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[Rcpp-devel] Call by reference

Dirk Eddelbuettel
On 29 July 2015 at 13:05, Nathan Kurz wrote:
| I tried memory profiling both of your versions with a long vector, and
| found that the recommended Rcpp approach made an additional 8GB copy.
| Is there a way to avoid this extra copy without resorting to in place
| modification?

Look at Rcpp::XPtr for the most fine-grained control.  We have used that to
pass bigmemory object handles around.

| nate at ubuntu:~/R/byreference$ less abs.R
|   library(Rcpp)
| 
|   cppFunction("NumericVector absCopy(NumericVector & x) { return abs(x); }")

Copy-on-write semantics. *If* you alter you create copies.


All this is becoming a wee bit obscure.  The focus of the list is to help
people use R, not to navigate constraints built into the R system.

Dirk

Thread (13 messages)

Rguy Call by reference Jul 28 Dirk Eddelbuettel Call by reference Jul 28 Søren Højsgaard Call by reference Jul 28 Rguy Call by reference Jul 28 Dirk Eddelbuettel Call by reference Jul 29 Rguy Call by reference Jul 29 Dirk Eddelbuettel Call by reference Jul 29 Hao Ye Call by reference Jul 29 Nathan Kurz Call by reference Jul 29 Dirk Eddelbuettel Call by reference Jul 29 Dirk Eddelbuettel Call by reference Jul 29 Nathan Kurz Call by reference Jul 29 Dirk Eddelbuettel Call by reference Jul 29