Advanced R

17

Optimising code

“Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered.”

— Donald Knuth.

Optimising code to make it run faster is an iterative process:

1. Find the biggest bottleneck (the slowest part of your code).
2. Try to eliminate it (you may not succeed but that’s ok).
3. Repeat until your code is “fast enough.”

This sounds easy, but it’s not.

Even experienced programmers have a hard time identifying bottlenecks in their code. Instead of relying on your intuition, you should profile your code: use realistic inputs and measure the run-time of each individual ...