Where are the Africa grid/tile maps?

First – before anyone writes in, it’s possible that there are Africa grid maps out there. But I haven’t seen any. And second, I’m not certain whether you’d call these grid maps, tile maps or both. For the purposes of this entry I’ll probably alternate between both terms.

Anyhow, last week I wanted to visualise malaria deaths in countries throughout Africa from 2000-2014 (once again, the brief was from the excellent #MakeoverMonday initiative – using publicly available data to practice our Tableau data visualisation skills). I wanted line charts to show deaths from 2000-2014, and small multiple charts to show the same thing for each country. The idea of a tile map came to mind as a perfect way to show small multiple line charts. I’ve seen tile maps for the US, and the UK, as well as more specialist maps for areas such as London or Scotland, but surprisingly not for anywhere else in the world. I thought a quick google would lead me to an example of an Africa tile map that I could beg, borrow or steal, but could find nothing.

Anyway – here is my effort – click the image to see the interactive version.

Dashboard 1-25

This immediately leads to an obvious second question (this blog is full of them). Why have you done it in French? I’ll answer that later.

There are several advantages and several disadvantages to a tile map. I feel here that I should reach for my textbooks on the shelf behind me to help me here, to see what experts Andy Kirk, Alberto Cairo and others suggest. Or to raid my favourites/bookmarks to get advice on the pros and cons of small multiple tile maps from data visualisation experts I follow. However I want to answer this my own way to make sure I understand the pros and cons unprompted.

My thoughts on some of the pros:

–  They are a great way of showing every country/state with equal prominence
–  They allow results from different states/countries to be compared visually, assuming that all scales/charts are consistent
–  Small multiples allow you to show a lot of individual data simultaneously / side-by-side
–  Because all information is shown, little need for interactivity (my version has more info on hovering in tooltips, but no further interactivity)
–  They are visually striking – it’s fun for the eyes to see all countries/states equally shaped and sized, with the overall country/continent retaining its shape as closely as possible

And some of the cons:

–  They are not geographically accurate. My map has Algeria and Lesotho in approximately the right place, but they are patently not the same size in reality
–  They are not the right chart for everything. If you don’t have something easily compared across every tile there’s little point
–  They are not to everyone’s taste – they are a “distortion” chart type after all

With this in mind, when I produced this experimental visualisation (in English), the number of likes and retweets on twitter was much higher than usual. Now, this isn’t the be-all and end-all, but it shows me that the combined advantages of something visually appealing, fun, and not seen before is an over-riding factor that trumps other considerations.

If I’m honest, this may not be a perfect example for a grid/tile map, but I wanted to try it and I’m pleased with the result. In terms of design and technical execution, I followed the method used by Brittany Fong here: http://www.bfongdata.com/2015/11/periodic-table-map.html.


She calls it a “periodic table” map and it’s easy to see why. Key is to assign each country a row and column number, just like has been done with the US states, and the visualisation should fall into place. The fun bit is using an atlas and graph paper (or in this day and age, the digital equivalent: dual-screen, a bitmap and Excel) to get those squares as close to an Africa map shape as possible.

In the US, there are small states in the East and large states in the midwest and west. In the UK there are far more populous consistencies in the south east than there are in rural Wales or Scotland. So I had to accept there would be a bit of spatial exaggeration given the large number of smaller countries in the west of the continent. In the end, mission hopefully accomplished.

In this case, there are large discrepancies between the malaria figures in the endemic and non-endemic countries, with the countries with most malaria cases very much forming a central belt of the continent. With geography being key, we potentially lose this accuracy by showing each country’s casualties in a grid map. I also made the decision to show logarithmic scales. Without this, only the countries with larges figures show with any prominence. Logarithmic scales allow countries with smaller figures to be shown more clearly at a small scale, however it makes comparison between countries more difficult. Showing the figures logarithmically goes slightly against the grain, but it’s important to state this on the visualisation to make it clear.

And why French? Well, here is a page from the latest print version, out today, of a weekly French newspaper/magazine Courrier International:


Look familiar? Just a colour change, some wording and a biography and it’s my viz out there for the world (well, mostly France) to see! It certainly works well as a static dativiz, with my original interactive version (further up in this post) still available and complementing it.

So it seems that whether you call them tile maps or grid maps they are certainly popular.

I’m on a roll now – next stop the departments of France (work in progress below – here’s a static version). This time, the y-axis is the percentage of people aged 75+ in every department, so every tile is much more comparable. Departments are slightly smaller and more crowded around Paris, but otherwise quite consistent in size, so this particular tile map (also new, according to my googling skills, if nothing else) works quite nicely.

Dashboard 1-26

Time to check the atlas for more!

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