[Rcpp-devel] Fwd: List of uniform_int_distribution objects

[aakremena at aol.com]

 Hi all,

I have decided to follow Dirk's advice and use more classical STL containers rather than Rcpp::List one.

It works for me but I admit that I am still in the dark as to why the Rcpp::List way doesn't work.

Thus, I consider this topic closed.

Thanks.

Anguel

 

 

-----Original Message-----
From: Dirk Eddelbuettel <edd at debian.org>
To: aakremena <aakremena at aol.com>
Cc: rcpp-devel <rcpp-devel at lists.r-forge.r-project.org>
Sent: Tue, Apr 26, 2016 1:52 pm
Subject: Re: [Rcpp-devel] List of uniform_int_distribution objects


On 26 April 2016 at 14:45, aakremena at aol.com wrote:
| Hi everybody,
| 
|    1. I am trying to create an Rcpp list, each of whose elements contain an
| uniform_int_distribution object.
| 
|    2. My understanding is that since an uniform_int_distribution object is a
| non-SEXP one, I need to create a specialization of wrap() first.
| 
|    3. To this end, I am using the following (sample) piece of code:
| 
| #include <RcppCommon.h>
| #include <random>
| namespace Rcpp {
|   template <> SEXP wrap(const std::uniform_int_distribution<int> &d);
| }
| #include <Rcpp.h>
| using namespace Rcpp;
| 
| // [[Rcpp::export]]
| Rcpp::List List_of_Distributions() {
|   Rcpp::List DISTR(2);
|   std::uniform_int_distribution<int> dist_1(0, 5); 
| std::uniform_int_distribution<int> dist_2(0, 6);
|   DISTR[0] = Rcpp::wrap(dist_1);  DISTR[1] = Rcpp::wrap(dist_2);
| 
|   return DISTR;
| }
| 
| /*** R
| List_of_Distributions()
| */
| 
|    4. The compilation fails with a message
| 
| Error in dyn.load("/var/folders/12/bqytpkx93w97r3s3_h9q9k_00000gn/T//Rtmpm2tVkx
| /sourcecpp_f9e75ec42b87/sourceCpp_220.so") :
|   unable to load shared object '/var/folders/12/bqytpkx93w97r3s3_h9q9k_00000gn/
| T//Rtmpm2tVkx/sourcecpp_f9e75ec42b87/sourceCpp_220.so':
|   dlopen(/var/folders/12/bqytpkx93w97r3s3_h9q9k_00000gn/T//Rtmpm2tVkx/
| sourcecpp_f9e75ec42b87/sourceCpp_220.so, 6): Symbol not found:
| __ZN4Rcpp4wrapINSt3__124uniform_int_distributionIiEEEEP7SEXPRECRKT_
|   Referenced from: /var/folders/12/bqytpkx93w97r3s3_h9q9k_00000gn/T//Rtmpm2tVkx
| /sourcecpp_f9e75ec42b87/sourceCpp_220.so
|   Expected in: flat namespace
|  in /var/folders/12/bqytpkx93w97r3s3_h9q9k_00000gn/T//Rtmpm2tVkx/
| sourcecpp_f9e75ec42b87/sourceCpp_220.so
| 
|    5. I am working on OS X Mavericks and use clang-omp compiler
| 
| Can somebody possibly direct me to what I may be doing wrong here.  Apologies
| if the question seems too basic to you.

We attempt to stress in our presentations that _everything_ really happens
within the confines of

   SEXP .Call("somefunc", SEXP a, SEXP b, SEXP c, ...)

as this is the _only_ interface that R offers.

We have vignettes expanding on this -- but in short you failed to convert a
type only you and the compiler know to one which R and Rcpp know too.  There
are means to do this.  But a faster and easier way may just be to copy into a
standard STL container (std::vector<double>, say).

Dirk

| 
| Thank you in advance.
| 
| Anguel
| 
| 
| 
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-- 
http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org

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