[R] modifying arrays within functions

[Martin Elff]

On Tuesday 05 February 2008 (16:51:41), Konrad BLOCHER wrote:
> Hi,
>
> I'm pretty new to R and seem to be having difficulties with writing a
> function that would change an array and keep the change after the function
> finishes its work.
>
It seems you want this:

X<-array(1,dim=c(2,2))
addition<-function(a){
	X[1,1] <<- X[1,1]+a # not '='
}
addition(1)
X


     [,1] [,2]
[1,]    2    1
[2,]    1    1
                           

Nevertheless I would advise against writing and using functions that
have side effects outside their scope. 
It is in general dangerous.

Best, 

Martin