Getting started with RDFLib

Installation

RDFLib is open source and is maintained in a GitHub repository. RDFLib releases, current and previous are listed on PyPi

The best way to install RDFLib is to use easy_install or pip:

$ easy_install rdflib

Support is available through the rdflib-dev group:

http://groups.google.com/group/rdflib-dev

and on the IRC channel #rdflib on the freenode.net server

The primary interface that RDFLib exposes for working with RDF is a Graph. The package uses various Python idioms that offer an appropriate way to introduce RDF to a Python programmer who hasn’t worked with RDF before.

RDFLib graphs are not sorted containers; they have ordinary set operations (e.g. add() to add a triple) plus methods that search triples and return them in arbitrary order.

RDFLib graphs also redefine certain built-in Python methods in order to behave in a predictable way; they emulate container types and are best thought of as a set of 3-item triples:

[
    (subject,  predicate,  object),
    (subject1, predicate1, object1),
    ...
    (subjectN, predicateN, objectN)
 ]

A tiny usage example:

import rdflib

g = rdflib.Graph()
result = g.parse("http://www.w3.org/People/Berners-Lee/card")

print("graph has %s statements." % len(g))
# prints graph has 79 statements.

for subj, pred, obj in g:
   if (subj, pred, obj) not in g:
       raise Exception("It better be!")

s = g.serialize(format='n3')

A more extensive example:

from rdflib import Graph, Literal, BNode, Namespace, RDF, URIRef
from rdflib.namespace import DC, FOAF

g = Graph()

# Create an identifier to use as the subject for Donna.
donna = BNode()

# Add triples using store's add method.
g.add( (donna, RDF.type, FOAF.Person) )
g.add( (donna, FOAF.nick, Literal("donna", lang="foo")) )
g.add( (donna, FOAF.name, Literal("Donna Fales")) )
g.add( (donna, FOAF.mbox, URIRef("mailto:donna@example.org")) )

# Iterate over triples in store and print them out.
print("--- printing raw triples ---")
for s, p, o in g:
    print((s, p, o))

# For each foaf:Person in the store print out its mbox property.
print("--- printing mboxes ---")
for person in g.subjects(RDF.type, FOAF.Person):
    for mbox in g.objects(person, FOAF.mbox):
        print(mbox)

# Bind a few prefix, namespace pairs for more readable output
g.bind("dc", DC)
g.bind("foaf", FOAF)

print( g.serialize(format='n3') )

Many more examples can be found in the examples folder in the source distribution.