RcppRNGsExample: Rcpp RNGs example

In RcppExamples: Examples using Rcpp to interface R and C++

Description

Rcpp sugar provides numerous p/q/d/r functions for numerous distributions.

This example shows (in the corresponding C++ code) how to draw from three different distributions and returns a data frame.

Details

The various header file, and the Rcpp sugar vignette, provide full documentation for Rcpp sugar.

The C++ source file corresponding to the this function does the following (inside of a try/catch block):

        Rcpp::RNGScope scope;         		// needed when RNGs are drawn

        int n = Rcpp::as<int>(ns); 		// length vector 
        Rcpp::NumericVector rn = Rcpp::rnorm(n);
        Rcpp::NumericVector rt = Rcpp::rt(n, 1.0);
        Rcpp::NumericVector rp = Rcpp::rpois(n, 1.0);

        // create a new data frame to return drawns
        Rcpp::DataFrame NDF = 
            Rcpp::DataFrame::create(Rcpp::Named("rnorm") =rn,
                                    Rcpp::Named("rt")    =rt,
                                    Rcpp::Named("rpois") =rp);

        // and return old and new in list
        return(NDF);
  

As shown in the example section, provided the seed is reset, the exact same draws can be obtained in R itself – which is important for reproducibility.

Author(s)

Dirk Eddelbuettel and Romain Francois

Examples

  set.seed(42)
  X <- RcppRNGsExample(10L)
  set.seed(42)
  Y <- data.frame(rnorm=rnorm(10),rt=rt(10,1),rpois=rpois(10,1))
  all.equal(X,Y)

RcppExamples documentation built on May 2, 2019, 4:46 p.m.