Re: [R] Matrix of dummy variables from a factor

From: roger koenker <rkoenker_at_uiuc.edu>
Date: Wed 07 Dec 2005 - 10:31:19 EST

On Dec 6, 2005, at 3:27 PM, Berton Gunter wrote:

> But note: There are (almost?) no situations in R where the dummy
> variables
> coding is needed. The coding is (almost?) always handled properly
> by the
> modeling functions themselves.
>
> Question: Can someone provide a "straightforward" example where the
> dummy
> variable coding **is** explicitly needed?
>

Bert's question offers an opportunity for me to mention (again) my long standing wish
for someone to write a version of model.matrix that directly produced a matrix
in one of the common sparse matrix formats. This could be a good project for one of
you who like using ";" ?

Roger

url:    www.econ.uiuc.edu/~roger            Roger Koenker
email    rkoenker@uiuc.edu            Department of Economics
vox:     217-333-4558                University of Illinois
fax:       217-244-6678                Champaign, IL 61820

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