Dear Listmembers, wanting to learn more about ALTREP I wrote the following function to extract a subsequence from an integer vector:
#include <Rinternals.h> SEXP integer_get_region(SEXP _x, SEXP _i, SEXP _n) { int i = INTEGER(_i)[0]; int n = INTEGER(_n)[0]; SEXP result = PROTECT(Rf_allocVector(INTSXP, n)); INTEGER_GET_REGION(_x, i, n, INTEGER(result)); UNPROTECT(1); return result; } For "shorter" vectors, the result is as expected: > dyn.load("altrep_int_region.so") > .Call("integer_get_region", 1:1e9, 0L, 10L) [1] 1 2 3 4 5 6 7 8 9 10 But not for "longer" vectors: > .Call("integer_get_region", 1:1e10, 0L, 10L) [1] 0 1072693248 0 1073741824 0 1074266112 [7] 0 1074790400 0 1075052544 Am I doing something wrong or is this a bug? I am using > R.version.string [1] "R version 3.5.2 (2018-12-20)" Thanks Ralf -- Ralf Stubner Senior Software Engineer / Trainer daqana GmbH Dortustraße 48 14467 Potsdam T: +49 331 23 61 93 11 F: +49 331 23 61 93 90 M: +49 162 20 91 196 Mail: ralf.stub...@daqana.com Sitz: Potsdam Register: AG Potsdam HRB 27966 Ust.-IdNr.: DE300072622 Geschäftsführer: Dr.-Ing. Stefan Knirsch, Prof. Dr. Dr. Karl-Kuno Kunze
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