[Rcpp-commits] r3930 - pkg/Rcpp/inst/examples/Misc

[noreply at r-forge.r-project.org]

Author: edd
Date: 2012-11-10 21:00:39 +0100 (Sat, 10 Nov 2012)
New Revision: 3930

Added:
   pkg/Rcpp/inst/examples/Misc/newFib.r
Log:
simple attributes version of the fibonacci comparison


Added: pkg/Rcpp/inst/examples/Misc/newFib.r
===================================================================
--- pkg/Rcpp/inst/examples/Misc/newFib.r	                        (rev 0)
+++ pkg/Rcpp/inst/examples/Misc/newFib.r	2012-11-10 20:00:39 UTC (rev 3930)
@@ -0,0 +1,32 @@
+#!/usr/bin/r
+
+## New and shorter version of Fibonacci example using Rcpp 0.9.16 or later features
+## The the sibbling file 'fibonacci.r' for context
+
+require(Rcpp)                           # no longer need inline
+
+## R version
+fibR <- function(seq) {
+    if (seq < 2) return(seq)
+    return (fibR(seq - 1) + fibR(seq - 2))
+}
+
+## C++ code
+cpptxt <- '
+int fibonacci(const int x) {
+   if (x < 2) return(x);
+   return (fibonacci(x - 1)) + fibonacci(x - 2);
+}'
+
+## C++ version
+fibCpp <- cppFunction(cpptxt)           # compiles, load, links, ...
+
+## load rbenchmark to compare
+library(rbenchmark)
+
+N <- 35     ## same parameter as original post
+res <- benchmark(fibR(N), fibCpp(N),
+                 columns=c("test", "replications", "elapsed", "relative"),
+                 order="relative", replications=1)
+print(res)  ## show result
+