Friday, July 4, 2014

Optimizing your Coffee Fix

Canadians like their coffee. In fact, the average Canadian drinks 55% more coffee per day than the average American, and Canadians are ranked 9th in the world for overall coffee consumption. Because of this, it's hardly a surprise that coffee shops are literally all over the place in Canadian cities.

Pretend for a moment that you're out and about in Edmonton one day, and absolutely need your coffee fix. So badly, in fact, that you're only willing to travel the absolute shortest possible distance to your nearest Tim Hortons or Starbucks (Canada's two most popular coffee shop chains). If you made a map of the city based on where the nearest Tim Hortons is, it would look something like this:

Similarly, a map based on where the nearest Starbucks is would look like this:

(If your browser doesn't like Google maps, check out images of the maps for Tim Hortons and Starbucks. Please note that the maps are only as accurate as Google's knowledge of the world is.)

These are called Voronoi diagrams, which split up the city based on where the closest relevant coffee shop is. Each region corresponds to a single coffee shop, and everywhere within that region is closer to that coffee shop than any other.

It turns out that Edmonton has about one Tim Hortons for every 10,000 people, and about half as many Starbucks. Not too surprisingly, coffee chains tend to be clustered quite a bit downtown and near the U of A campus, leaving the industrial parks to the east rather desolate and missing out on a good brew. The extremely even distribution of Tim Hortons locations in Sherwood Park seems a bit too good to be true, though.

Apart from helping you out with your coffee purchasing optimization, Voronoi diagrams actually do have plenty of real uses. Diagrams like this were famously used in 1854 to show that residents who lived closest to one particular well were dying of cholera, which lead to the discovery that diseases can be spread by contaminating water.

In the case of coffee shops in Edmonton, they can be helpful in city planning or for businesses choosing where to establish new franchises. And, of course, if your caffeine priorities are straight, they can help you get the fastest fix.

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