Visualize open data with Plone - eea.daviz PLOG 2013

Visualizing Open Data with Plone
a practical guide on how to query and visualize Linked Open Data
with eea.daviz product

Antonio De Marinis
Web Technology Management
European Environment Agency
www.eea.europa.eu

Linked Data evolution

2007

as per 2011
keeps growing...
> 1 million datasets
Watch video STRATA conference 2013

Open Data - what is it?

Open data is a philosophy and practice requiring
that certain data be freely available to everyone,
without restrictions from copyright, patents or
other mechanisms of control.

Linked Open Data (LOD) or simply Linked
Data is a technique to interlink all open datasets
into a web of data, aka semantic web, using
technologies like RDF and SPARQL.

SPARQL query structure

A SPARQL query comprises, in order:
● Prefix declarations, for abbreviating URIs
● Dataset definition, stating what RDF graph(s) are being queried
● A result clause, identifying what information to return from the query
● The query pattern, specifying what to query for in the underlying dataset
● Query modifiers, slicing, ordering, and otherwise rearranging query results
# prefix declarations
PREFIX foo: <http://example.com/resources/>
...
# dataset definition
FROM ...
# result
clause
SELECT ...
# query pattern
WHERE {
...
}
# query modifiers
ORDER BY ...

Real example querying DBpedia

SELECT * WHERE {
?subject rdf:type <http://dbpedia.org/ontology/City>.
?subject rdfs:label ?label.
?subject rdfs:comment ?abstract.
?subject <http://dbpedia.org/ontology/populationTotal> ?populationTotal.
FILTER (lang(?label) = "en" && lang(?abstract) = "en")
} LIMIT 5

Let's dive into a real example

SELECT * WHERE {
?subject rdf:type <http://dbpedia.org/ontology/City>.
?subject <http://dbpedia.org/ontology/populationTotal> ?populationTotal.
FILTER (lang(?label) = "en" && lang(?abstract) = "en" && (?populationTotal >= "5000000"^^xsd:
integer))
} LIMIT 5

Let's dive into a real example

PREFIX o: <http://dbpedia.org/ontology/>
PREFIX p: <http://dbpedia.org/property/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#>

SELECT DISTINCT * WHERE {
?subject a o:City.
OPTIONAL {?subject rdfs:comment ?abstract.}
?subject p:populationTotal ?populationTotal.
OPTIONAL {?subject geo:lat ?latitude.}
OPTIONAL {?subject geo:long ?longitude.}
FILTER (lang(?label) = "en" && lang(?abstract) = "en" && (?populationTotal >= "5000000"^^xsd:integer
&& ?populationTotal < "60000000"^^xsd:integer))
}
ORDER BY DESC(?populationTotal)

find all properties by exploring dbpedia e.g.
dbpedia http://dbpedia.org/page/Tokyo

Example without duplicates http://daviz.eionet.
europa.eu/data/local-sparql-queries/most-
populated-cities

Corresponding data visualisation with
Daviz

We have been able to create a data visualisation of
open linked data with filters/facets entirely through
the web in about 10 minutes!

live demo http://www.eea.europa.eu/sandbox/plog2013/most-populated-cities-
with-coordinates-plus

Removing redundancies
TIP: In order to get rid of some rednundancy you can use "SAMPLE" or "SELECT DISTINCT"


SELECT ?subject (sql:SAMPLE(?subject) as ?city)
(sql:SAMPLE(?label) as ?label)
(sql:SAMPLE(?latitude) as ?latitude)
live example http://daviz.eionet.europa.
(sql:SAMPLE(?longitude) as ?longitude)
max(?populationTotal) as ?maxPopulation
eu/visualisations/most-populated-cities
max(?rainyDays) as ?rainyDays

WHERE {
?subject a o:City.
OPTIONAL {?subject rdfs:comment ?abstract.}
?subject p:populationTotal ?populationTotal.
OPTIONAL {?subject geo:lat ?latitude.}
OPTIONAL {?subject geo:long ?longitude.}
OPTIONAL {?subject p:yearPrecipitationDays ?rainyDays.}
FILTER (lang(?label) = "en" && lang(?abstract) = "en" && (?populationTotal >= "5000000"^^xsd:integer))
}
GROUP BY ?subject
ORDER BY DESC(?maxPopulation)

More examples at Daviz show room
daviz.eionet.europa.eu

Example 2: Large companies (DBpedia)


SELECT * WHERE {
?subject rdf:type <http://dbpedia.org/ontology/Company>.
?subject p:numEmployees ?employees.
?subject o:location ?location.
?location geo:lat ?latitude.
?location geo:long ?longitude.
FILTER (lang(?label) = "en" && lang(?abstract) = "en" && ?employees > 10000)
}
ORDER BY DESC(?employees)
LIMIT 20

Example 3: Energy plants (Enipedia)

SPARQL Endpoint:http://enipedia.tudelft.nl/sparql

BASE <http://enipedia.tudelft.nl/wiki/>
PREFIX a: <http://enipedia.tudelft.nl/wiki/>
PREFIX prop: <http://enipedia.tudelft.nl/wiki/Property:>
PREFIX cat: <http://enipedia.tudelft.nl/wiki/Category:>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
select ?Name ?Point ?Generation_capacity where {
?powerPlant prop:Country a:Italy .
?powerPlant rdfs:label ?Name .
?powerPlant prop:Point ?Point .
?powerPlant prop:Generation_capacity_electrical_MW ?Generation_capacity .
}

More resources

● SPARQL endpoints and their status: http://labs.mondeca.
com/sparqlEndpointsStatus/index.html
● SPARQL tutorial by example: http://www.cambridgesemantics.com/semantic-
university/sparql-by-example
● eea.sparql package gives you a sparql client and data holder for plone
available on pypi
● eea.daviz bundle includes eea.sparql and the visualisations tools

Data table manipulation via drag and drop

EEA Daviz

And much more...

EEA Daviz

Live Demo

EEA Daviz - Resources

More live examples

○ Eionet
http://daviz.eionet.europa.eu

○ EEA
http://www.eea.europa.eu/data-and-maps/daviz

Visualize open data with Plone - eea.daviz PLOG 2013

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