R help - Jul 2006 - Optional variables in function?

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.

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: jgrn3007 at hotmail.com

?missing

On 7/2/06, Jonathan Greenberg <jgreenberg@arc.nasa.gov>
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.
>
> 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: jgrn3007@hotmail.com
>
> ______________________________________________
> 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
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

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