Re: [R] Optional variables in function?

2006-07-03 Thread Joerg van den Hoff 
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]

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Re: [R] Optional variables in function?

2006-07-02 Thread jim holtman 
?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.

 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




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

What is the problem you are trying to solve?

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[R] Optional variables in function?

2006-07-01 Thread Jonathan Greenberg 
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: [EMAIL PROTECTED]

__
R-help@stat.math.ethz.ch mailing list
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