Code optimization, an Rcpp solution

November 10, 2011

(This article was first published on Romain Francois, Professional R Enthusiast - Tag - R, and kindly contributed to R-bloggers)

Tony Breyal woke up an old code optimization problem in this blog post, so I figured it was time for an Rcpp based solution

This solutions moves down Henrik Bengtsson’s idea (which was at the basis of attempt 10) down to C++. The idea was to call sprintf less than the other solutions to generate the strings “001”, “002”, “003”, …

We can benchmark this version using the rbenchmark package:

> library(rbenchmark)
> n <- 2000
> benchmark(
+     generateIndex10(n), 
+     generateIndex11(n),
+     generateIndex12(n), 
+     generateIndex13(n),
+     generateIndex14(n),
+     columns = 
+        c("test", "replications", "elapsed", "relative"),
+     order = "relative",
+     replications = 20
+ )
                test replications elapsed relative
5 generateIndex14(n)           20  21.015 1.000000
3 generateIndex12(n)           20  22.034 1.048489
4 generateIndex13(n)           20  23.436 1.115203
2 generateIndex11(n)           20  23.829 1.133904
1 generateIndex10(n)           20  30.580 1.455151

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