R help - Mar 2008 - How to assign multiple return values

Hi,

I am moving from MATLAB, where one can easily assign a number of
output values from a function like this:

[x,y] = myfun(a,b)

Then variables x and y can be directly used in the caller workspace.

I understand that R functions return a single argument, which could be
a list. This in a way makes it possible to return multiple values with
a single function call, but accessing the list variables is a little
bit awkward.

mylist <-myfun(a,b) {
                      return(list(x = a, y = b))
                     }

x = mylist$x; y = mylist$y

I found some discussion going back to 2004. Is there anything new to
add to what was said at the time?

http://thread.gmane.org/gmane.comp.lang.r.general/21223/focus=21226
http://thread.gmane.org/gmane.comp.lang.r.general/42875/focus=42876

While at it, somewhere in the "Introduction to R", I think, I read
that use of "return" is considered a bad practice. Why is that? I
thought making clear what is returned by the function is a positive
thing...

Regards,

TL

On 24/03/2008 5:09 AM, Tribo Laboy wrote:
> Hi,
> 
> I am moving from MATLAB, where one can easily assign a number of
> output values from a function like this:
> 
> [x,y] = myfun(a,b)
> 
> Then variables x and y can be directly used in the caller workspace.
> 
> I understand that R functions return a single argument, which could be
> a list. This in a way makes it possible to return multiple values with
> a single function call, but accessing the list variables is a little
> bit awkward.
> 
> mylist <-myfun(a,b) {
>                       return(list(x = a, y = b))
>                      }
> 
> x = mylist$x; y = mylist$y
> 
> I found some discussion going back to 2004. Is there anything new to
> add to what was said at the time?
> 
> http://thread.gmane.org/gmane.comp.lang.r.general/21223/focus=21226
> http://thread.gmane.org/gmane.comp.lang.r.general/42875/focus=42876
I don't think so.
> While at it, somewhere in the "Introduction to R", I think, I
read
> that use of "return" is considered a bad practice. Why is that? I
> thought making clear what is returned by the function is a positive
> thing...
Where did you see that? It would be good advice if it said not to hide 
many calls to return() deep within a long function.  I'd be neutral 
about it if it said not to bother with return() in a very short 
function.  In intermediate cases, I think using return() is good practice.

Duncan Murdoch