\name{cdt}

\alias{cdatatable}

\title{ data.table exported C routines }

\description{

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.

}

\usage{

# SEXP DT_subsetDT(SEXP x, SEXP rows, SEXP cols);

# p_DT_subsetDT = R_GetCCallable("data.table", "DT_subsetDT");

}

\details{

Details how to use those can be found in \emph{Writing R Extensions} manual \emph{Linking to native routines in other packages} section.

An example use with \code{Rcpp}:

\preformatted{

dt = data.table::as.data.table(iris)

Rcpp::cppFunction("SEXP mysub2(SEXP x, SEXP rows, SEXP cols) { return DT_subsetDT(x,rows,cols); }",

include="#include <datatableAPI.h>",

depends="data.table")

mysub2(dt, 1:4, 1:4)

}

}

\note{

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

}

\references{

\url{https://cran.r-project.org/doc/manuals/r-release/R-exts.html}

}

\keyword{ data }