[R] building a quicksort function in rcpp

[Uwe Ligges]

Actually sort() is already there ....

Best,
Uwe Ligges



On 24.07.2015 17:22, Martin Tully wrote:
> Hi I am using RCPP to build a C++ function for quicksort called qsort.
> This function is compiled and loaded through the cxxfunction in R
> I am getting the message in R error: no matching function for call to
> 'qsort(int*&)' The code is below.
> It will not run for me and I was wondering if you could help?
>
>
>
> library(Rcpp)
> library(inline)
>
>
>      incl <- 'int qsort(int xx[], int left, int right) {
>
>              int i = left,
>              j = right;
>              int tmp;
>              int pivot = xx[(left + right) / 2];
>
>              /* partition */
>                while (i <= j) {
>                  while (xx[i] < pivot)
>                    i++;
>                  while (xx[j] > pivot)
>                    j--;
>                  if (i <= j) {
>                    tmp = xx[i];
>                    xx[i] = xx[j];
>                    xx[j] = tmp;
>                    i++;
>                    j--;
>                  }
>                }
>
>              /* recursion */
>                if (left < j){
>                  qsort(xx, left, j);
>                }
>              if (i < right){
>                qsort(xx, i, right);
>              }
>
>          return (qsort(xx));
>            }
>            '
>
>            sortCpp <- cxxfunction(signature( x = "integer",left = "integer",
>                                              right = "integer"),
>                                   body = 'IntegerVector arr(x);
>                                           int a = as<int>(left);
>                                           int b = as<int>(right);
>                                          return wrap(qsort(arr));',
>                                   include = incl,
>                                   plugin = "Rcpp",
>                                   verbose = TRUE)
>
> 	[[alternative HTML version deleted]]
>
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