jim holtman wrote: > ?missing > > On 7/2/06, Jonathan Greenberg <[EMAIL PROTECTED]> wrote: >> I'm a bit new to writing R functions and I was wondering what the "best >> practice" for having optional variables in a function is, and how to test >> for optional and non-optional variables? e.g. if I have the following >> function: >> >> helpme <- function(a,b,c) { >> >> >> } >> >> In this example, I want c to be an optional variable, but a and b to be >> required. How do I: >> 1) test to see if the user has inputted c >> 2) break out of the function of the user has NOT inputted a or b.
if(missing(c)) stop("need c") or if(missing(c)) return() depending on your problem it might be better to provide sensible default values for a,b,c in the function definition helpme<-function(a=A, b=B, c=C) {...} instead of enforcing that every argument is specified? joerg >> >> Thanks! >> >> --j >> >> -- >> >> Jonathan A. Greenberg, PhD >> NRC Research Associate >> NASA Ames Research Center >> MS 242-4 >> Moffett Field, CA 94035-1000 >> Phone: 415-794-5043 >> AIM: jgrn3007 >> MSN: [EMAIL PROTECTED] >> >> ______________________________________________ >> R-help@stat.math.ethz.ch mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide! >> http://www.R-project.org/posting-guide.html >> > > > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html