[R] predict()
Terry Therneau
therneau at mayo.edu
Thu Apr 14 14:59:50 CEST 2011
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I am experimenting with the function predict() in two versions of R and
the R extension package "survival".
library(survival)
set.seed(123)
testdat=data.frame(otime=rexp(10),event=rep(0:1,each=5),x=rnorm(10))
testfm=as.formula('Surv(otime,event)~x')
testfun=function(dat,fm)
{
predict(coxph(fm,data=dat),type='lp',newdata=dat)
}
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The question was: this works under survival 2.35-8, but not survival
2.36-5
Answer: The predict and underlying model.frame functions for coxph were
brought into line with lm and other models. The major advantage is that
I now deal with factors and data dependent predictors like ns()
correctly.
You've shown a disadvantage of which I was not aware. Using your
example but replacing coxph() by lm() with otime ~x as the model I get a
similar failure. I'd like to ask a wider audience of R-devel since it
is bigger than coxph.
Terry Therneau
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