Multiple left hand side variables in a formula

Gabor Grothendieck wrote

On Fri, Mar 1, 2013 at 7:16 PM, Frank Harrell <

f.harrell@

> wrote:

The lattice package uses special logic to allow for multiple
left-hand-side
variables in a formula, e.g. y1 + y2 ~ x.  Is there an elegant way to
do
this outside of lattice?  I'm trying to implement a data summarization
function that logically takes multiple dependent variables.  The usual
invocation of model.frame( ) causes R to try to do arithmetic addition
to
create a single dependent variable.

Try:

lm( cbind(Sepal.Length, Sepal.Width) ~., iris)

On Fri, Mar 1, 2013 at 8:02 PM, Frank Harrell <

f.harrell@

> wrote:

Thanks for your reply Gabor.  That doesn't handle a mixture of factor and
numeric variables on the left hand side.
Frank

It can handle 2 level factors

   lm(cbind(Sepal.Length, setosa = Species == "setosa") ~ ., iris)

and more with some manual effort:

   lm(cbind(virginica = Species == "virginica", setosa = Species ==
"setosa") ~ ., iris)

Typically you don't see more than that as a dependent variable.  Do
you actually need more?

--
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
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email: ggrothendieck at gmail.com

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