()
instead of lm(), for efficiency reasons.
lm.fit() is probably among the much R functions that are less
known than they should be.
It *would* be known more if useRs *would* read help pages ...
?lm in this case.
Point taken. I do not use lm in cycles very often and when doing so I did
not encounter performance problem yet.
R computation is almost always quicker then me when I try to think about
the problem to be solved correctly.
And personally I prefer to put everything in nice pictures instead of
reading output from n fits. Therefore I try to make multipage PDF plots
which can have more than two dimensions by col, pch and size variation
with other variables. Than I can list through it to see if there is some
pattern.
Regards
Petr
Martin
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