Function is_atomic

inst/include/Rcpp/api/meat/is.h:28–28

  namespace internal {

    inline bool is_atomic(SEXP x) { return Rf_length(x) == 1; }
    inline bool is_matrix(SEXP x) {
        SEXP dim = Rf_getAttrib( x, R_DimSymbol);
        return dim != R_NilValue && Rf_length(dim) == 2;