R help - Feb 2010 - multi-argument returns

Dear R users,

I have multi-argument returns in a function and I am warned by the program
they are deprecated.

I have found this in the R-help archives :

http://tolstoy.newcastle.edu.au/R/help/01c/0319.html
http://tolstoy.newcastle.edu.au/R/help/01c/0356.html

Since I am not too good at programming, the list solution seems the better
one for me. It is also the one advocated by Kevin Murphy.

So rather than writing return(x,y,z), I should write at the end of my
function :

g=function() {

    #...

    result=list(x,y,z)
    return(result)
}

Is that correct ?

Then shoud l use g[1] or g[[1]] ?

Thank you for you help.

Randall

	[[alternative HTML version deleted]]

On Wed, 17 Feb 2010, Randall Wrong wrote:
> Dear R users,
>
> I have multi-argument returns in a function and I am warned by the program
> they are deprecated.
Defunct as from the next R release.
> I have found this in the R-help archives :
in 2001!
> http://tolstoy.newcastle.edu.au/R/help/01c/0319.html
> http://tolstoy.newcastle.edu.au/R/help/01c/0356.html
>
> Since I am not too good at programming, the list solution seems the better
> one for me. It is also the one advocated by Kevin Murphy.
>
> So rather than writing return(x,y,z), I should write at the end of my
> function :
return(list(x=x,y=y,z=z)) is the preferred replacement.
(As the help page for return() has long said.)
> g=function() {
>
>    #...
>
>    result=list(x,y,z)
>    return(result)
> }
>
> Is that correct ?
>
> Then shoud l use g[1] or g[[1]] ?
No change is needed (I think you mean g()$x etc) as return(x,y,z) and 
return(list(x=x,y=y,z=z)) are identical in their effects.
> Thank you for you help.
>
> Randall
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

Hi,

On Wed, Feb 17, 2010 at 4:09 PM, Randall Wrong <randall.wrong at
gmail.com> wrote:
> Dear R users,
>
> I have multi-argument returns in a function and I am warned by the program
> they are deprecated.
>
> I have found this in the R-help archives :
>
> http://tolstoy.newcastle.edu.au/R/help/01c/0319.html
> http://tolstoy.newcastle.edu.au/R/help/01c/0356.html
>
> Since I am not too good at programming, the list solution seems the better
> one for me. It is also the one advocated by Kevin Murphy.
>
> So rather than writing return(x,y,z), I should write at the end of my
> function :
>
> g=function() {
>
> ? ?#...
>
> ? ?result=list(x,y,z)
> ? ?return(result)
> }
>
> Is that correct ?
FYI, in R the last line of a function is its return value, so you
could simply do:

g <- function() {
  list(x=x, y=y, z=z)
}
> Then shoud l use g[1] or g[[1]] ?
Just to avoid a mistake or ambiguity here, I wouldn't use "g" as a
variable because you are using that as your function name.

So after defining the function `g`, you could do:

myvalue <- g()

Then you would use: myvalue[[1]]

myvalue[1] would return you a list that has one element in it (the
first one), where as using myvalue[[1]] just gives you the first
element of the list.

Using "named" arguments when constructing your list as I did (eg.
list(x=x, ...)), you can then also do:

myvalue$x

Hope that helps,
-steve
-- 
Steve Lianoglou
Graduate Student: Computational Systems Biology
 | Memorial Sloan-Kettering Cancer Center
 | Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact