R Recipe
Reordering Columns in a Flexible Way

The paper helicopter experiment
The paper helicopter is one of the devices to explain about design of experiments. The aim is to create the longest flying paper helicopter by means of experimental design. Paper helicopters are a nice example, because they are cheap to make, easy to test landing time and sufficient variables to make it non obvious. Rather than make and measure my own helicopters, I decided to use data from the internet. In this post I use data from williamghunter.net and http://www.rose-hulman.edu. There is more data on the internet, but these two are fairly similar. Both use a fractional factorial design of 16 runs and they have the same variables. However, a quick check showed that these were different results and, very important, the aliasing structure was different.

Python: Counter – ValuEerror: Too Many Values to Unpack
I recently came across Python’s Counter tool which makes it really easy to count the number of occurrences of items in a list.