# R-alpha: two-sided to one-sided formula

**Peter Dalgaard BSA
**
p.dalgaard@biostat.ku.dk

*02 Dec 1997 19:21:47 +0100*

Douglas Bates <bates@stat.wisc.edu> writes:
>* In general it would not be a good idea to propagate the formula class
*>* to subsets but it does make sense in this case. We can get around it
*>* by replacing ttt[-2] by do.call("~", ttt[-(1:2)]) I suppose. Any
*>* opinions on whether ttt[-2] should still be a formula?
*
Hum. tt[-i] is a well-defined formula iff (i != 1). Somehow, I dislike
the idea of properties depending on the value of a parameter, so I'm
inclined to say no. BTW,
eval(as.call(ttt[-2]))
also works. And one would *think* that formula(as.call(ttt[-2])) did
too, but typeof(as.call(...))==language and !=call (is this weird or
not?), so formula.default protests.
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907
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