[R] replacing characters in formulae / models
Charles C. Berry
cberry at tajo.ucsd.edu
Thu Nov 6 17:28:09 CET 2008
On Thu, 6 Nov 2008, Christoph Scherber wrote:
> Dear all,
> How can I replace text in objects that are of class "formula"?
> y="a * x + b"
What exactly are you trying to accomplish??
And why did you assign 'formula' as the class of a character string?
'y' is not a valid formula object:
Error in terms.formula(formula, data = data) :
argument is not a valid model
Perhaps, you need to review
11 Statistical models in R
from Introduction to R.
Oh, yes. There is the matter of reviewing the _posting guide_ before
> Suppose I would like to replace the "x" by "w" in the formula object "y".
> How can this be done? Somehow, the methods that can be used in character
> objects do not work 1:1 in formula objects...
> Many thanks and best wishes
> Dr. rer.nat. Christoph Scherber
> University of Goettingen
> DNPW, Agroecology
> Waldweg 26
> D-37073 Goettingen
> phone +49 (0)551 39 8807
> fax +49 (0)551 39 8806
> Homepage http://www.gwdg.de/~cscherb1
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
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