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 <andy@pigsonthewing.org.uk>

On 17 January 2013 10:19, Denny Vrandečić <denny.vrandecic@wikimedia.de> 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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