Le 05/06/13 15:37, Toni Giorgino a écrit :
Dears,
thanks. In fact I've found the problem while looking for a workaround to
the push_back() slowness (used here for convenience only). The
workaround was to preallocate the List, then discard the unneeded
portion, for which I looked into erase(). This was many orders of
magnitude faster.
The single-argument erase() also seems to behave unexpectedly (below).
Also fixed, in rev 4333.
Best
Toni
#include <Rcpp.h>
#include <iostream>
// [[Rcpp::export]]
SEXP truncateTest2() {
using namespace std;
using namespace Rcpp;
Rcpp::List l;
std::vector<int> v;
for (int i=1; i<=10; i++) {
v.push_back(i);
l.push_back(i);
}
// Attempt truncation in another way
vector<int>::iterator vi=v.begin()+1;
while(vi!=v.end())
vi=v.erase(vi); // This works
cout << "std::vector left with " << v.size() << endl;
Rcpp::List::iterator li=l.begin()+1;
while(li!=l.end())
li=l.erase(li); // This doesn't
cout << "Rcpp::List left with " << l.size() << endl;
return(R_NilValue);
}
On Wed, Jun 5, 2013 at 2:50 PM, Romain Francois
<rom...@r-enthusiasts.com <mailto:rom...@r-enthusiasts.com>> wrote:
Thanks. I'll have a look.
Le 05/06/13 14:09, Toni Giorgino a écrit :
Dears,
I am a newbie to Rcpp. I may have found an off-by-one
inconsistency in
the handling of List::erase(iter1,iter2) operation with respect
to its
homologous in the STL (which I suppose is intended to mimic).
In STL,
iter2 can be the container's .end(); in Rcpp, the same gives an
out of
boundary error. (See below)
Thanks for the incredible package. Best
Test case...
#include <Rcpp.h>
#include <iostream>
// [[Rcpp::export]]
SEXP truncateTest() {
BEGIN_RCPP
using namespace std;
Rcpp::List l;
std::vector<int> v;
for (int i=1; i<=10; i++) {
v.push_back(i);
l.push_back(i);
}
v.erase(v.begin()+5,v.end()-1)__;
l.erase(l.begin()+5,l.end()-1)__; // ?
cout << "std::vector left with " << v.size() << endl;
cout << "Rcpp::List left with " << l.size() << endl;
END_RCPP
}
/*** R
# library(Rcpp)
# sourceCpp("truncateTest.cpp")
# truncateTest()
# #prints 6 and 5
*/
--
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
R Graph Gallery: http://gallery.r-enthusiasts.__com
<http://gallery.r-enthusiasts.com>
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--
Toni
--
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
R Graph Gallery: http://gallery.r-enthusiasts.com
blog: http://blog.r-enthusiasts.com
|- http://bit.ly/Zs97qg : highlight 0.4.1
`- http://bit.ly/10X94UM : Mobile version of the graph gallery
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