Over the holidays, I had an idea about looping an animation between two images. I wrote some code to do this in Igor Pro (sorry, no R this time…). This post describes how the code works and how you can make a similar animation. There was a reason to do this animation, but as a proof of principle I used two band logos.

Quaternions are essentially magic. With just four numbers, they can describe the position and orientation of an object in space. For example, the rotation of an object about one axis. Consecutive rotations can also be described by a quaternion.

A while back I visited Artistes & Robots in Paris. Part of the exhibition was on the origins of computer-based art. Nowadays this is referred to as generative art , where computers generate artwork according to rules specified by the programmer.

I was recently reminded of the wonders of paulstretch by a 8-fold slowed down version of Pyramid Song by Radiohead. Paulstretch is an audio manipulation widget that can stretch or compress the time of an audio recording. Note that it doesn’t “slow down” or “speed up” a recording, it resamples the audio and recasts it over a different time scale while maintaining the pitch.

Garmin Connect has a number of plots built in, but to take a deeper dive into all your fitness data, you need to export a CSV and fire up R. This post is a quick guide to some possibilities for running data.  There’s a few things that I wanted to look at. For example, how does my speed change through the year? How does that compare to previous years? If I see some trends, is that the same for short runs and long runs?

Our lab is international. People born all over the world have come to work in my group. I’m proud of this fact, especially in the current political climate. I’ve previously used the GoogleMaps API to display a heat map on our lab webpage. It shows where in the world people in the lab come from. This was OK, but I wanted to get an R based solution to make this graphic to make it easier to automate updates.

This is a quick “how to” post. There is a licensed version of PyMol (MacPyMol) available, but the open source version can be installed on a Mac free of charge. The official page has a guide, which is not terribly detailed, and I found this excellent guide which is unfortunately out-of-date.

A long time ago I posted a little Automator routine to convert Word doc/docx files to PDF. Not long after that, this routine ceased to work due to changes in Microsoft Word (I think). It’s still very useful to convert a whole folder of docx files to PDF in order to avoid Word and just use Preview on the Mac. For committee work or for marking students’ work, I often have a whole folder of docx files and would prefer it if they were in PDF format.

I’d seen the small multiple artwork of running and cycling routes from Marcus Volz’s R package Strava all over the web. Ads for “posters of your GPS tracks” pop up on Reddit and I’d notice a few #Rstats people put up their posters on Twitter. I’ve had the package bookmarked for a while and this week I finally got round to generating a small multiple poster of some of my cycling routes.

This deserved a bit of further explanation, due to the stupidity involved. My code was giving an unexpected result and I was having a hard time figuring out the problem. The unexpected result was that a resampled set of 2D coordinates were not being rotated randomly. I was fortunate to be able to see this otherwise I would have never found this bug and probably would’ve propagated the error to other code projects.