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Some of internally used C routines are now exported. This interface should be considered experimental. List of exported C routines and their signatures are provided below in the usage section.


# SEXP DT_subsetDT(SEXP x, SEXP rows, SEXP cols);
# p_DT_subsetDT = R_GetCCallable("data.table", "DT_subsetDT");


Details how to use those can be found in Writing R Extensions manual Linking to native routines in other packages section. An example use with Rcpp:

  dt =
  Rcpp::cppFunction("SEXP mysub2(SEXP x, SEXP rows, SEXP cols) { return DT_subsetDT(x,rows,cols); }",
    include="#include <datatableAPI.h>",
  mysub2(dt, 1:4, 1:4)


Be aware C routines are likely to have less input validation than their corresponding R interface. For example one should not expect DT[-5L] will be equal to .Call(DT_subsetDT, DT, -5L, seq_along(DT)) because translation of i=-5L to seq_len(nrow(DT))[-5L] might be happening on R level. Moreover checks that i argument is in range of 1:nrow(DT), missingness, etc. might be happening on R level too.