The as function in RcppEigen can form an
Eigen::Map<Eigen::MatrixXd>
but doesn't know how to form an
Eigen::Map<const Eigen::MatrixXd>
Generally I find that I confuse myself less when the const is outside the
Eigen::Map. In other words, I use something like
typedef Eigen::Map<Eigen::MatrixXd> mMat;
const mMat M(mat_from_R);
This tells me that M is a mapped MatrixXd object which is constructed from
the SEXP mat_from_R and is read-only.
On Thu, Jan 31, 2013 at 11:01 AM, M A <markoil...@gmail.com> wrote:
> I am compiling some source code using sourceCpp and getting a
> compiling failure when the source has the line with the const keyword
> but no failure when it does not, in the below source.
>
> // file: minimaltest.cpp
> // [[Rcpp::depends(RcppEigen)]]
>
> #include <RcppEigen.h>
> #include <Rcpp.h>
>
> typedef Eigen::Map<Eigen::VectorXd> MapVecd;
> //typedef Eigen::Map<Eigen::MatrixXd> MapMatd; // This one works
> typedef Eigen::Map<const Eigen::MatrixXd> MapMatd; // This one fails
>
> // [[Rcpp::export]]
> Eigen::VectorXd testfunc(const MapVecd ytrait, MapMatd xmat) {
>
> return ytrait;
> }
>
> This is the error:
>
> > sourceCpp("minimaltest.cpp")
> g++ -arch x86_64 -I/Library/Frameworks/R.framework/Resources/include
> -I/Library/Frameworks/R.framework/Resources/include/x86_64 -DNDEBUG
> -I/usr/local/include
>
> -I"/Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include"
>
> -I"/Library/Frameworks/R.framework/Versions/2.15/Resources/library/RcppEigen/include"
> -fPIC -g -O2 -c minimaltest.cpp -o minimaltest.o
> Error in sourceCpp("minimaltest.cpp") :
> Error 1 occurred building shared library.
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp/internal/Exporter.h:
> In constructor ‘Rcpp::traits::Exporter<T>::Exporter(SEXPREC*) [with T
> = Eigen::Map<const Eigen::Matrix<double, -0x00000000000000001,
> -0x00000000000000001, 0, -0x00000000000000001, -0x00000000000000001>,
> 0, Eigen::Stride<0, 0> >]’:
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp/as.h:67:
> instantiated from ‘T Rcpp::internal::as(SEXPREC*,
> Rcpp::traits::r_type_generic_tag) [with T = Eigen::Map<const
> Eigen::Matrix<double, -0x00000000000000001, -0x00000000000000001, 0,
> -0x00000000000000001, -0x00000000000000001>, 0, Eigen::Stride<0, 0>
> >]’
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp/as.h:112:
> instantiated from ‘T Rcpp::as(SEXPREC*) [with T = Eigen::Map<const
> Eigen::Matrix<double, -0x00000000000000001, -0x00000000000000001, 0,
> -0x00000000000000001, -0x00000000000000001>, 0, Eigen::Stride<0, 0>
> >]’
> minimaltest.cpp:35: instantiated from here
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp/internal/Exporter.h:31:
> error: no matching function for call to ‘Eigen::Map<const
> Eigen::Matrix<double, -0x00000000000000001, -0x00000000000000001, 0,
> -0x00000000000000001, -0x00000000000000001>, 0, Eigen::Stride<0, 0>
> >::Map(SEXPREC*&)’
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/RcppEigen/include/Eigen/src/Core/Map.h:164:
> note: candidates are: Eigen::Map<MatrixType, MapOptions,
> StrideType>::Map(typename Eigen::MapBase<Eigen::Map<PlainObjectType,
> MapOptions, StrideType>,
> (Eigen::internal::accessors_level<Eigen::Map<PlainObjectType,
> MapOptions, StrideType> >::has_write_access ? WriteAccessors :
> ReadOnlyAccessors)>::PointerType, typename
> Eigen::internal::traits<Eigen::Map<PlainObjectType, MapOptions,
> StrideType> >::Index, typename
> Eigen::internal::traits<Eigen::Map<PlainObjectType, MapOptions,
> StrideType> >::Index, const StrideType&) [with PlainObjectType = const
> Eigen::Matrix<double, -0x00000000000000001, -0x00000000000000001, 0,
> -0x00000000000000001, -0x00000000000000001>, int MapOptions = 0,
> StrideType = Eigen::Stride<0, 0>]
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/RcppEigen/include/Eigen/src/Core/Map.h:151:
> note: Eigen::Map<MatrixType, MapOptions,
> StrideType>::Map(typename Eigen::MapBase<Eigen::Map<PlainObjectType,
> MapOptions, StrideType>,
> (Eigen::internal::accessors_level<Eigen::Map<PlainObjectType,
> MapOptions, StrideType> >::has_write_access ? WriteAccessors :
> ReadOnlyAccessors)>::PointerType, typename
> Eigen::internal::traits<Eigen::Map<PlainObjectType, MapOptions,
> StrideType> >::Index, const StrideType&) [with PlainObjectType = const
> Eigen::Matrix<double, -0x00000000000000001, -0x00000000000000001, 0,
> -0x00000000000000001, -0x00000000000000001>, int MapOptions = 0,
> StrideType = Eigen::Stride<0, 0>]
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/RcppEigen/include/Eigen/src/Core/Map.h:139:
> note: Eigen::Map<MatrixType, MapOptions,
> StrideType>::Map(typename Eigen::MapBase<Eigen::Map<PlainObjectType,
> MapOptions, StrideType>,
> (Eigen::internal::accessors_level<Eigen::Map<PlainObjectType,
> MapOptions, StrideType> >::has_write_access ? WriteAccessors :
> ReadOnlyAccessors)>::PointerType, const StrideType&) [with
> PlainObjectType = const Eigen::Matrix<double, -0x00000000000000001,
> -0x00000000000000001, 0, -0x00000000000000001, -0x00000000000000001>,
> int MapOptions = 0, StrideType = Eigen::Stride<0, 0>]
>
> /Library/Frameworks/R.framework/Versions/2.15/Resources/library/RcppEigen/include/Eigen/src/Core/Map.h:106:
> note: Eigen::Map<const Eigen::Matrix<double,
> -0x00000000000000001, -0x00000000000000001, 0, -0x00000000000000001,
> -0x00000000000000001>, 0, Eigen::Stride<0, 0> >::Map(const
> Eigen::Map<const Eigen::Matrix<double, -0x00000000000000001,
> -0x00000000000000001, 0, -0x00000000000000001, -0x00000000000000001>,
> 0, Eigen::Stride<0, 0> >&)
> make: *** [minimaltest.o] Error 1
>
> Here is my session info:
> > sessionInfo()
> R version 2.15.2 (2012-10-26)
> Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
>
> locale:
> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
> other attached packages:
> [1] RcppEigen_0.3.1.2 Matrix_1.0-9 lattice_0.20-10 Rcpp_0.10.2
>
> loaded via a namespace (and not attached):
> [1] grid_2.15.2 tools_2.15.2
>
> Note that the g++... portion works fine on the command line, so I
> guess the failure is somewhere in the building of the library. Of
> course I can get around this by not using the const keyword, but why
> is there a problem and what is the right fix?
>
> Thanks,
> Mark A
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