[Rcpp-devel] starter

[Romain Francois]

This looks like a copy and paste mistake. I can definitely see this line on the slide 57: 
RMatrix<double> output; 

Anyway, the example is there: 
http://gallery.rcpp.org/articles/parallel-matrix-transform/ <http://gallery.rcpp.org/articles/parallel-matrix-transform/>

Romain

> Le 31 mai 2017 à 12:42, f.krah at mailbox.org a écrit :
> 
> 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 <mailto: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>
>>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel <https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel>
> 

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