I'm trying to make a formula and I got the error:
$ operator not defined for this S4 class with R.
First of all, what is a S4 class? What am I doing wrong?
Following the code:
as.formula("ctree(d$sex ~ d$ahe , data = d)")
If you want to reproduce it, the dataset (CSV file) d
is available here.
You are giving as.formula
the wrong input here. Only d$sex ~ d$ahe
should be a formula, so:
ctree(as.formula("d$sex ~ d$ahe"))
Or:
ctree(as.formula("sex ~ ahe"), data = d)