[R] as.formula and lme ( Fixed effects: Error in as.vector(x, "list") : cannot coerce to vector)

[Dieter Menne]

Using a formula converted with as.formula with lme leads
to an error message. Same works ok with lm, and with
lme and a fixed formula.

# demonstrates problems with lme and as.formula
demo<-data.frame(x=1:20,y=(1:20)+rnorm(20),subj=as.factor(rep(1:2,10)))
demo.lm1<-lme(y~x,data=demo,random=~1|subj)
print(summary(demo.lm1))
newframe<-data.frame(x=1:5,subj=rep(1,5))
predict(demo.lm1,newframe,level=0)

fma<-as.formula("y~x")
demo.lm<-lm(fma,data=demo)        # ok
predict(demo.lm,newframe,level=0) # ok
demo.lm2<-lme(fma,data=demo,random=~1|subj) # looks ok, but isn't
print(summary(demo.lm2))

#Fixed effects: Error in as.vector(x, "list") : cannot coerce to vector
#predict(demo.lm2,newframe,level=0) # does not work


---------------------------------------
Dr. Dieter Menne
Biomed Software
72074 Tübingen
Tel (49) (7071) 52176
FAX (49) (7071) 55 10 46
dieter.menne at menne-biomed.de
www.menne-biomed.de

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