Mastering Linked Data with Ptyhon @PyData Berlin 2014

In this talk, a general overview of the main features provided by the
rdflib package will be presented.
To this end, several code examples will be discussed regarding the DBPedia project, along with a case study concerning the analysis of a (semantic) social graph.

The case study will be focused on the integration between the
networkx (http://networkx.github.io) module and the rdflib library
in order to crawl, access (via SPARQL), and analyze a
Social Linked Data Graph represented using the FOAF (Friend of a Friend) schema (http://xmlns.com/foaf/0.1/).

Transcript

1. SEMANTIC WEB Mastering Linked Data with Python PYDATA B E R L I N Speaker Valerio Maggio valeriomaggio@gmail.com @leriomaggio +ValerioMaggio
2. This is me… …only half of me, btw… • I’m Valerio (Maggio) • Ph.D. in Computational Science • @University of Naples • PostDoc Researcher • @University of Salerno
3. (Big) Data Analysis Machine Learning Text Mining Natural Language Processing Software Maintenance Information Retrieval Linked Data & Semantic Web
4. PYDATA B E R L I N SEMANTIC
 Mastering Linked Data with Python WEB
5. WWW W O R L D W I D E W E B A BIG BOW TIE The Web Shape
6. WWW W O R L D W I D E W E B A BIG BOW TIE The Web Shape • SCC 
 (Core): • ~30% • Origin Region: • ~24% • Termination Region: • ~24% • Disconnecte d Pages • ~22%
7. THE WORLD WIDE WEB • WWW is full of data • Data published in different formats • e.g., PDF, TIFF, TXT • Linked to/by HTML pages (and other docs) • data that you can link to
8. LIMITATIONS • Data format is for human consumption • Specialized algos (and tools) to: • access, search, reuse data • This is when (and why) 
 Linked Data comes!
9. • Exploiting the basis of the WWW resource model: • URIs (Universal Resource Identifier): 
 Uniquely identify resources • Hyperlinks: Interconnect Resources LINKED D A T A Linked Data refers to a set of principles (and best practices) for publishing and connecting structured data on the Web using international standards of the W3C. . Doc6 Doc3 Doc1 Doc2 Doc4 Doc5
10. THE FIVE STARS PRINCIPLE: ★★★★★ ★: Data is available on the Web, in whatever format ★★: Data is available as machine-readable structured data ★★★: Data is available in a non-proprietary format ★★★★: Data is published using open data standards ★★★★★: All of the above apply, plus links to other data LINKED D A T A
11. LINKED D A T A EXAMPLES Textual Data Linked Data RDFa
12. BBC N A T U R E http://en.wikipedia.org/wiki/Python_(genus) http://dbpedia.org/page/Python_(genus) http://www.bbc.co.uk/nature/life/Python_(genus) http://rs.tdwg.org/dwc/terms/class “Reptile”
13. LINKED D A T A 2007
14. LINKED D A T A 2008
15. LINKED D A T A 2009
16. LINKED D A T A 2011
17. PYDATA B E R L I N SEMANTIC Mastering Linked Data with Python WEB
18. A SET OF PRINCIPLES SEMAN TIC W E B A system that enables machines to "understand" and respond to complex human requests based on their meaning. Tim Berners Lee A set of standards and best practices for sharing data and the semantics of that data over the Web for use by applications. Bob DuCharme
19. SEMAN TIC W E B STANDARD
 STACK
20. SEMAN TIC W E B STANDARD
 STACK
21. RESOURCE DESCRIPTION FRAMEWORK • RDF is not a data format • RDF: Data Model to express relationships between (arbitrary) data elements • RDF files can be serialized in multiple formats: • Turtle, N3, RDF/XML • Stored in Files & Databases (triple-store)
22. RDF DATA MODEL subject predicate object Set of Triples Graph-based model <subj1, pred1, obj1> <subj1, pred2, obj2> <subj2, pred1, obj1> <subj3, pred2, obj3> … Resources: subject is a Resource predicate is a Resource object is a Resource URIref(s) Identified by
23. BLANK NODES Anonymous nodes when you don’t know the URI of the thing you would like to reference blank node 1 “http://blog.johndoe.name” (_:ax1, "weblog", “http://blog.johndoe.name”)
 (_:ax1, "secondName", "Doe")
 (_:ax1, "firstName", "John")
 (_:ax1, "knows", _:zb7)
