[R] Creating R packages, passing by reference and oo R.

[Gabor Grothendieck]

Passing by value does not necessarily mean physical copying.  Check out this:

> x <- matrix(1:1000^2, 1000, 1000)
> gc()
         used (Mb) gc trigger (Mb) max used (Mb)
Ncells 114520  3.1     350000  9.4   350000  9.4
Vcells 577124  4.5    1901092 14.6  1577448 12.1
> f <- function(x) { y <- max(x); print(gc()); y }
> f(x)
         used (Mb) gc trigger (Mb) max used (Mb)
Ncells 114560  3.1     350000  9.4   350000  9.4
Vcells 577133  4.5    1901092 14.6  1577448 12.1
[1] 1000000
> R.version.string
[1] "R version 2.10.1 (2009-12-14)"
> win.version()
[1] "Windows Vista (build 6002) Service Pack 2"


On Mon, Apr 5, 2010 at 7:35 AM, Roger Gill <roger.gill1979 at yahoo.co.uk> wrote:
> Dear All,
>
> I would like some advice on creating R packages, passing by reference and oo R.
>
> I have created a package that is neither elegant nor extensible and rather cumbersome (it works). I would like to re write the code to make the package distributable (should it be of interest) and easy to maintain.
>
> The package is for Bayesian model determination via a reversible jump algorithm and has currently been written to minimise computational expense.
>
> At every iteration of the MCMC I make a call to a likelihood function. Here, I pass by value a matrix containing the explanatory variables of the current model and this is quite costly if X is quite large. This matrix could change at every iteration (it's certainly proposed). Ideally I would pass by reference (a pointer in C, \@ in perl etc...) and allow the user to specify this function should they so desire. This is where I become a little stuck.
>
> I have searched the lists, used google and not found a accepted solution. How do I pass by ref? What are my options? Can you point me towards some suitable reading? Are there any good examples? How have others overcome this problem.
>
> Thanks in advance,
>
> best wishes
>
> Roger
>
>
>
>
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