[R] Multiple left hand side variables in a formula

[Frank Harrell]

Hi Gabor,

This is not for a regression function but for a major update I'm working on
for the summary.formula function in the Hmisc package.  So I need to handle
several data types in the formula.

Thanks
Frank

Gabor Grothendieck wrote
>> 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.
> tel: 1-877-GKX-GROUP
> email: ggrothendieck at gmail.com
> 
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-----
Frank Harrell
Department of Biostatistics, Vanderbilt University
--
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