Friday, 24 February 2017

Alternative maps

Don't get me wrong. I don't read defense magazines. The extracts below are from the Radio User magazine, that I used to get both from a professional interest in maritime and aero communications and a hobby interest in shortwave and medium wave listening ( DX-ing). It is an excellent source of information on ADS-B and AIS as well as general search and rescue and safety comms, and of course long distance broadcasting and propagation conditions.

It does however also cater for plane spotters and scanner enthusiast following military exercises, hence the 'alternative' map of Scandinavia below. The description of the made up fringe country between Norway and Iceland is hilarious, any similarities to Brexit island are purely coincidental

The challenge as always of course is how to re-make the map in Tableau. To make my life easier I'm ignoring the made up internal borders inside Sweden and Finland, and focusing on relocating New Zealand to the North Atlantic.

Lets start with a dataset listing the necessary countries. Tableau is very good at mapping them in their usual locations.

But how do we move New Zealand? Let's have a go extracting the generated coordinates and fiddling with the numbers. We select the countries on the map, view the data and it's a rare case that the summary has more info (generated coordinates) than the full data. Select everything and copy into the csv creator of choise, any spreadsheet application will do.

Now move New Zealand to its 'alternative' position, lets say 60N 5W, remove the (generated) from the header, save the csv and re-import into Tableau.If you put the new coordinates on X and Y you get dots at the right places. But change to a filled map and New Zealand stubbornly refuses to move from the Pacific to the Atlantic.

Ok so clearly Tableau is doing things behind the scenes. Of course it has to as we haven't specified the relative size of the countries. Let's do that by adding the area of each country in another column. So can we escape by setting the geographic role to 'None'? 

It has flattened Norway, so it is sort of re-projecting the shape from Mercator projection. But everything is in the wrong place, and we've pushed the size as far up as possible. Bear in mind that we have another weapon in our disposal, zooming. Tableau doesn't zoom into the marks at the same magnification levels that it zooms into a map. You can see this by zooming into my Makeover Sunday II map. In this case, we want to zoom out to see if it gels the countries together. 

So it's not that simple. At this point we give up and leave it for another day.

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