[Rcpp-devel] Use size_t rather than int for vector sizes and indexing?

Chuck,

Internally, R is using 4-byte integers for indexing, and the length of
a vector is thus constrained to 2-billion-ish elements.  Two ways
around this include packages ff and
bigmemory, for example, or relying on database-like queries.  However,
the resulting objects can't be used with standard R functions (with
some special exceptions).

Jay


On Wed, Apr 13, 2011 at 2:05 PM,  <chuck at chuckcode.com> wrote:

Hi All,

Thanks to Dirk Eddelbuettel and the other contributors for such a
wonderful package. Rcpp really transforms the way that I've been able

incorporate c++ code into R. Makes it possible to speed up the critical
computations while keeping all the great flexibility and features of R.

I've run into a problem lately with particularly large vectors in Rcpp.

seem to be overflowing when my vectors get larger than 2^31 elements on

64 bit system. It looks from the code of both the classic (included
below)
and the newer versions as though this is due to using ints rather than
something like size_t (http://en.wikipedia.org/wiki/Size_t) as the type
for
size and indexing into the vector. It looks like RcppResultsSet's add()
functions may also be using ints.

Curious to know if there is a particular reason for using ints rather
than
something like size_t and if the project managers would be open to
changing
to accomodate larger vectors.

Thanks,
-Chuck Sugnet

template <typename T>
class RcppVector {
public:
? ? ? ?typedef T* iterator ;
? ? ? ?typedef const T* const_iterator ;

? ?RcppVector(SEXP vec);
? ?RcppVector(int len);
? ?int size() const;
? ?T& operator()(int i) const;
? ?T *cVector() const;
? ?std::vector<T> stlVector() const;

? ?inline const_iterator begin() const { return v ; }
? ?inline const_iterator end() const { return v + len ; }

? ?inline iterator begin(){ return v ; }
? ?inline iterator end(){ return v + len ; }

private:
? ?int len;
? ?T *v;
};