Blog Posts by Andrew B. Collier / @datawookie

A contribution which I wrote for Antarctica and the Arctic Circle: A Geographic Encyclopedia of the Earth’s Polar Regions.

Following up on my previous post about generating Sankey plots with the riverplot package. It’s also possible to generate plots which have constant coloured edges.

A contribution which Claire and I wrote for Antarctica and the Arctic Circle: A Geographic Encyclopedia of the Earth’s Polar Regions.

I’ve updated my Comrades Marathon pacing chart to include both the Up and Down runs. You can grab it here. The data for this year’s race are not yet finalised (I think we will be running 87 km), but you can make changes when it’s all confirmed.

The cost of fuel in South Africa (and I imagine pretty much everywhere else) is a contentious topic. It varies from month to month and, although it is clearly related to the price of crude oil and the exchange rate, various other forces play an influential role.

A contribution which I wrote for Antarctica and the Arctic Circle: A Geographic Encyclopedia of the Earth’s Polar Regions. As a side note, I am normally quite pedantic about “Earth” and “Sun” being capitalised but the editor of the Encyclopaedia evidently had different views on this point.

A contribution which Claire and I wrote for Antarctica and the Arctic Circle: A Geographic Encyclopedia of the Earth’s Polar Regions.

A contribution which I wrote for Antarctica and the Arctic Circle: A Geographic Encyclopedia of the Earth’s Polar Regions.

I have just been trying to import some data into R. The data were exported from a SQL Server client in tab-separated value (TSV) format. However, reading the data into R the “usual” way produced unexpected results:

The book Graph Databases by Ian Robinson, Jim Webber and Emil Eifrem gives an engaging overview of Graph Databases, describing typical use cases and illustrating the syntax used to construct and query them.

The book R for Business Analytics by Ajay Ohri sets out to look at “some of the most common tasks performed by business analysts and helps the user navigate the wealth of information in R and its 4000 packages.” In my opinion it succeeds in covering an extensive range of topics but fails to provide anything of substantial use to its intended audience. At least, not anything that could not be uncovered by a brief internet search.

I recently read an article (no longer available, unfortunately) which showed how to download Option Chain data from Google Finance using R.

Manfred Schroeder’s book Fractals, Chaos, Power Laws: Minutes from an Infinite Paradise is a fruitful source of interesting topics and projects. He gives a thorough description of Diffusion-Limited Aggregation (DLA) as a technique for simulating physical processes which produce intricate branching structures. Examples, as illustrated below, include Lichtenberg Figures, dielectric breakdown, electrodeposition and Hele-Shaw flow.

A few years ago I ordered a copy of the 2005 edition of Creating More Effective Graphs by Naomi Robbins. Somewhat shamefully I admit that the book got buried beneath a deluge of papers and other books and never received the attention it was due. Having recently discovered the R Graph Catalog, which implements many of the plots from the book using ggplot2, I had to dig it out and give it some serious attention.

Recently I was in my local Standard Bank branch. After finally reaching the front of the queue and being helped by a reasonably courteous young man, I was asked if I would mind filling out a survey. Sure. No problem. I had been in the bank for 30 minutes, I could probably afford another 30 seconds.

I have been looking for an intuitive way to plot flows or connections between states in a process. An obvious choice is a Sankey Plot, but I could not find a satisfactory implementation in R… until I read the post by January Weiner. His {riverplot} package does precisely what I am need.

In my previous post I gave some background information on the Commitments of Traders report along with a selection of summary plots.

A paper authored with my very talented student, Claire Antel, entitled “Investigating Dunedin whistlers using volcanic lightning” has just been published in Geophysical Research Letters. The paper looks at electromagnetic signals (“whistlers”) received at Dunedin, New Zealand, caused by lightning over volcanoes thousands of km away near the Aleutian Chain.

It has been suggested that the average Comrades Marathon runner is gradually getting older. As an “average runner” myself, I will not deny that I am personally getting older. But, what I really mean is that the average age of all runners taking part in this great event is gradually increasing. This is not just an idle hypothesis: it is supported by the data. If you’re interested in the technical details of the analysis, these are included at the end, otherwise read on for the results.