> -----Original Message-----
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of Stropharia
> Sent: Monday, October 12, 2009 4:07 PM
> To: r-help@r-project.org
> Subject: [R] Re use objects from within a custom made function
>
>
> Hi everyone,
>
> i'm having a problem extracting objects out of functions i've
> created, so i
> can use them for further analysis. Here's a small example:
>
> # ---------------------------
> test <- function(i, j){
> x <- i:j
> y <- i*j
> z <- i/j
> return(x,y,z)
> }
> # ---------------------------
>
> This returns the 3 objects as $x, $y and $z. I cannot,
> however, access these
> objects individually by typing for example:
>
> test$x
>
> I know i can do this by adding an extra arrow head to the
> assignment arrow
> (<<-), but I am sure that is not how it is done in some of
> the established R
> functions (like when calling lm$coef out of the lm function).
> Is there a
> simple command i've omitted from the function that allows
> access to objects
> inside it?
>
> Thanks in advance,
>
> Steve
> --
Steve,
I see a couple of problems (at least from my perspective). If you ever got
your function to run, you would see a warning stating that returning
multiple objects is deprecated. In your example of using the function, you
don't call it with any parameters, and the definition has no default values.
I also would be inclined to assign the results of the function call to a
variable/object and access the values from there.
So I would approach your problem as follows:
test <- function(i, j){
x <- i:j
y <- i*j
z <- i/j
list(x=x, y=y, z=z)
}
my.result <- test(1,4)
> my.result$x
[1] 1 2 3 4
>
If you don't want to assign the output of test() to an object, then you will
need to do something like
test(1,4)$x
But this is inefficient because each time you access one of the components,
you need to rerun the function.
Hope this is helpful,
Dan
Daniel Nordlund
Bothell, WA USA
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