[Rcpp-devel] multidimensional arrays

[Steve Lianoglou]

Hi Frederico,

On Fri, Jun 15, 2012 at 5:27 AM, Frederico Mestre
<mestre.frederico at gmail.com> wrote:
> Hello all:
>
> I’m a regular user of R, but my knowledge of C++ is limited.
>
> I need to create functions to generate random landscapes (with two habitat
> classes) based on area and distance amongst patches. This would take quite a
> long time in R so I thought it would be better to use Rcpp (which seems a
> simpler way to integrate R and C++). I need to generate these landscapes for
> the current time and their evolution in the future (about 1000 to each of
> these time steps).
> I thought it would be better to generate these “landscapes” as
> multidimensional arrays but I’m finding it hard to work with C++.
>
> Would it be adequate to use this functions:
>
> rdlandscape <- cxxfunction(signature(x = "numeric"), body = "C++ code",
> plugin="Rcpp")
>
> I don’t need to retain these objects after the run just calculate several
> parameters (as extinction probability) of a species that would be present in
> these landscapes.
>
> Any ideas?

It's hard to provide any ideas -- you're giving us very little to work with.

We're not sure (at least I'm not) what exactly you're trying to do, so
I'll take it as truth that generating these in R will result in
prohibitively long running time, in this case looking to Rcpp is a
great idea -- yes, it makes integrating C++ w/ R much easier.

But what type of ideas are you looking to get here -- assuming you
substitute the correct C++ code in your `body="C++ code", then you'll
be a happy camper ... the trick is getting the right code in there.

Also, once you do get the right code, you probably want to turn this
stuff into a package so you don't have to inline/compile it every time
you start a new R session.

People can provide more help when you start implementing these thing
and run into a particular wall with Rcpp itself. At that point, please
provide a better description of what you're trying to do, what you've
actually tried, and where the exact problem is. Until then, there
isn't much else we can do for you now.

-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