[Rcpp-devel] Rcpp:integer class?

[Gabor Grothendieck]

On Tue, Dec 21, 2010 at 12:23 PM, Cedric Ginestet
<c.ginestet05 at googlemail.com> wrote:
> Dear Rcpp experts,
>
> I am trying to find a way a single integer to a function. See the code
> below. I am here obliged to translage v1 as an IntegerVector and then to
> select only its first argument. Is there a better way of doing this, where I
> don't have to declare an entire vector for such a task?
>
> ###########################################
> src2 <- '
>   IntegerVector x1(v1);
>   IntegerMatrix xD(D);
>   IntegerVector Drow(xD.ncol());
>   for(int i=0; i<xD.ncol(); i++) Drow[i]=xD(x1[0],i);
> return Drow;
> '
> rowExtraction <-
> cxxfunction(signature(D="matrix",v1="integer"),body=src2,plugin="Rcpp",verbose=TRUE)
> rowExtraction(D,1)
> ############################################
>

Try this:

src2 <- '
  int x1 = as<int>(v1);
  IntegerMatrix xD(D);
  IntegerVector Drow(xD.ncol());
  for(int i=0; i<xD.ncol(); i++) Drow[i]=xD(x1,i);
return Drow;
'
rowExtraction <-
cxxfunction(signature(D="matrix",v1="integer"),body=src2,plugin="Rcpp",verbose=TRUE)
rowExtraction(matrix(1:25,5),1)


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