Previously I wrote about latin squares and set a puzzle. We can demonstrate this for an n x n latin square where n = 12 In the above images, the normalised latin square only has 12 different pairs out of a possible 66. The density plot shows the pairings in the lower triangle, grey represents 0. A randomly generated latin square (where all rows and all columns feature 1 to 12 exactly once) is shown where all possible pairs are captured.

As a project idea for a young engineer we wanted to build a Raspberry Pi-based Weather Station . Our last attempt at building something – a sound-responsive LED display – was a failure. So it was important to build something really easy to help us get back on track. Here are some notes. We essentially followed this guide from Adafruit which links out to this guide for the CircuitPython part.

I read about aesthetic uses of Latin Squares on John Cook’s site a few months ago. Since I maintain a resource to use colour tables in Igor Pro, I thought it would be fun to use Latin Squares to display colour tables for easy visualisation. Briefly, I wrote some code to generate a 9 x 9 latin square and assigned the values 1 – 9 to a colour table wave. The results were nice.

I found this great puzzle hidden in an app aimed at children. Skip to the solution. If you want to work it out, don’t scroll down! Some blurb as a digression so that you don’t see the solution immediately The funny thing about this puzzle was that it was far too difficult for a child’s game.

A colleague said to me “Everyone is running on fumes with Easter being so late this year.” Really? Is it late? I admit to being completely perplexed by this religious date and its movement around the calendar. I always feel like I am the last to know when it is, let alone whether it is early or late. Let’s have a look at what constitutes an early or a late Easter. The data are available here. This is a quick post with no code example (sorry).

I run two pi-holes on my home network (details here). The older of the two was in need of a refresh. Here are some notes on how I did a reinstall. For those that don’t know, a pi-hole is a simple ad-blocking solution. You can donate to the project here. Problem The pi-hole itself can be easily updated over ssh using pihole -up however the OS also needs occasional updating for security.

A quick post about a puzzle called Wordle that is currently taking over the internet. It’s a mastermind-like game where the object is to guess an unknown 5-letter word. Puzzlers are encouraged to share their results after completing a puzzle. Here is an example for puzzle 192. So how do you know if your performance on today’s puzzle was any good? Why not benchmark your effort against the crowd?

This recent tweet made me chuckle. It does seem that many structural biology papers have a title that begins “The structural basis of…”. I took a quick PubMed survey to look at its popularity. First a search of "structural basis"[ti] AND "journal article"[pt] gives us the number of research papers with “structural basis” in the title. This plot of the number of papers with this title each year is levelling off.

As 2021 draws to a close, it’s time to check back in on a previous post. As a recap, Garmin Connect offered four challenges to run 3 x 505 km and 1 x 505 km, one in each of the four quarters of 2021. Completing all four would mean running 2021 km in 2021 . I used an R script to check my progress throughout the year (available here). Each quarter gave a set of results, the final set for the whole of 2021 is shown here.

In a previous post, I described a coding challenge sent to me by my colleague. Here is the challenge again: My solution was… let’s say… over-engineered. He did tell me that the winner (the challenge was set in an international coding competition) solved it in a ridiculously short time. He didn’t tell me how short which I think would have led me to take a different approach.