[Rcpp-devel] problem compiling with const in RcppEigen

Douglas Bates bates at stat.wisc.edu
Thu Jan 31 21:38:00 CET 2013


Sorry but I am still struggling (even after reformatting the source code)
to understand what the problem is.  For one thing it is not clear to me
what the Cm_class is for.

The fundamental rule for me is that I always declare functions like

//[[Rcpp::Export]]
Eigen::VectorXd testfunc(const MapVecd ytrait, const MapMatd xmat) {
   ...
}

If you need to get a pointer to the contents of the matrix you could use a
const_cast but in that case I don't understand why you would use the Eigen
classes.  If all you want is the dimensions and a pointer to the contents
you should use NumericMatrix class.



On Thu, Jan 31, 2013 at 1:27 PM, M A <markoilcan at gmail.com> wrote:

> Right. The problem comes up because of the constructor with one of my
> classes. Here is a slightly extended minimal example:
>
> // [[Rcpp::depends(RcppEigen)]]
>
> #include <RcppEigen.h>
> #include <Rcpp.h>
>
> typedef Eigen::Map<Eigen::VectorXd> MapVecd;
> typedef Eigen::Map<Eigen::MatrixXd> MapMatd; // (A). This one works
> with (1) below
> //typedef Eigen::Map<const Eigen::MatrixXd> MapMatd; // (B). This one
> fails with (1) below
>
> class Cm_class {
> public:
>     const MapMatd c_matrix;
>
>     //Cm_class( double *p_pdmat, const int nr, const int nc ) : //
> Works with (A) or (B)
>     Cm_class( const double *p_pdmat, const int nr, const int nc ) : //
> Works with (B) fails with (A)
>         c_matrix(p_pdmat, nr, nc) {}
> };
>
> //Eigen::VectorXd testfunc(const MapVecd ytrait, MapMatd xmat) { //
> (1). This only works with (A)
> // [[Rcpp::export]]
> Eigen::VectorXd testfunc(const MapVecd ytrait) {
>
>     return ytrait;
> }
>
> I really want testfunc to be as in (1) where xmat gets mapped into a
> double matrix, though I take it out above for simplicity. I have my
> class constructor taking a const double*, but that fails with the
> typedef (A), the way you recommend. To get that constructor
> initialization to work I have to use typedef (B), but that causes
> failure with (1), which is what I was originally writing about. I can
> certainly work around this by removing the const from the double* in
> the class constructor, etc, but I guess there's the larger question of
> whether the RcppEigen 'as' function should be able to form an
> Eigen::Map<const Eigen::MatrixXd>. Thanks for the info regarding the
> point of failure.
>
> Mark A
>
> On Thu, Jan 31, 2013 at 11:34 AM, Douglas Bates <bates at stat.wisc.edu>
> wrote:
> > I should check the syntax before sending the message.
> >
> > On Thu, Jan 31, 2013 at 11:30 AM, Douglas Bates <bates at stat.wisc.edu>
> wrote:
> >>
> >> 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);
> >
> >
> > That should be
> >
> > const mMat M = as<mMat>(mat_from_R);
> >
> > Well, at least I think so.
> >
> > The bottom line is that I find it easier to use const in the declaration
> of
> > an instance of a class, not in the typedef.
> >>
> >>
> >> 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 <markoilcan at 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
> >>> _______________________________________________
> >>> Rcpp-devel mailing list
> >>> Rcpp-devel at lists.r-forge.r-project.org
> >>>
> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
> >>
> >>
> >
>
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