R help - Dec 2004 - nls question

Just a quick question.  Is there a way to easily specify factor levels in a
function definition within nls?  For example, I am trying to fit a 3 parameter,
nonlinear Weibull function to tree height and I would like to have results by
species (or down the road a bit, by plot).  I am hoping there is someway to do
it easily, similar to the "gas example" in the ANCOVA chapter in
Modern Applied Statistics with S, and not running it with a "by"
function or making a very complex function statement with all factor levels
combinations.

Can someone point me in the right direction?

Thanks,
Mike

Mike Saunders
Research Assistant
Forest Ecosystem Research Program
Department of Forest Ecosystem Sciences
University of Maine
Orono, ME  04469
207-581-2763 (O)
207-581-4257 (F)

	[[alternative HTML version deleted]]

Mike
nlsList from nlme library can fit nonlinear models for dataset grouped by
some specification, e.g. by specie in your case
Regards
Christian
>-- Mensaje Original --
>From: "Mike Saunders" <mike_saunders at umenfa.maine.edu>
>To: "R Help" <r-help at stat.math.ethz.ch>
>Date: Thu, 16 Dec 2004 10:40:00 -0500
>Subject: [R] nls question
>
>
>Just a quick question.  Is there a way to easily specify factor levels
in
>a function definition within nls?  For example, I am trying to fit a 3
parameter,
>nonlinear Weibull function to tree height and I would like to have results
>by species (or down the road a bit, by plot).  I am hoping there is someway
>to do it easily, similar to the "gas example" in the ANCOVA
chapter in
Modern
>Applied Statistics with S, and not running it with a "by" function
or making
>a very complex function statement with all factor levels combinations.
>
>Can someone point me in the right direction?
>
>Thanks,
>Mike
>
>Mike Saunders
>Research Assistant
>Forest Ecosystem Research Program
>Department of Forest Ecosystem Sciences
>University of Maine
>Orono, ME  04469
>207-581-2763 (O)
>207-581-4257 (F)
>
>	[[alternative HTML version deleted]]
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html