[R] Extracting original variable list from lm object

[Sung, Iyue]

perfect. many thanks. 

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Sent: Tuesday, February 19, 2008 1:26 PM
To: Sung, Iyue
Cc: r-help at r-project.org
Subject: Re: [R] Extracting original variable list from lm object

Try:

all.vars(formula(my.model))


On Feb 19, 2008 1:10 PM, Sung, Iyue <Iyue.Sung at lippincott.com> wrote:
> Fellow R users,
>
> I have an lm object, from which I would like to extract the list of 
> original variables.
> The problem I have is the formula includes functions of the
covariates.
>
> I tried using "attr", but the result stores the transformed variable 
> name.  For example:
>
> > my.model<-lm(y ~ a + log(b + 1), data=my.data) 
> > as.character(attr(my.model$terms, "variables"))[-1]
>  [1] "y" "a" "log(b + 1)"
>
> But I just want a character vector of the original variables ("y", 
> "a", "b"), not ("y", "a", "log(b + 1)").
> Does someone have a solution they could kindly share?
>
> Thanks,
> Iyue
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