[Rcpp-devel] Manipulation of IntegerVector

[Sven E. Templer]

hi,

you should change the line
matched[j+1] = tmp;
to
matched[j-1] = tmp;
to get rid of your error.


require(Rcpp)
require(inline)
sourceCpp(code='
  #include <Rcpp.h>
  using namespace Rcpp;
  // [[Rcpp::export]]
  List createVectorList_Numeric_cpp(NumericMatrix df) {
  CharacterVector rownames = VECTOR_ELT(df.attr("dimnames"), 0);
  CharacterVector colnames = VECTOR_ELT(df.attr("dimnames"), 1);
  // Check Dimnames
  if (df.nrow() != rownames.size() ) {
    throw Rcpp::exception("Dimensions and corrosponding names differ
in length");
  }
  List vectorList(df.ncol());
  for(int i = 0; i < df.ncol(); i++){
    NumericVector sorted_vec = df(_,i);
    sorted_vec=sorted_vec.sort();
    NumericVector one_col = df(_,i);
    IntegerVector matched = match(sorted_vec, one_col);
    for(int j = 0; j < (matched.size() - 1); j++){
      if( matched[j] >= matched[j+1] ){
        matched[j-1] = matched[j]+1;
      }
    }
    sorted_vec.attr("names")=rownames[matched-1];
    vectorList[i]=sorted_vec;
  }
  vectorList.attr("names") = colnames;
  CharacterVector classIDs = CharacterVector::create("VectorList", "list");
  vectorList.attr("class") = classIDs;
  return vectorList;
}
')

m <- matrix(c(2,3,1),3,1,dimnames=
list(letters[1:3],1))
createVectorList_Numeric_cpp(m)

$`1`
c a b
1 2 3

attr(,"class")
[1] "VectorList" "list"

IMPORTANT:
you will get an error matching names when there are duplicated values.
probably you don't want this...:

m <- matrix(c(2,3,2),3,1,dimnames=list(letters[1:3],1))
createVectorList_Numeric_cpp(m)

$`1`
a a b
2 2 3

attr(,"class")
[1] "VectorList" "list"

Sincerely,
Sven

(+1 for a .sort() that sorts also names...)

@sameer: sorry sending to you twice.

On 11 July 2014 10:19, Mario Deng <mariodeng at googlemail.com> wrote:
> Hello everyone,
>
> I still struggle with Rcpp, I hope you guys are patient.
>
> The problem occurs here:
>
> IntegerVector matched = match(sorted_vec, one_col);
>   for(int j = 0; j < (matched.size() - 1); j++){
>     if( matched[j] >= matched[j+1] ){
>       matched[j+1] = matched[j]+1;
>     }
>   }
>
> I can access matched[j+1] for reading (tested with Rcout), but when I try to modify it, "matched[j+1] = matched[j]+1" the complete R-Instance crashes.
> My first thought was, that there is something wrong with mit indexing. But I can set the elements with a constant int like "matched[j+1] = 1", also I am able to do something like "int foobar = matched[j]+1".
>
> But when I do "matched[j+1] = matched[j]+1;" everything crashes, I don't get any error informations etc. Also, is there a way to avoid that the R instance/RStudio crashes?
>
> With best regards,
>
> Mario
>
> Please find the complete code below.
>
> // [[Rcpp::export]]
> List createVectorList_Numeric_cpp(NumericMatrix df) {
>   CharacterVector rownames = VECTOR_ELT(df.attr("dimnames"), 0);
>   CharacterVector colnames = VECTOR_ELT(df.attr("dimnames"), 1);
>   // Check Dimnames
>   if (df.nrow() != rownames.size() ) {
>     throw Rcpp::exception("Dimensions and corrosponding names differ in length");
>   }
>   List vectorList(df.ncol());
>   for(int i = 0; i < df.ncol(); i++){
>     NumericVector sorted_vec = df(_,i);
>     sorted_vec=sorted_vec.sort();
>     NumericVector one_col = df(_,i);
>     IntegerVector matched = match(sorted_vec, one_col);
>     for(int j = 0; j < (matched.size() - 1); j++){
>       if( matched[j] >= matched[j+1] ){
>         const int tmp = matched[j]+1;
>         matched[j+1] = tmp;
>       }
>     }
>     sorted_vec.attr("names")=rownames[matched-1];
>     vectorList[i]=sorted_vec;
>   }
>   vectorList.attr("names") = colnames;
>   CharacterVector classIDs = CharacterVector::create("VectorList", "list");
>   vectorList.attr("class") = classIDs;
>   return vectorList;
> }
> __
> MD
> mariodeng at googlemail.com
>
>
>
>
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