[I believe few users manipulate formulae and model frames like this, so
I'm posting here instead of R-help.]
I just found out that model.frame() includes all terms, including those
preceded by "-" in the formula, in its output (as mentioned on its help
page). Is there a recommended way of excluding "negative" terms? My
guess is that I can use info in the terms attribute to figure this out,
but that doesn't seem very straightforward. Any pointer would be much
appreciated.
Best,
Andy
Andy Liaw, PhD
Biometrics Research PO Box 2000 RY33-300
Merck Research Labs Rahway, NJ 07065
andy_liaw(a)merck.com 732-594-0820
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how to exclude terms preceded by - from model frame
2 messages · Liaw, Andy, Brian Ripley
On Wed, 19 Mar 2008, Liaw, Andy wrote:
[I believe few users manipulate formulae and model frames like this, so I'm posting here instead of R-help.] I just found out that model.frame() includes all terms, including those preceded by "-" in the formula, in its output (as mentioned on its help page). Is there a recommended way of excluding "negative" terms? My guess is that I can use info in the terms attribute to figure this out, but that doesn't seem very straightforward. Any pointer would be much appreciated.
?terms.formula, argument 'simplify', if I understand you aright.
Best, Andy Andy Liaw, PhD Biometrics Research PO Box 2000 RY33-300 Merck Research Labs Rahway, NJ 07065 andy_liaw(a)merck.com 732-594-0820
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595