Re: How to query for Country Specific Data

An interesting question - should be a classic for Linked Data.
As I understand it, your primary problem for New Zealand is that there is no reliable information about the administrative geography.
It doesn't help for New Zealand (!), but for the UK you could use the Ordnance Survey's, which can be found in RDF via
http://osdir.com/ml/web.semantic.linking-open-data/2008-05/msg00011.html
We have made it linked data at os.rkbexplorer.com, with a SPARQL endpoint if you want it.
(If people are doing this sort of thing (if you thought of doing some of it yourself), then reusing the OS ontology might be a good idea.)

For the UK, it would be a case of jumping (follow-your-nose) backwards and forwards between the os and dbpedia, I suggest, using the os to find the inclusion and dbpedia to find the knowledge.
This afternoon I did a bunch of links between them (the bigger areas and towns), to let you have a go if you like, and these can be found at our os coreference service (crs) at
http://os.rkbexplorer.com/crs/

By the way, if you want an easy way of finding out what URIs might tell you what is known about a particular place (or anything), you could try our sameAs service at
http://www.rkbexplorer.com/sameAs/?uri=
So New Zealand would be
http://www.rkbexplorer.com/sameAs/?uri=http://dbpedia.org/resource/New_Zealand
And Wellington http://www.rkbexplorer.com/sameAs/?uri=http://dbpedia.org/resource/Wellington
and you can follow-your-nose from there.

Best
Hugh

On 24/05/2009 08:19, "richard.hancock@3kbo.com" <richard.hancock@3kbo.com> wrote:

Hi all,

I am wondering what are the best queries to run against the various LOD
datasets in order to get an idea of what Linked Data is currently
available for a specific country, e.g. New Zealand.

My plan was to start with Dbpedia and move out from there but so far my
Dbpedia queries so far haven't yielded the results I was hoping for.

My initial reasoning was that I could use the Dbpedia country URI ( i.e.
<http://dbpedia.org/resource/New_Zealand> ) as the beginning point for my
search and get a list of properties relating things to New Zealand using

SELECT DISTINCT ?p
FROM NAMED <http://dbpedia.org>
WHERE {
?s ?p <http://dbpedia.org/resource/New_Zealand> .
}

and a list of New Zealand properties using

SELECT DISTINCT ?p
FROM NAMED <http://dbpedia.org>
WHERE {
<http://dbpedia.org/resource/New_Zealand> ?p ?o  .
}

The first thing I looked for were properties that would let me find towns
and cities in New Zealand.

When I couldn't find obvious properties relating New Zealand towns and
cities to New Zealand I tried taking the URI of a specific city,
Wellington to see what properties linked it to New Zealand.

The query below shows that no property linked Wellington to New Zealand.

SELECT *
FROM NAMED <http://dbpedia.org>
WHERE {
 <http://dbpedia.org/resource/Wellington> ?p
<http://dbpedia.org/resource/New_Zealand> .
}

gives no results.

Going the other way showed that Wellington was the capital of New Zealand
but I was also expecting to see another property indicating that
Wellington was a city of New Zealand. I had hoped to find the second
property so that I could use it to find all other cities and towns within
New Zealand.

SELECT *
FROM NAMED <http://dbpedia.org>
WHERE {
 <http://dbpedia.org/resource/New_Zealand> ?p
<http://dbpedia.org/resource/Wellington>.
}

indicates that New_Zealand has a capital via
<http://dbpedia.org/property/capital> of Wellington

The best indication that Wellington is located in New Zealand was found
using the location property.

SELECT *
FROM NAMED <http://dbpedia.org>
WHERE {
<http://dbpedia.org/resource/Wellington>
<http://dbpedia.org/property/location> ?o .
}

gives the literal "Wellington, New Zealand"@en.

A scenario similar to the one between Wellington and New Zealand exists
between Berlin and Germany but here the literal value of the location
property proves less useful

SELECT ?location
FROM NAMED <http://dbpedia.org>
WHERE {
<http://dbpedia.org/resource/Berlin>
<http://dbpedia.org/property/location> ?location .
}

gives the literal "Berlin"@en

At this point I thought it was time to ask for help.

For the current Linked Data sets what is the best approach to take when
seeking to find what information has already been published for a specific
country ?

Depending on what you are looking for are some datasets better starting
points than others? E.g. for finding the towns and cities is geonames
(http://sws.geonames.org/) ,CIA Factbook or some other dataset, a better
starting point?

For Dbpedia are there plans to migrate properties like location
<http://dbpedia.org/property/location> which currently use literals to use
URIs instead?

Cheers,

Richard Hancock

Received on Sunday, 24 May 2009 19:07:31 UTC