 (_:zb7, "secondName", "Taylor")
 (_:zb7, "firstName", "Steve")
 (_:zb7, "email", “stevetay@mail.com") weblog “John” secondName “Doe” knows blank node 2 firstName “stevetay@mail.com” email “Steve” secondName “Taylor” firstName Literal Values may optionally have: • language • type
24. SERIALIZATION FORMATS • N-Triples • N3 • RDF/XML • RDFa • RDF/JSON RDF allows for different serialisation formats • simple format - very readable • simple & compact • classic & original W3C Recommendation • compact & integrable within other formats • useful in case of RESTful APIs REUSE
25. EXAMPLE dbpedia.org/page/Python_(programming_language)
26. N-TRIPLES @prefix dbpedia-owl: <http://dbpedia.org/ontology/> . @prefix dbpedia: <http://dbpedia.org/resource/> . <http://dbpedia.org/resource/Python_(programming_language)> dbpedia-owl:designer dbpedia:Guido_van_Rossum. ! <http://dbpedia.org/resource/Python_(programming_language)> dbpedia-owl:developer dbpedia:Python_Software_Foundation. ! <http://dbpedia.org/resource/Python_(programming_language)> dbpedia-owl:influenced <http://dbpedia.org/resource/Go_(programming_language)>. ! <http://dbpedia.org/resource/Python_(programming_language)> dbpedia-owl:influenced <http://dbpedia.org/resource/Julia_(programming_language)>. ! <http://dbpedia.org/resource/Python_(programming_language)> dbpedia-owl:influenced http://dbpedia.org/resource/Ruby_(programming_language)>.
27. N-3 @prefix dbpedia-owl: <http://dbpedia.org/ontology/> . @prefix dbpedia: <http://dbpedia.org/resource/> . <http://dbpedia.org/resource/Python_(programming_language)> dbpedia-owl:designer dbpedia:Guido_van_Rossum; dbpedia-owl:developer dbpedia:Python_Software_Foundation; dbpedia-owl:influenced <http://dbpedia.org/resource/Go_(programming_language)>, <http://dbpedia.org/resource/Julia_(programming_language)>, <http://dbpedia.org/resource/Ruby_(programming_language)>.
28. RDF/XML
29. VOCABULARIES RDF V O C A B U L A R I E S (RDF) vocabulary is a defined set of predicates that can be used in an application. http://lov.okfn.org/dataset/lov/
30. LINKED RDF V O C A B U L A R I E S
31. SIMPLE PROTOCOL AND RDF QUERY LANGUAGE • SPARQL: standard query language for RDF Graphs • SPARQL attempts to match patterns in the graph • binds wildcard variables to find a solution
32. SPARQL EXAMPLES
33. PYDATA B E R L I N SEMANTIC
 Mastering Linked Data with Python WEB
34. TAMING THE SEMANTIC WEB RDFLIB P Y T H O N github.com/RDFLib
36. PERSISTENCE IN RDFLIB rdflib-sqlite rdflib-sqlalchemy rdflib-postgresql rdflib-mysql rdflib-sparqlstore rdflib-rdfjson rdflib-zodb rdflib-leveldb
37. PERSISTENCE IN RDFLIB rdflib-sqlite store load
38. RDFLIB & SPARQL
39. RDFLIB in action (Semantic) Social Network Analysis
40. THE D A T A FOAF w3.org/People/Berners-Lee/card#i foaf:knows dbpedia.org/resource/John_Markoff “Tim Berners-Lee” foaf:name foaf:Person
41. THE D A T A SKOS catalog:KnowledgeRepresentation skos:broader catalog:DescriptionLogic “Knoweldge Representation” skos:prefLabel skos:concept “Artificial Intelligence” skos:prefLabel skos:narrower catalog:ArtificialIntelligence “Artificial Intelligence” skos:prefLabel
42. THE D A T A SIOC ns:blogpost39 sioc:has_creator w3.org/People/Berners-Lee/card#i “title” sioc:title sioc:Post foaf:Person sioc:topic skos:Concept
43. SOCIAL NETWORK ANALYSIS • Who are the most connected people? • Who are the most influential people? • Where are the cliques? SNA R D F
44. LOAD & PARSE
45. BUILD SOCIAL GRAPH SPARQL Query
46. SOCIAL GRAPH ANALYSIS Find Cliques: vertices of a connected component Betweenness Centrality: the number of shortest paths from all vertices to all others that pass through that node.
47. EXTENDING THE NETWORK OF FRIENDS Leverage on
 SPARQL flexibility to look for new friends
48. INFERENCE
49. WHAT’S NEXT • OWL-RL: https://github.com/RDFLib/OWL-RL • FuXi Reasoner: https://github.com/RDFLib/FuXi • Python 3 Support keeps improving
50. SUGGESTED READINGS
51. THANKS FOR YOUR KIND ATTENTION valeriomaggio@gmail.com @leriomaggio +ValerioMaggio