dautil.cpp

//#include "Rstaff.h"
#include <vector>
#include <string>
#include <fstream>
#include <sstream>

#include "dautil.h"

#ifdef __cplusplus
extern "C" {
#endif

      SEXP extract_text_file_column_cpp(SEXP Filename, SEXP Whichcol)
      {
            std::string filename = CHAR(STRING_ELT(Filename,0));
            int ncols = (int) LENGTH(Whichcol);
            std::vector<int> whichcol(ncols);
            int maxcol = 0;
            for (int i=0;i<ncols;i++)
            {
                  whichcol[i] = (int) INTEGER(Whichcol)[i];
                  if (whichcol[i]>maxcol) maxcol=whichcol[i];
            }
            std::vector<std::string> outstrings;

            std::ifstream filetoread (filename.c_str());
            if (!filetoread) {
                  error_R("can not open file '%s'\n\n",filename.c_str());
                  return R_NilValue;
            }

            std::string tmpstr;
            while (getline(filetoread,tmpstr))
            {
                  std::istringstream datas (tmpstr);
                  std::string substr;
                  std::vector<std::string> tmpvec;
                  for (int i=0;i<=maxcol;i++) {
                        datas >> substr;
                        tmpvec.push_back(substr);
                  }
                  for (int i=0;i<ncols;i++) {
                        //Rprintf("%i %i %s\n",i,whichcol[i],tmpvec[whichcol[i]].c_str());
                        outstrings.push_back(tmpvec[whichcol[i]]);
                  }
            }

            SEXP ret;
            PROTECT(ret = allocVector(STRSXP, (R_len_t) outstrings.size()));
            for (unsigned long int i = 0;i<outstrings.size();i++) SET_STRING_ELT(ret, i, mkChar(outstrings[i].c_str()));
            UNPROTECT(1);
            return ret;
      }


#ifdef __cplusplus
}
#endif