[Rcpp-devel] [R] Error using Rcpp

[Abhisek]

Many thanks Romain!  It worked.  And thanks for pointing out the errors.

best
abhisek

On Thu, Mar 25, 2010 at 12:45 PM, Romain Francois
<romain at r-enthusiasts.com>wrote:

> Le 25/03/10 13:16, Abhisek a écrit :
>
>
>> Hi, Im not sure if this is the right place to post this.
>>
>
> It is not. The Rcpp-devel mailing list is the right place:
> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
>
>
>  I am using Xubuntu
>> Karmic Koala and am trying to use the Rcpp package.  I am testing it using
>> a
>> simple code that takes in a vector and adds 1 to each element:
>>
>> #include<Rcpp.h>
>>
>> // This file takes in a vector and adds one to each entry
>> RcppExport SEXP addone(SEXP vec){
>>
>>     // create a local copy of vec
>>     Rcpp::NumericVector orig(vec);
>>
>>     // create an output vector
>>     Rcpp::NumericVector vecout(orig.size());
>>
>>     for(i=0;i<orig.size();i++) {
>>         vecout[i] = orig[i]+1;
>>     }
>>
>>     Rcpp::Pairlist
>> res(Rcpp::Named("result",vecout),Rcpp::Named("original",orig));
>>
>>     return res;
>> }
>>
>
> You need some flags set up :
>
> export PKG_LIBS=`Rscript -e "Rcpp:::LdFlags()"`
> export PKG_CXXFLAGS=`Rscript -e "Rcpp:::CxxFlags()"`
>
> R CMD SHLIB addone.cpp
>
> also, your code is not correct since the i variable is not declared, so I
> get this when I try to compile it:
>
> addone.cpp: In function ‘SEXPREC* addone(SEXPREC*)’:
> addone.cpp:12: error: ‘i’ was not declared in this scope
> make: *** [addone.o] Error 1
>
>
> The inline package can help you with this when prototyping your code, check
> the cfunction in the inline package, specifically its arguments "verbose"
> and "Rcpp".
>
>
>
>
>
> Personally I would code this using stl algorithms rather than raw looping:
>
> #include <Rcpp.h>
>
> template <typename T>
> inline T add_one( T x){
>        return x + 1 ;
>
> }
>
> // This file takes in a vector and adds one to each entry
> RcppExport SEXP addone(SEXP vec){
>
>    // original object
>    Rcpp::NumericVector orig(vec);
>
>    // output vector
>
>    Rcpp::NumericVector vecout(orig.size());
>
>    std::transform(
>        orig.begin(), orig.end(),
>        vecout.begin(),
>        add_one<double> ) ;
>
>    return vecout ;
> }
>
>
> or maybe you don't even have to write the tedious add_one template and you
> can do it like this:
>
>
> #include <Rcpp.h>
>
> // This file takes in a vector and adds one to each entry
> RcppExport SEXP addone(SEXP vec){
>
>    // original object
>    Rcpp::NumericVector orig(vec);
>
>    // output vector
>
>    Rcpp::NumericVector vecout(orig.size());
>
>    std::transform(
>        orig.begin(), orig.end(),
>        vecout.begin(),
>        std::bind2nd( std::plus<double>(), 1.0 )
>        ) ;
>
>    return vecout ;
>
> }
>
>
>  I then try to use - R CMD SHLIB addone.cpp
>> that didnt work.  the error said there was no such file  - "Rcpp.h" .
>> Then i came across Dirk Eddelbeutel's beamer presentation and followed the
>> suggestion to copy Rcpp.h to /usr/loca/include and libRcpp.so to
>> /usr/local/lib
>> Then i tried R CMD SHLIB addone.cpp again but got many errors.  Here is a
>> small selection:
>>
>> /usr/local/include/Rcpp.h:34:32: error: RcppDatetimeVector.h: No such file
>> or directory
>> /usr/local/include/Rcpp.h:35:23: error: RcppFrame.h: No such file or
>> directory
>> /usr/local/include/Rcpp.h:36:26: error: RcppFunction.h: No such file or
>> directory
>> /usr/local/include/Rcpp.h:37:22: error: RcppList.h: No such file or
>> directory
>>
>> could someone help?  im afraid im new both to linux and Rcpp!
>>
>> best,
>> abhisek
>>
>
>
> --
> Romain Francois
> Professional R Enthusiast
> +33(0) 6 28 91 30 30
> http://romainfrancois.blog.free.fr
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>
>
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