[R] Function output

[David Winsemius]

  I think these examples will show what one can and cannot do with the  
invisible function.

 > f2 <- function(x,y) return(c(x, invisible(x^y))  )
 > f2(2,2)
[1] 2 4   #so that not the right way to keep tree hidden
 > f2 <- function(x,y) invisible(c(print(x),(x^y)) )
 > f2(2,2)
[1] 2   # success  x^y is calculate but not made visible on return
 > print(f2(2,2))
[1] 2          # that came from within the f2 function
[1] 2 4        # that is what the value returned by f2

On Sep 20, 2009, at 11:21 AM, David Winsemius wrote:

>
> On Sep 20, 2009, at 10:59 AM, manta wrote:
>
>>
>> Good afternoon,
>> I know it is a simple question but I cannot figure out how to solve  
>> this
>> issue.
>> I have a function that calculate two objects. I would like to choose
>> everytime about the tree object, with default to not show it.
>
> I cannot understand that. Perhaps you can try again to tell us what  
> you want to do with tree?
>
>>
>> OP<-function(S=100,X,sigma,mu=0,r=0,time=1,n)
>> {
>> 	value=(S)	
>> 	......			
>>   	tree = matrix(rev(tree), byrow = FALSE, ncol = n + 1)	
>
> ... where did tree first get defined?
>
>> 	return(value[1])
>
> ... do you really want to return only value[1] _and_not_ tree? If  
> you exit the function this way, tree will get lost.
>
>
>> }
>>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT