Message-ID: <2E758EB9-8FA8-43D6-BE84-3033A5816E2A@uiuc.edu>
Date: 2005-12-06T23:31:19Z
From: Roger Koenker
Subject: Matrix of dummy variables from a factor
In-Reply-To: <200512062127.jB6LREMM000562@volta.gene.com>
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 at uiuc.edu Department of Economics
vox: 217-333-4558 University of Illinois
fax: 217-244-6678 Champaign, IL 61820