[R] lda() called with data=subset() command

[Christoph Lehmann]

Hi
I have a data.frame with a grouping variable having the levels 

C, 
mild AD, 
mod AD, 
O and 
S

since I want to compute a lda only for the two groups 'C' and 'mod AD' I
call lda with data=subset(mydata.pca,GROUP == 'mod AD' | GROUP == 'C')


my.lda <- lda(GROUP ~ Comp.1 + Comp.2 + Comp.3 + Comp.4+  Comp.5 +
Comp.6 + Comp.7 + Comp.8  , data=subset(mydata.pca,GROUP == 'mod AD' |
GROUP == 'C'), CV = TRUE)

this results in the warning "group(s) mild AD O S are empty in:
lda.default(x, grouping, ...)" of course...

my.lda$class now shows 

 [1] C       C       C       C       C       C       C       C       C
[10] C       C       C       C       C       C       C       C       C
[19] C       C       C       mild AD mild AD mild AD mild AD mild AD
mild AD
[28] mild AD C       mild AD mild AD mild AD C       C       mild AD
mild AD
[37] mild AD mild AD
Levels: C mild AD mod AD O S

it seems it just took the second level (mild AD) for the second class,
even though the second level was not used for the lda computation (only
the first level (C) and the third level (mod AD)

what shall I do to resolve this (little) problem?

thanks for a  hint

christoph
-- 
Christoph Lehmann <christoph.lehmann at gmx.ch>