Question

I have written two functions in R and I need to see which is faster so I used system.time. However, the answers are so varied I can’t tell. As its for assessed work I don’t feel I can actually post the code (in case someone corrects it). Both functions call rbinom to generate multiple values and this is the only part that isn’t a simple calculation.

The function time needs to be as fast as possible but both are returning times of anywhere between 0.17 and 0.33. As the mark is 0.14/(my function time) x 10 it’s important I know the exact time.

I have left gcFirst=TRUE as recommended in the R help.

My question is why are the times so inconsistent? Is it most likely to be the functions themselves, my laptop or R?

Answer 1

You probably want to use one of the benchmarking packages

• rbenchmark
• microbenchmark

for this. And even then, variability will always enter. Benchmarking and performance testing is not the most exact science.

Also see the parts on profiling in the “Writing R Extensions” manual.