[Rcpp-devel] starter

[f.krah at mailbox.org]

Thanks Romain,

this error is fine now, however, now I run into new…
I took the example code from this <http://dirk.eddelbuettel.com/papers/rcpp_rfinance_may2015.pdf> presentation of Dirk


> Rcpp::sourceCpp("src/par_example.cpp")
par_example.cpp:26:21: error: member initializer 'output' does not name a non-static data member or base class
    : input(input), output(output) {}
                    ^~~~~~~~~~~~~~
par_example.cpp:31:5: error: use of undeclared identifier 'output'
    output.begin() + begin,
    ^
2 errors generated.
make: *** [par_example.o] Error 1


Hope this is as easily solved as the before error.

Cheers, Franz




> On 31 May 2017, at 12:26, Romain Francois <romain at r-enthusiasts.com> wrote:
> 
> You can add this somewhere on top of your cpp file 
> 
> // [[Rcpp::depends(RcppParallel)]]
> 
> Romain
> 
>> Le 31 mai 2017 à 12:22, f.krah at mailbox.org <mailto:f.krah at mailbox.org> a écrit :
>> 
>> Hi all,
>> 
>> I am very new to Rcpp and I wrote a function which I now want to parallelize.
>> The function is working fine, and is much faster than in R, however, it really is slow for bigger datasets.
>> 
>> Since the function is running I don’t need to explain what it does, however, it is has 
>> 3 nested for loops. It loops through columns and within each column if loops through the rows and in a third loop produces pair comparisons… 
>> 
>> So the parallelisation should parallelize the column loop.
>> 
>> I found the RcppParallel package and for the beginning wanted to run on of the example to understand the
>> workflow first. However, I already have issues running the code below:
>> 
>> following is sourced with: Rcpp::sourceCpp("src/par_example.cpp")
>> However, I get the error: 
>> 
>> par_example.cpp:6:10: fatal error: 'RcppParallel.h' file not found
>> #include <RcppParallel.h>
>>          ^
>> 1 error generated.
>> make: *** [par_example.o] Error 1
>> 
>> I would much appreciate if someone could give me a start with this!
>> 
>> Cheers, 
>> Franz
>> 
>> 
>> 
>> #include <Rcpp.h>
>> 
>> using namespace Rcpp;
>> #include <cmath>
>> #include <algorithm>
>> #include <RcppParallel.h>
>> 
>> // [[Rcpp::export]]
>> NumericMatrix matrixSqrt(NumericMatrix orig) {
>>   // allocate the matrix we will return
>>   NumericMatrix mat(orig.nrow(), orig.ncol());
>>   // transform it
>>   std::transform(orig.begin(), orig.end(), mat.begin(), ::sqrt);
>>   // return the new matrix
>>   return mat;
>> }
>> 
>> 
>> using namespace RcppParallel;
>> struct SquareRoot : public Worker {
>>   const RMatrix<double> input;
>>   // source matrix RMatrix<double> output; // destination matrix
>>   // initialize with source and destination
>>   SquareRoot(const NumericMatrix input, NumericMatrix output)
>>     : input(input), output(output) {}
>>   // take the square root of the range of elements requested
>>   void operator()(std::size_t begin, std::size_t end) { std::transform(input.begin() + begin,
>>     input.begin() + end,
>>     output.begin() + begin,
>>     ::sqrt);
>>   }
>> };
>> 
>> // [[Rcpp::export]]
>> NumericMatrix parallelMatrixSqrt(NumericMatrix x) {
>>   // allocate the output matrix
>>   NumericMatrix output(x.nrow(), x.ncol());
>>   // SquareRoot functor (pass input and output matrixes)
>>   SquareRoot squareRoot(x, output);
>>   // call parallelFor to do the work
>>   parallelFor(0, x.length(), squareRoot);
>>   // return the output matrix
>>   return output; }
>> 
>> 
>> 
>> _______________________________________________
>> Rcpp-devel mailing list
>> Rcpp-devel at lists.r-forge.r-project.org <mailto:Rcpp-devel at lists.r-forge.r-project.org>
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> 

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