[Rcpp-devel] starter

[f.krah at mailbox.org]

Darn… it thought it is a copy error but couldn't find the fault!!
Thanks a lot. Not it is working. 
Hope I can now transfer the stuff to my 3-nest-loop..

Cheers, 
Franz


> On 31 May 2017, at 12:46, Romain Francois <romain at r-enthusiasts.com> wrote:
> 
> 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 <mailto: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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