/location /location /location – exploring Ordnance Survey Linked Data – Part 2
Ordnance Survey have now released an update to their linked data, which can be seen here. The new data now includes postcode information as well as a few changes to the administrative geography data. In this post I’ll go through what’s in the data, and give a few sample SPARQL queries.
I spoke a bit about the administrative geography data in a previous blog post – but the data has changed a bit since then. Just to re-cap the administrative geography linked data contains information about administrative and voting geographic regions. These include unitary authorities, counties, wards, constituencies, Welsh Assembly regions and a whole lot more [1]. Here are some examples:
If you want to find a full list of the sorts of thing you can find in the data simply go to the query interface (or SPARQL endpoint as it is know) and try the following query:
select distinct ?type
where { ?a a ?type . }
Now you have the list all of type of things in the data you can as for lists of instances of those types.
For example, the following query will return all of the unitary authorities:
select ?a
where {
?a a <http://data.ordnancesurvey.co.uk/ontology/admingeo/UnitaryAuthority> .
}
All of the names of all the regions have now been modelled using the SKOS vocabulary. If you want to find the official names of all the unitary authorities you can simple issue a query like:
select ?a ?name
where
{
?a a <http://data.ordnancesurvey.co.uk/ontology/admingeo/UnitaryAuthority> .
?a <http://www.w3.org/2004/02/skos/core#prefLabel> ?name .}
Also included in the data are two attributes called Unit ID and Area Code. These values are useful if you want to produce a mashup using this data and display it by boundary.
So for example, for Southampton (http://data.ordnancesurvey.co.uk/id/7000000000037256) the area code is UTA (for unitary authority) and the unit ID is 37256. These values can be used as follows:
/*here we set-up the our variable called ‘boundaryLayer’ with the strategies that we require. In this case, it is its ID and type i.e. Unitary Authority */
boundaryLayer = new OpenSpace.Layer.Boundary(“Boundaries”,
{ strategies: [new OpenSpace.Strategy.BBOX()], admin_unit_ids: [“37256”], area_code: [“UTA”] });
//then we add the bounadry to the map osMap.addLayer(boundaryLayer);
//this effectively refreshes the map, so that the boundary is visible
osMap.setCenter(osMap.getCenter());
to display the Southampton boundary using the OS OpenSpace API. See http://openspace.ordnancesurvey.co.uk/openspace/support.html for more details.
Arguably the most useful information in this data are the qualitative spatial relationships between different regions. Regions are related to the regions they contain, they are within and they touch. In the case of the touching relationship only regions of the same type have an explicit touching relationship. The exception to this are unitary authorities, counties, district and metropolitan district that also have touching relationships between each other. The following simple query will return a list of all counties, districts and unitary authorities that border The City of Southampton. It will also return their names:
PREFIX spatialrelations: <http://data.ordnancesurvey.co.uk/ontology/spatialrelations/>
select ?a ?name
where
{
?a spatialrelations:touches <http://data.ordnancesurvey.co.uk/id/7000000000037256> .
?a <http://www.w3.org/2004/02/skos/core#prefLabel> ?name .
}
If you are only interested in the bordering counties you can add an extra line to your query:
PREFIX spatialrelations: <http://data.ordnancesurvey.co.uk/ontology/spatialrelations/>
select ?a ?name
where
{
?a spatialrelations:touches <http://data.ordnancesurvey.co.uk/id/7000000000037256> .
?a <http://www.w3.org/2004/02/skos/core#prefLabel> ?name .
?a a <http://data.ordnancesurvey.co.uk/ontology/admingeo/County> .
}
Similarly, the following query returns all the county electoral divisions (and their names) within Hampshire:
PREFIX spatialrelations: <http://data.ordnancesurvey.co.uk/ontology/spatialrelations/>
select ?a ?name
where
{
?a spatialrelations:within <http://data.ordnancesurvey.co.uk/id/7000000000017765> .
?a <http://www.w3.org/2004/02/skos/core#prefLabel> ?name .
?a a <http://data.ordnancesurvey.co.uk/ontology/admingeo/CountyElectoralDivision> .
}
For convenience some shortcuts have been added to the data in this release. For certain nesting geographies, such as the county – district – parish or district – ward nestings, various new properties have been added. For example, the property ‘counyElectoralDivision‘ relates all counties to their constituent county electoral divisions. The above query can now be done in a simpler way:
PREFIX admingeo: <http://data.ordnancesurvey.co.uk/ontology/admingeo/>
select ?a ?name
where
{
<http://data.ordnancesurvey.co.uk/id/7000000000017765> admingeo:countyElectoralDivision ?a .
?a <http://www.w3.org/2004/02/skos/core#prefLabel> ?name .
}
Similar predicates such as ‘county‘, ‘district‘, ‘ward‘, ‘constituency‘ etc. provide similar shortcuts. For example, the following returns all the Westminster constituencies in South East England.
PREFIX admingeo: <http://data.ordnancesurvey.co.uk/ontology/admingeo/>
select ?a ?name
where {
<http://data.ordnancesurvey.co.uk/id/7000000000041421> admingeo:westminsterConstituency ?a .
?a <http://www.w3.org/2004/02/skos/core#prefLabel> ?name . }
The most significant introduction to this data is the inclusion of postcode information. The data now contains information about postcode units, postcode sectors, postcode districts and postcode areas. For each postcode unit an easting/northing coordinate value is given [2] along with the district, ward and county (where applicable) that contains said postcode unit. An example of this can be seen for the Ordnance Survey postcode SO16 4GU. Each postcode is also related to its containinb postcode area, sector and district.
The properties ‘ward‘, ‘district‘ and ‘county‘ relate a postcode to the relevant regions. The simple query:
PREFIX postcode: <http://data.ordnancesurvey.co.uk/ontology/postcode/>
select ?district
where {
<http://data.ordnancesurvey.co.uk/id/postcodeunit/SO164GU> postcode:district ?district .
}
returns the unitary authority that contains the postcode SO16 4GU.
This query:
PREFIX spatialrelations: <http://data.ordnancesurvey.co.uk/ontology/spatialrelations/>
select ?postcode
where
{
?postcode spatialrelations:within <http://data.ordnancesurvey.co.uk/id/postcodearea/SO> .
}
returns all the postcodes in the SO postcode area.
We can combine the above two queries to find the areas, along with their names, covered by the postcode area SO:
PREFIX spatialrelations: <http://data.ordnancesurvey.co.uk/ontology/spatialrelations/>
PREFIX postcode: <http://data.ordnancesurvey.co.uk/ontology/postcode/>
select distinct ?district ?name
where
{
?postcode spatialrelations:within <http://data.ordnancesurvey.co.uk/id/postcodearea/SO> .
?postcode postcode:district ?district .
?district <http://www.w3.org/2004/02/skos/core#prefLabel> ?name .
}
Hopefully these few examples will give you enough information to fully explore this new release of the Ordnance Survey linked data. For those of you who don’t like SPARQL watch this space – hopefully we will soon(ish) have an API built on top of this data to allow for even easy access.
[1] you’ll notice the ‘isDefinedBy’ link currently returns a 404 – not for long I hope 🙂
[2] lat/long to follow
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John's Weblog 
http://blog.ordnancesurvey.co.uk/2010/11/linked-data-at-ordnance-survey/
Just want to say that I’ve been trying to get a simple SPARQL query going, and your blog post is the first thing I’ve found that makes sense to me and gives me the tools I need to make my own queries. Really appreciated, thanks.