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Ordnance survey Linked Data – Simple SPARQL example

August 1, 2013 Leave a comment

Yesterday I received a request asking how to extract some simple data from the Ordnance Survey linked data using a SPARQL query. This post is not intended as a SPARQL tutorial – you can find plenty of those here.

A user wanted to know how to retrieve the name, unit-id, GSS Code, lat and long of all the unitary authorities, districts and metropolitan districts in England, Scotland and Wales as a CSV file.

To extract this information for all of the districts go to the Ordnance Survey’s Boundary-Line(TM) linked data SPARQL endpoint explorer and in the response format drop down menu select CSV. Now in the query window enter the following query:

select ?name ?lat ?long ?gss ?unit_id

where

{

?x <http://www.w3.org/2000/01/rdf-schema#label> ?name .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#lat> ?lat .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?long .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/gssCode> ?gss .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/hasUnitID> ?unit_id .

?x a <http://data.ordnancesurvey.co.uk/ontology/admingeo/District> .

}

This query selects the various attributes from the data, and the final line of the query makes sure that all of the entities selected from the data are of type District.

Scroll down the page and you should see the query response. To get the values for the district, unitary authorities and metropolitan districts we need to use a SPARQL union to gather together all of the results as follows:

select ?name ?lat ?long ?gss ?unit_id

where

{

{

?x <http://www.w3.org/2000/01/rdf-schema#label> ?name .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#lat> ?lat .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?long .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/gssCode> ?gss .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/hasUnitID> ?unit_id .

?x a <http://data.ordnancesurvey.co.uk/ontology/admingeo/District> .

}

UNION

{

?x <http://www.w3.org/2000/01/rdf-schema#label> ?name .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#lat> ?lat .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?long .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/gssCode> ?gss .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/hasUnitID> ?unit_id .

?x a <http://data.ordnancesurvey.co.uk/ontology/admingeo/MetropolitanDistrict> .

}

UNION

{

?x <http://www.w3.org/2000/01/rdf-schema#label> ?name .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#lat> ?lat .

?x <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?long .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/gssCode> ?gss .

?x <http://data.ordnancesurvey.co.uk/ontology/admingeo/hasUnitID> ?unit_id .

?x a <http://data.ordnancesurvey.co.uk/ontology/admingeo/UnitaryAuthority> .

}

}

order by ?name

The ‘order by’ at the end of the query orders the results in alphabetical order.

To save the query results as a CSV file again make sure that response format in set to CSV and this time, before hitting the query button, make sure the ‘show raw response’ option is selected. Now hit the query button and you should be given the option to save your query result as a CSV file.

Ordnance Survey Linked Data and the Reconciliation API

April 25, 2013 5 comments

The new Ordnance Survey Linked Data has a reconciliation API that allows users to turn text into URIs by matching against the Ordnance Survey linked data using a tool called open refine.

I’m not an expert on open refine but had a quick try of the tool today using some open data about libraries (available here). Instructions on installing Open Refine can be found here.

To use the Open Refine load your data into the tool and create your new project. On loading the library data into Open Refine you should see something like this:

Image

We can use Open Refine to turn the labels in both the ‘county’ column and postcode column into URIs. For the county column click the down arrow next the column name and select reconcile -> start reconciling. Now click ‘Add Standard Service’ and add the following URL http://data.ordnancesurvey.co.uk/datasets/boundary-line/apis/reconciliation. 

As the ‘county’ column will contain a mixture of types select the ‘reconcile against no particular type’ option and click ‘start reconciling’. You should now see that most of the text labels have turned to hyperlinks (note OS linked data does not included Northern Ireland data…this accounts for the missing values).

You can do the same for the postcode column, but this time use the API at: http://data.ordnancesurvey.co.uk/datasets/code-point-open/apis/reconciliation

Your data should now look something like:

Image

You have now successfully replaced the text in these columns with links to the OS linked data.

Another useful thing to try is a simple bit of geocoding based on postcodes. Again go to the postcode column and select “Edit Column -> Add Column by fetching URLs’. Where asked type in a column name (e.g. PC JSON) and in the Expression box type:

http://data.ordnancesurvey.co.uk/datasets/code-point-open/apis/search?output=json&query=’ + escape(value,’url’)

You should now see a column appear full of JSON results:

Screen Shot 2013-04-25 at 15.23.11

On the PC JSON column select “Edit Column -> Add Column Based on this column”. Again add a column name of your choice. I wanted to extract the value of the easting and northing and add it as a column so I called my new column ‘easting,northing’. In the expression box enter the following to get the value of the easting and northing:

with(value.parseJson(), pair, pair.results[0].easting + ‘,’ + pair.results[0].northing)

and you should now see something like:

Screen Shot 2013-04-25 at 15.27.27

Congratulations…you have now geo-coded your libary spreadsheet via a postcode and the OS linked data.

For more info on how to use Open Refine for reconciliation watch this youtube video.

Making things with Ordnance Survey Linked Data…

November 3, 2011 7 comments

Following the example of “Making things with BBC data” I thought I’d ask the same question for Ordnance Survey linked data. Please leave a comment if you’ve used Ordnance Survey linked data for anything from a quick hack, full blown project or if you even just link to it in your data. Thanks!

 

 

/location /location /location – exploring Ordnance Survey Linked Data – Part 2

October 25, 2010 5 comments

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&gt; .

}

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&gt; ?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/&gt;

select ?a ?name

where

{

?a spatialrelations:touches <http://data.ordnancesurvey.co.uk/id/7000000000037256&gt; .

?a <http://www.w3.org/2004/02/skos/core#prefLabel&gt; ?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/&gt;

select ?a ?name

where

{

?a spatialrelations:touches <http://data.ordnancesurvey.co.uk/id/7000000000037256&gt; .

?a <http://www.w3.org/2004/02/skos/core#prefLabel&gt; ?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/&gt;

select ?a ?name

where

{

?a spatialrelations:within <http://data.ordnancesurvey.co.uk/id/7000000000017765&gt; .

?a <http://www.w3.org/2004/02/skos/core#prefLabel&gt; ?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/&gt;

select ?a ?name

where

{

<http://data.ordnancesurvey.co.uk/id/7000000000017765&gt; admingeo:countyElectoralDivision ?a .

?a <http://www.w3.org/2004/02/skos/core#prefLabel&gt; ?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/&gt;

select ?a ?name

where {

<http://data.ordnancesurvey.co.uk/id/7000000000041421&gt; admingeo:westminsterConstituency ?a .

?a <http://www.w3.org/2004/02/skos/core#prefLabel&gt; ?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/&gt;

select ?district

where {

<http://data.ordnancesurvey.co.uk/id/postcodeunit/SO164GU&gt; postcode:district ?district .

}

returns the unitary authority that contains the postcode SO16 4GU.

This query:

PREFIX spatialrelations: <http://data.ordnancesurvey.co.uk/ontology/spatialrelations/&gt;

select ?postcode

where

{

?postcode spatialrelations:within <http://data.ordnancesurvey.co.uk/id/postcodearea/SO&gt; .

}

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/&gt;

PREFIX postcode: <http://data.ordnancesurvey.co.uk/ontology/postcode/&gt;

select distinct ?district ?name

where

{

?postcode spatialrelations:within <http://data.ordnancesurvey.co.uk/id/postcodearea/SO&gt; .

?postcode postcode:district ?district .

?district <http://www.w3.org/2004/02/skos/core#prefLabel&gt; ?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