Re: [Rd] pass-by-reference

From: Henrik Bengtsson <hb_at_stat.berkeley.edu>
Date: Thu, 08 Jul 2010 09:20:11 +0200

...and for tracing memory allocations/duplications, see tracemem().

/Henrik

On Thu, Jul 8, 2010 at 9:14 AM, Henrik Bengtsson <hb_at_stat.berkeley.edu> wrote:
> See packages R.oo and proto.
>
> If you wish to do it yourself, you want to utilize environments for this.
>
> /Henrik
>
> On Thu, Jul 8, 2010 at 6:52 AM, Paul Bailey <pdbailey_at_umd.edu> wrote:
>>
>> I'm working with a large object that I want to modify slightly in a function.
>> Pass-by-reference would make a lot of sense, but I don't know how to do it.
>>
>> I've searched this archive and thought that I can do something like
>>
>> f <- function(x) {
>>  v1 <- list(a=x,b=3)
>>  g(x)
>>  v1
>> }
>> g <- function(x) {
>>  frame <- parent.frame()
>>  assign("v1",list(a=x,b=x),frame)
>> }
>> f(4)
>> returns list(a=4,b=4)
>>
>> but what if I wanted to make v1[[1]] = v1[[1]] + v1[[2]] without creating a
>> copy of v1?
>>
>> f2 <- function(x) {
>>  v1 <- list(a=x,b=3)
>>  g2(x)
>>  v1
>> }
>> g2 <- function(x) {
>>  frame <- parent.frame()
>>  v1 <- get("v1",envir=frame)
>>  v1[[1]] <- v1[[1]] + v1[[2]]
>> }

>> f2(4)
>>
>> but this fails. (it returns list(a=4,b=3) because v1 was copied into g2, not
>> passed by reference) Is there a way to do this?
>> --
>> View this message in context:
http://r.789695.n4.nabble.com/pass-by-reference-tp2281802p2281802.html
>> Sent from the R devel mailing list archive at Nabble.com.
>>
>> ______________________________________________
>> R-devel_at_r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>



R-devel_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel Received on Thu 08 Jul 2010 - 07:22:30 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Thu 08 Jul 2010 - 13:20:13 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-devel. Please read the posting guide before posting to the list.

list of date sections of archive