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Michele Pasin edited this page Apr 1, 2017 · 16 revisions

Welcome to Ontospy's documentation!

Ontospy is a lightweight Python library and command line tool for inspecting and visualizing vocabularies encoded in the RDF family of languages .

In a nutshell

Ontospy can be used either as an interactive command line interface (a repl) or as a Python package.

Calling the ontospy command from a terminal window launches a utility for scanning a knowledge model encoded in RDF (or any of its dialects e.g. RDFS, OWL or SKOS).

For example, if you pass a valid graph URI e.g.

ontospy http://purl.org/spar/frbr

Ontospy will attempt to extract and print out any ontology-related information contained in that graph.

Many other options are available, in particular Ontospy allows to load/save ontologies from/to a local repository so that they can be cached and quickly reloaded for inspection later on. All without leaving your terminal window!

OntospyVideo

Is Ontospy for me?

Here are some reasons why you should use it:

  • You are developing a Python application that needs to extract schema information from an RDF, SKOS or OWL vocabulary.
  • You have a bunch of RDF vocabularies you regularly need to interrogate, but do not want to load a full-blown ontology editor like Protege.
  • You need to quickly generate documentation for an ontology, either as simple html pages or via some more elaborate interactive visualization.
  • You love the command line and would never leave it no matter what.

note: Ontospy does not offer any ontology-editing features, nor it can be used to interrogate a triplestore.

Quick example

If used as a Python package, the basic workflow is the following: load a graph by instantiating the Ontospy class with a file containing RDFS, OWL or SKOS definitions; you get back an object that lets you interrogate the ontology. That's all!

Let's take a look at the Friend Of A Friend vocabulary.

In [1]: import ontospy
INFO:rdflib:RDFLib Version: 4.2.0

In [2]: model = ontospy.Ontospy("http://xmlns.com/foaf/0.1/")
----------
Loaded 631 triples from <http://xmlns.com/foaf/0.1/>
started scanning...
----------
Ontologies found...: 1
Classes found......: 14
Properties found...: 67
Annotation.........: 7
Datatype...........: 26
Object.............: 34
SKOS Concepts......: 0
----------

In [3]: model.classes
Out[3]:
[<Class *http://www.w3.org/2003/01/geo/wgs84_pos#SpatialThing*>,
 <Class *http://xmlns.com/foaf/0.1/Agent*>,
 <Class *http://xmlns.com/foaf/0.1/Document*>,
 <Class *http://xmlns.com/foaf/0.1/Group*>,
 <Class *http://xmlns.com/foaf/0.1/Image*>,
 <Class *http://xmlns.com/foaf/0.1/LabelProperty*>,
 <Class *http://xmlns.com/foaf/0.1/OnlineAccount*>,
 <Class *http://xmlns.com/foaf/0.1/OnlineChatAccount*>,
 <Class *http://xmlns.com/foaf/0.1/OnlineEcommerceAccount*>,
 <Class *http://xmlns.com/foaf/0.1/OnlineGamingAccount*>,
 <Class *http://xmlns.com/foaf/0.1/Organization*>,
 <Class *http://xmlns.com/foaf/0.1/Person*>,
 <Class *http://xmlns.com/foaf/0.1/PersonalProfileDocument*>,
 <Class *http://xmlns.com/foaf/0.1/Project*>]

In [4]: model.properties
Out[4]:
[<Property *http://xmlns.com/foaf/0.1/account*>,
 <Property *http://xmlns.com/foaf/0.1/accountName*>,
 <Property *http://xmlns.com/foaf/0.1/accountServiceHomepage*>,
 <Property *http://xmlns.com/foaf/0.1/age*>,
 <Property *http://xmlns.com/foaf/0.1/aimChatID*>,
 <Property *http://xmlns.com/foaf/0.1/based_near*>,
 <Property *http://xmlns.com/foaf/0.1/birthday*>,
 <Property *http://xmlns.com/foaf/0.1/currentProject*>,
 <Property *http://xmlns.com/foaf/0.1/depiction*>,
	### etc....
	]

In [5]: model.printClassTree()
[1]    http://www.w3.org/2003/01/geo/wgs84_pos#SpatialThing
[12]   ----_file_:Person
[2]    _file_:Agent
[4]    ----_file_:Group
[11]   ----_file_:Organization
[12]   ----_file_:Person
[3]    _file_:Document
[5]    ----_file_:Image
[13]   ----_file_:PersonalProfileDocument
[6]    _file_:LabelProperty
[7]    _file_:OnlineAccount
[8]    ----_file_:OnlineChatAccount
[9]    ----_file_:OnlineEcommerceAccount
[10]   ----_file_:OnlineGamingAccount
[14]   _file_:Project


In [6]: model.toplayer
Out[6]:
[<Class *http://www.w3.org/2003/01/geo/wgs84_pos#SpatialThing*>,
 <Class *http://xmlns.com/foaf/0.1/Agent*>,
 <Class *http://xmlns.com/foaf/0.1/Document*>,
 <Class *http://xmlns.com/foaf/0.1/LabelProperty*>,
 <Class *http://xmlns.com/foaf/0.1/OnlineAccount*>,
 <Class *http://xmlns.com/foaf/0.1/Project*>]

In [7]: model.getClass("document")
Out[7]:
[<Class *http://xmlns.com/foaf/0.1/Document*>,
 <Class *http://xmlns.com/foaf/0.1/PersonalProfileDocument*>]

In [8]: a_class = _[0]

In [9]: print(a_class.serialize())
@prefix ns1: <http://www.w3.org/2002/07/owl#> .
@prefix ns2: <http://www.w3.org/2003/06/sw-vocab-status/ns#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://xmlns.com/foaf/0.1/Document> a rdfs:Class,
        ns1:Class ;
    rdfs:label "Document" ;
    rdfs:comment "A document." ;
    rdfs:isDefinedBy <http://xmlns.com/foaf/0.1/> ;
    ns1:disjointWith <http://xmlns.com/foaf/0.1/Organization>,
        <http://xmlns.com/foaf/0.1/Project> ;
    ns1:equivalentClass <http://schema.org/CreativeWork> ;
    ns2:term_status "stable" .



In [10]: a_class.parents()
Out[10]: []

In [11]: a_class.children()
Out[11]:
[<Class *http://xmlns.com/foaf/0.1/Image*>,
 <Class *http://xmlns.com/foaf/0.1/PersonalProfileDocument*>]

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