R help - Sep 2004 - Retrieving objects from functions...

I've written a program that involves a loop that creates a matrix. I'd 
like to be able to manipulate that matrix on my R desktop, but after I 
run the function, that matrix does not appear when I type ls(). How can 
I make that matrix become an object that I can manipulate?

Thanks!

Hi,

On Thu, 30 Sep 2004, Jonathan Harris wrote:
> I've written a program that involves a loop that creates a matrix.
I'd
> like to be able to manipulate that matrix on my R desktop, but after I
> run the function, that matrix does not appear when I type ls(). How can
> I make that matrix become an object that I can manipulate?
If I understand you right, you want something like:
  foo <- function() {
     goo <- matrix(1:10, nrow = 5, ncol = 2)
  }
then be able to call goo after running foo()?  If this is what you want,
then you need to do something like:
  foo <- function() {
     goo <<- matrix(1:10, nrow = 5, ncol = 2)
  }
to force goo to become a global variable, instead of a local variable to
foo().

HTH,

Kevin

--------------------------------
Ko-Kang Kevin Wang
PhD Student
Centre for Mathematics and its Applications
Building 27, Room 1004
Mathematical Sciences Institute (MSI)
Australian National University
Canberra, ACT 0200
Australia

Homepage: http://wwwmaths.anu.edu.au/~wangk/
Ph (W): +61-2-6125-2431
Ph (H): +61-2-6125-7407
Ph (M): +61-40-451-8301

Jonathan Harris <jharris <at> hss.caltech.edu> writes:


: I've written a program that involves a loop that creates a matrix. I'd
: like to be able to manipulate that matrix on my R desktop, but after I 
: run the function, that matrix does not appear when I type ls(). How can 
: I make that matrix become an object that I can manipulate?

Just return the matrix as the value of your function.  If you are already
returning something else as the value of the function return a list with
that value and the matrix as the two components.

Check out the builtin eigen function is an example of this as it returns 
both eigenvalues and eigenvectors.  

The aforementioned is probably the best strategy but if you must then
you could alternately assign the matrix into the parent or global environment
from within your function using assign:

assign("mat", mat, parent.frame())  
assign("mat", mat, .GlobalEnv)

Jonathan Harris wrote:
> I've written a program that involves a loop that creates a matrix.
I'd
> like to be able to manipulate that matrix on my R desktop, but after I 
> run the function, that matrix does not appear when I type ls(). How can 
> I make that matrix become an object that I can manipulate?
Return it from the function and assign it outside:

foo <- function(anything){
   TheMatrix <- fun(anything)
   return(TheMatrix)
}

result <- foo(something)

Now, you have the resulting matrix assigned to an object called
"result".


Please read "An Introduction to R"!

Uwe Ligges

> Thanks!
> 
> ______________________________________________
> R-help at 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