On 02/21/2012 08:13 AM, Steve Lianoglou wrote:
Hi all,
This feature was throwing me for a loop for quite some time until I
played with the names of the slots.
Consider exhibit A:
==============
setClass("SVM",
representation=representation(
x='numeric',
y='numeric',
C='numeric',
eps='numeric'),
prototype=prototype(
x=numeric(),
y=numeric(),
C=numeric(),
eps=numeric()))
SVM<- function(x, y, C, eps) {
new("SVM", x=x, y=y, C=C, eps=eps)
}
And now a call to my "constructor"
R> SVM(1:10, 1:10, 1, 0.5)
Error in .getClassFromCache(Class, where) :
Class should be either a character-string name or a class definition
Hi Steve --
args(new) shows that new has a single named argument Class. R's rules of
partial matching mean that C matches Class before the unnamed "SVM", as in
f = function(XXX=1, ...) XXX
f(2, X=3) # returns 3
so name your arg to new
SVM <- function(x, y, C, eps) {
new(Class="SVM", x=x, y=y, C=C, eps=eps)
}
Martin
==================
This error occurs with both R-2.14.1 and R-devel
Changing the name name from `C` to `Cost` fixes it:
==================
setClass("svm",
representation=representation(
x='numeric',
y='numeric',
Cost='numeric',
eps='numeric'),
prototype=prototype(
x=numeric(),
y=numeric(),
Cost=numeric(),
eps=numeric()))
svm<- function(x, y, Cost, eps) {
new("svm", x=x, y=y, Cost=Cost, eps=eps)
}
R> svm(1:10, 1:10, 1, 0.5)
An object of class "svm"
Slot "x":
[1] 1 2 3 4 5 6 7 8 9 10
Slot "y":
[1] 1 2 3 4 5 6 7 8 9 10
Slot "Cost":
[1] 1
Slot "eps":
[1] 0.
===================
I was fishing around the R-devel mailing list w/ that error message to
see if anything turned up but I wasn't having any luck so it took a
while to figure out what was going on.
Is this known/intended behavior? Maybe I missed it in the
documentation (not sure where that might have been)?
If it is intended, maybe a better error message would be more useful?
Thanks,
-steve
--
Computational Biology
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N. PO Box 19024 Seattle, WA 98109
Location: M1-B861
Telephone: 206 667-2793
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