[R] Manipulating code?

Gabor Grothendieck ggrothendieck at gmail.com
Tue May 23 19:54:32 CEST 2006

Its not entirely clear to me what you want to do but these will
do the indicated regression on the subset of the data for which
Species is "setosa" and then do it again but for the subset for
which Species is "virginica":

lm(Sepal.Length ~ Sepal.Width, iris, subset = Species == "setosa")
lm(Sepal.Length ~ Sepal.Width, iris, subset = Species == "virginica")

Does that answer your question?

On 5/23/06, Johannes Hüsing <johannes at huesing.name> wrote:
> Dear expeRts,
> I am currently struggling with the problem of finding
> cut points for a set of stimulus variables. I would like
> to obtain cut points iteratively for each variable by
> re-applying a dichotomised variable in the model and then
> recalculate it. I planned to have fixed names for the
> dichotomised variables so I could use the same syntax
> for every recalculation of the whole model. I furthermore
> want to reiterate the process until no cut point changes
> any more.
> My problem is in accomplishing this syntactically. How can
> I pass a variable name to a function without getting lost
> in "as.symbol" and "eval" and "parse" mayhem? I am feeling
> I am thinking too much in macro expansion à la SAS when
> trying to tackle this.
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