[R] R equiv of #ifdef?
Peter Dalgaard BSA
p.dalgaard at biostat.ku.dk
Mon Jun 7 11:38:29 CEST 1999
Bill Simpson <wsimpson at gcal.ac.uk> writes:
> I was wondering if R has an equivalent of #ifdef.
> I want the code to check if a function has been sourced in yet, and if
> not, then source it in. (I know of replace(), which works for
> Here is what I have come up with.
> junk.r contains the code for function thingy2().
> This doesn't work: "missing value where logical needed"
> The error message puzzles me.
How about exists("thingy2")?
The error message is perhaps not perfectly clear, you need not only a
logical but a non-missing logical of positive length:
Error in if (logical(0)) 2 : missing value where logical needed
Error in if (NULL) 2 : missing value where logical needed
Error in if (as.logical(NA)) 2 : missing value where logical needed
You're getting a zero-length vector from the
my.objects[my.objects=="thingy2"] construction, which is compared
elementwise with "thingy2".
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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