7
$\begingroup$

I'm probably misunderstanding something, but:

temp = CountryData["World", "FullPolygon"][[1,1,15737]]

(* note: FullForm shows these numbers aren't exactly identical, just very close *)

{{2.08158, 109.645}, {2.08158, 109.645}, {2.08158, 109.645}}

GeoArea[Polygon[GeoPosition[temp]]]

0.0000444087 meters squared

As nearly as I can tell, Mathematica is listing an island that's less than 1 cm^2, which is probably an error. Notes:

  • CountryData["World", "FullPolygon"] is a one element list that itself contains only a one-element list, so it's not like I'm going too deep.

  • Of the 24967 polygons total, 8173 are less than 1 km^2 in size, and 248 are less than 100 m^2 (the size of a small room).

This sort of thing is particularly annoying given Area of countries given by GeoBoundaries does not equal area in database where I show the total land area of Mathematica's polygons is only about 92% of the actual land area. (this mystery was solved later, see linked question for details)

Am I missing something or is this just bad data?

EDIT: I just tried using Entity["Country", "World"]["Polygon"], which has only 1851 polygons (there is no "FullPolygon" property) and is supposedly more up-to-date. However, this data also has several small islands, and the 559th entry in the list is the same island as above.

$\endgroup$
  • 4
    $\begingroup$ Is it in the Bikini Islands? That might explain things. $\endgroup$ – Daniel Lichtblau Jul 27 '18 at 2:04
  • 2
    $\begingroup$ @DanielLichtblau I actually checked before posting, in the hope of making an even sillier title, but no -- it's off the coast of Indonesia, close to the real Merundung Island, and only a few hundred feet from the Malaysia-Indonesia border. $\endgroup$ – barrycarter Jul 27 '18 at 2:28
  • $\begingroup$ That's just...wrong. Can we make it an honorary Bikini Island? (Maybe that would have political ramifications though...) $\endgroup$ – Daniel Lichtblau Jul 27 '18 at 2:33
  • $\begingroup$ @DanielLichtblau It turns out the next two smallest ones are also very close to political boundaries. Someone should look through the smallest ones and see if any are in the right region. Either that or connect the dots to see if they spell out a very rude word $\endgroup$ – barrycarter Jul 27 '18 at 2:37
  • 2
    $\begingroup$ Is this it? $\endgroup$ – user1066 Jul 28 '18 at 16:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.