[R] "main" parameter in plot.default vs plot.formula
Berton Gunter
gunter.berton at gene.com
Thu Feb 9 19:00:07 CET 2006
Folks:
R 2.2.0 on Windows.
I find the following somewhat puzzling:
> a<-1; x<-0:1; y<-x
## following works fine:
> plot(x,y ,main= bquote(n[1] == .(a) ))
## following produces an error:
> plot(y~x ,main= bquote(n[1] == .(a) ))
Error in paste(n[1] == 1, " and ", n[2] == 2) : object "n" not found
*******************************
Note 1: I assume that this is due to the following documented behavior of
plot.formula():
"Both the terms in the formula and the ... arguments are evaluated in data
enclosed in parent.frame() if data is a list or a data frame."
Nevertheless, the behavior seems inconsistent to me. Am I missing something
(including the "I assume ..." comment)?
Note 2: If one uses substitute() instead, it works fine:
plot(y~x ,main= substitute(bquote(n[1] == a),list(a=a)))
Any illumination, public or private, would be appreciated.
Cheers,
Bert
-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
"The business of the statistician is to catalyze the scientific learning
process." - George E. P. Box
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