[Rcpp-devel] Dirk's benchmarking of code for creation of random binary matrices

[Douglas Bates]

Slightly different results if I clean up the eigenFloor version and
use unif_rand() instead of runif.  The sugar version is still faster,
however.
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> library(inline)
> library(compiler)
> library(rbenchmark)
> 
> n <- 500
> k <- 100
> scott <- function(N, K) {
+     mm <- matrix(0, N, K)
+     apply(mm, c(1, 2), function(x) sample(c(0, 1), 1))
+ }
> scottComp <- cmpfun(scott)
> ted <- function(N, K) {
+     matrix(rbinom(N * K, 1, 0.5), ncol = K, nrow = N)
+ }
> david <- function(m, n) {
+     matrix(sample(0:1, m * n, replace = TRUE), m, n)
+ }
> luis <- function(m, n) {
+      round(matrix(runif(m * n), m, n))
+ }
> armaFloor <- cxxfunction(signature(ns="integer", ks="integer"), plugin = "RcppArmadillo", body='
+    int n = Rcpp::as<int>(ns);
+    int k = Rcpp::as<int>(ks);
+    return wrap(arma::floor(arma::randu(n, k) + 0.5));
+ ')
> sugarFloor <- cxxfunction(signature(ns="integer", ks="integer"), plugin = "Rcpp", body='
+    int n = Rcpp::as<int>(ns);
+    int k = Rcpp::as<int>(ks);
+    Rcpp::RNGScope tmp;
+    Rcpp::NumericVector draws = Rcpp::floor(Rcpp::runif(n*k)+0.5);
+    return Rcpp::NumericMatrix(n, k, draws.begin());
+ ')
> eigenFloor <- cxxfunction(signature(ns="integer", ks="integer"), plugin = "RcppEigen", body='
+    int n(Rf_asInteger(ns)), k(Rf_asInteger(ks));
+    Rcpp::RNGScope tmp;
+    return Rcpp::wrap(Eigen::ArrayXXd(n, k).unaryExpr(std::ptr_fun(rbinary)));
+ ', includes='
+    inline double rbinary(double x) {return std::floor(unif_rand() + 0.5);}
+ ')
Loading required package: lattice

Attaching package: ?RcppEigen?

The following object(s) are masked from ?package:RcppArmadillo?:

    fastLm, fastLmPure

> res <- benchmark(scott(n, k), scottComp(n,k),
+                  ted(n, k), david(n, k), luis(n, k),
+                  armaFloor(n, k), sugarFloor(n, k),
+                  eigenFloor(n, k),
+                  order="relative", replications=100)
> print(res[,1:4])
              test replications elapsed   relative
6  armaFloor(n, k)          100   0.145   1.000000
7 sugarFloor(n, k)          100   0.161   1.110345
8 eigenFloor(n, k)          100   0.189   1.303448
4      david(n, k)          100   0.219   1.510345
3        ted(n, k)          100   0.571   3.937931
5       luis(n, k)          100   0.755   5.206897
2  scottComp(n, k)          100  45.467 313.565517
1      scott(n, k)          100  45.804 315.889655
> 
> proc.time()
   user  system elapsed 
109.610   1.048 110.839