R help - Nov 2005 - How can I assign an argument to transfer whether by ref or by value?

Hello guys,

I am wondering the default way of transferring arguments in R. Is it by
value or by ref in default case, or could that be changed explicitly?

Cheers,
Xiaofan

---
Xiaofan Li
Department of Applied Mathematics and Theoretical Physics
University of Cambridge

Xiaofan Li wrote:
> Hello guys,
> 
> I am wondering the default way of transferring arguments in R. Is it by
> value or by ref in default case, or could that be changed explicitly?
R passes by value.  It's worth reading the language definition manual to 
find out about the subtleties (e.g. lazy evaluation).

Duncan Murdohc
> 
> Cheers,
> Xiaofan
> 
> ---
> Xiaofan Li
> Department of Applied Mathematics and Theoretical Physics
> University of Cambridge
> 
> ______________________________________________
> 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

I do not understand what your question is. Can you clarify with an
example or analogies to other programming language.

 my.fun <- function(x, y=1){ x^y }

 my.fun(5)        # returns 5 
 my.fun(5, 2)     # returns 25
 my.fun(y=2, x=5) # returns 25

Regards, Adai


On Sun, 2005-11-06 at 03:28 +0000, Xiaofan Li wrote:
> Hello guys,
> 
> I am wondering the default way of transferring arguments in R. Is it by
> value or by ref in default case, or could that be changed explicitly?
> 
> Cheers,
> Xiaofan
> 
> ---
> Xiaofan Li
> Department of Applied Mathematics and Theoretical Physics
> University of Cambridge
> 
> ______________________________________________
> 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
> 
-- 
Adaikalavan Ramasamy                    ramasamy at cancer.org.uk
Centre for Statistics in Medicine       http://www.ihs.ox.ac.uk/csm/
Wolfson College Annexe                  Tel : 01865 284 408
Linton Road, Oxford OX2 6UD             Fax : 01865 284 424

i think this question was already answered but just to elaborate,
pass by value means that a copy of the argument is passed to the
function so if the argument is changed in the function its not changed
in the caller.  Pass by reference means its changed in the caller too.
R passes by value although there are workarounds to pass by
reference.  In the following f uses pass by value and g pass by
reference.
> y <- 1
> f <- function(x) x<-x+1
> f(y)
> y
[1] 1
> g <- function(x) eval.parent(substitute(x <- x+1))
> g(y)
> y
[1] 2


On 11/6/05, Adaikalavan Ramasamy <ramasamy at cancer.org.uk>
wrote:
> I do not understand what your question is. Can you clarify with an
> example or analogies to other programming language.
>
>  my.fun <- function(x, y=1){ x^y }
>
>  my.fun(5)        # returns 5
>  my.fun(5, 2)     # returns 25
>  my.fun(y=2, x=5) # returns 25
>
> Regards, Adai
>
>
> On Sun, 2005-11-06 at 03:28 +0000, Xiaofan Li wrote:
> > Hello guys,
> >
> > I am wondering the default way of transferring arguments in R. Is it
by
> > value or by ref in default case, or could that be changed explicitly?
> >
> > Cheers,
> > Xiaofan
> >
> > ---
> > Xiaofan Li
> > Department of Applied Mathematics and Theoretical Physics
> > University of Cambridge
> >
> > ______________________________________________
> > 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
> >
> --
> Adaikalavan Ramasamy                    ramasamy at cancer.org.uk
> Centre for Statistics in Medicine       http://www.ihs.ox.ac.uk/csm/
> Wolfson College Annexe                  Tel : 01865 284 408
> Linton Road, Oxford OX2 6UD             Fax : 01865 284 424
>
> ______________________________________________
> 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
>