On Tue, 29 Dec 2009, Phil Spector wrote:
Nancy -
Please notice that ** is not an R operator. The caret (^) is the
exponentiation operator in R.
- Phil
Actually, no,
2**3
[1] 8
Indeed ^ is the preferred exponentiation operator, but ** has 'always'
been allowed. See the following note in ?"^"
Note:
‘**’ is translated in the parser to ‘^’, but this was undocumented
for many years. It appears as an index entry in Becker _et al_
(1988), pointing to the help for ‘Deprecated’ but is not actually
mentioned on that page. Even though it has been deprecated in S
for 20 years, it is still accepted.
I added that note in May 2008 (and it is not intended to be a
reference to current versions of S-PLUS, since we cannot keep checking
that, but that Svr4 accepted it).
On Tue, 29 Dec 2009, Nancy Adam wrote:
Hi everyone,
I tried to write the code of computing R2 for a regression system but I
failed.
This is the code I use for computing RMSE:
my_svm_model <- function(myformula, mydata, mytestdata)
{
mymodel <- svm(myformula, data=mydata)
mytest <- predict(mymodel, mytestdata)
error <- mytest - mytestdata[,1]
-sqrt(mean(error**2))
}
can anyone please tell me what I have to change to compute R2 instead of
RMSE?
Many thanks,
Nancy
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--
Brian D. Ripley, rip...@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)
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