On 10/25/19 5:20 PM, Wang Jiefei wrote: > Thank you, Tomas. I appreciate your help. BTW, could you also add an > explicit type conversion in " ITERATE_BY_REGION_PARTIAL" macro while > you are fixing the bug? C++ compiler does not happy with the implicit > conversion from void* to T* somehow and I have to redefine it before > using the macro.
Yes, C++ requires a cast from void to non-void pointer. Fixed now in R-devel (77331): your example iterator should now work also for the non-compact sequence. Best Tomas > > Best, > Jiefei > > On Fri, Oct 25, 2019 at 11:13 AM Tomas Kalibera > <tomas.kalib...@gmail.com <mailto:tomas.kalib...@gmail.com>> wrote: > > On 10/25/19 11:01 AM, Tomas Kalibera wrote: > > On 10/23/19 6:45 AM, Wang Jiefei wrote: > >> Hi all, > >> > >> I found an unexpected behavior when I was trying to use the macro > >> defined > >> in "R_ext/Itermacros.h" to loop over an atomic vector. Here is a > >> minimum > >> example: > >> > >> C++ code > >> ``` > >> #include "R_ext/Itermacros.h" > >> #define GET_REGION_BUFSIZE 2 > >> //Redefine the macro since C++ is not happy with the implicit type > >> conversion > >> #define ITERATE_BY_REGION_PARTIAL(sx, px, idx, nb, etype, vtype, \ > >> strt, nfull, expr) do { \ > >> const etype *px = (etype*)DATAPTR_OR_NULL(sx); \ > >> if (px != NULL) { \ > >> R_xlen_t __ibr_n__ = strt + nfull; \ > >> R_xlen_t nb = __ibr_n__; \ > >> for (R_xlen_t idx = strt; idx < __ibr_n__; idx += nb) { \ > >> expr \ > >> } \ > >> } \ > >> else ITERATE_BY_REGION_PARTIAL0(sx, px, idx, nb, etype, vtype, \ > >> strt, nfull, expr); \ > >> } while (0) > >> // [[Rcpp::export]] > >> void C_testPrint(SEXP x) { > >> ITERATE_BY_REGION_PARTIAL(x, ptr, idx, nbatch, double, REAL, 1, > 4, { > >> for (R_xlen_t i = 0; i < nbatch; i++) > >> Rprintf("idx: %lld, i: %lld, ptr:%f\n", idx, i, ptr[i]); > > > > You need to index "ptr" by "idx + i", not by "i". Have a look at > how > > the macros are used in R, e.g. printvector.c. > > Actually, the macro should do this for you, we will investigate/fix. > Thanks for the report! > > Best > Tomas > > > > > Best, > > Tomas > > > >> }); > >> } > >> ``` > >> > >> The function C_testPrint loops over its argument x and prints > out one > >> value > >> of x at each loop. The loop starts from the second element and > ends > >> in the > >> fifth element of x. I also redefine the buffer size to see the > effect of > >> it. Here is my R code: > >> > >> R code > >> ``` > >>> C_testPrint(as.numeric(1:10)) > >> idx: 1, i: 0, ptr:2.000000 > >> idx: 1, i: 1, ptr:3.000000 > >> idx: 3, i: 0, ptr:4.000000 > >> idx: 3, i: 1, ptr:5.000000 > >>> C_testPrint(c(1,2,3,4,5,6,7,8,9,10)) > >> idx: 1, i: 0, ptr:1.000000 > >> idx: 1, i: 1, ptr:2.000000 > >> idx: 1, i: 2, ptr:3.000000 > >> idx: 1, i: 3, ptr:4.000000 > >> idx: 1, i: 4, ptr:5.000000 > >> ``` > >> > >> There are two problems in the outputs: > >> 1. The numbers of lines are different > >> 2. The starting indices are not the same. > >> > >> From my understanding, the first output seems correct to me. The > >> second is > >> not unexpected. I believe the differences are due to the > >> accessibility of > >> the data pointer. Did I misunderstand and misuse the macro? Or > is it > >> a bug > >> in R? Here is my session info. My R is a bit outdated but the > macro > >> seems > >> unchanged in R 4.0. Thanks > >> > >> ``` > >>> sessionInfo() > >> R Under development (unstable) (2019-08-22 r77060) > >> Platform: x86_64-w64-mingw32/x64 (64-bit) > >> Running under: Windows >= 8 x64 (build 9200) > >> ``` > >> > >> [[alternative HTML version deleted]] > >> > >> ______________________________________________ > >> R-devel@r-project.org <mailto:R-devel@r-project.org> mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-devel > > > > > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
