I’ll just mention a data quality problem that’s annoyed me with DBpedia so far.

People often get confused if longitude is east or west,  so they get the sign 
wrong.  If you plot coordinates from Wikipedia you find a shadow image of 
Europe,  for instance,  reflected across the prime meridian.  It turns out,  
however,  there are a bunch of shipwrecks and seamounts out there too.

It would be nice to see these cleaned up.

From: Denny Vrandečić 
Sent: Thursday, January 17, 2013 10:13 AM
To: Discussion list for the Wikidata project. 
Subject: Re: [Wikidata-l] Coordinate datatype -- update

Nine decimals is what is used for WAAS reference stations, which appear in 
Wikipedia. 

<http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System#List_of_reference_stations>

I actually also think it is a bit excessive, but it is there and looks legit. 
I'd rather support it than not (and save 20 MB of disk space).

Some of the validations sound useful (no values greater than 360), others a bit 
restrictive (same number of decimal places). I'd prefer the software to be 
rather lax than draconic (it *is* a wiki, after all).
I agree about trailing zeros. They are covered by the precision parameter.

Thanks for the input!
Cheers,
Denny





2013/1/17 Andy Mabbett <[email protected]>

  On 17 January 2013 10:19, Denny Vrandečić <[email protected]> 
wrote:
  > If you have any further comments on the datatype for coordinates, say so
  > here.


  > 
<http://meta.wikimedia.org/wiki/Wikidata/Development/Representing_values#Coordinate>

  Nine decimal places seems excessive.

  We can apply some rudimentary validation: no latitude or longitude
  values greater than 360, for instance (perhaps other criteria
  dependent on the coordinate system); latitude and longitude should
  have the same number of decimal places; trailing zeroes are
  significant and must not be discarded.

  --
  Andy Mabbett
  @pigsonthewing
  http://pigsonthewing.org.uk


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