Message-ID: <CAD6866F-64CE-4D4B-B0EF-03EE32273D67@uni-bonn.de>
Date: 2013-03-06T07:32:18Z
From: Simon Zehnder
Subject: [Rcpp-devel] Initiate NumericMatrix in class constructor from S4 slot
In-Reply-To: <5006F817-370D-4279-9CC9-2F7BE133DE8A@r-enthusiasts.com>
Hi Romain,
first let me thank you for the very fast and informative answer!
I suppose, as SEXP is a pointer, that these attempts reuse the memory allocated in R, right? Further, I presume, that I proceed in the same way for lists from R to Rcpp, don't I?
In regard to the initialisation list:
I have in my class over 10 different objects, so up to now I refused to use the initialising list. But you are right, that in regard to performance (copying etc.) the
initialising list is indisputable. So I gonna use it.
Thanks again Romain!
Best
Simon
On Mar 6, 2013, at 8:23 AM, Romain Francois <romain at r-enthusiasts.com> wrote:
> There is no constructor of Matrix tht takes a SlotProxy. You can do it in two steps perhaps.
>
> SEXP tmp = classS4.slot("M_R") ;
> M = tmp ;
>
> Or use a specific cast:
>
>> M((SEXP)classS4.slot("M_R"));
>
> In any case, you should use an initialisation list in your constructor anyway, something like:
>
>> FirstClass::FirstClass(Rcpp::S4& classS4) : M( (SEXP)classS4.slot("M_R")) {}
>
> Hiwever, i will add the missing constructor if this does not break anything else.
>
> Romain
>
> Le 6 mars 2013 ? 08:14, Simon Zehnder <szehnder at uni-bonn.de> a ?crit :
>
>> Dear Rcpp-Devels,
>>
>> I am a little confused right now with the following setting:
>>
>> I have a C++ class with for example the following header
>>
>> #include <RcppArmadillo.h>
>>
>> class FirstClass {
>>
>> public:
>> Rcpp::NumericMatrix M;
>>
>> FirstClass(Rcpp::S4& classS4);
>> ~FirstClass();
>> }
>>
>> Then, in the .cc file I have:
>>
>> #include <RcppArmadillo.h>
>> #include "FirstClass.h"
>>
>> FirstClass::FirstClass(Rcpp::S4& classS4) {
>>
>> M(classS4.slot("M_R")); // array M_R in R
>> };
>>
>> FirstClass::~FirstClass(){};
>>
>> Now, my compiler always gives me an error:
>>
>> error: no match for call to ?(Rcpp::NumericMatrix {aka Rcpp::Matrix<14>}) (Rcpp::RObject::SlotProxy)?
>>
>>
>> Do I have to create the Matrix in the constructor differently? I want to reuse memory allocated in R. Further, could the error be triggered by M_R being an array in R?
>>
>> Best
>>
>> Simon
>>
>>
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