.. _gettingstarted:
===============================
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``:
.. code-block :: bash
$ 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
:class:`~rdflib.graph.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. :meth:`~rdflib.Graph.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:
.. code-block:: text
[
(subject, predicate, object),
(subject1, predicate1, object1),
...
(subjectN, predicateN, objectN)
]
A tiny usage example:
.. code-block:: python
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:
.. code-block:: python
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 :doc:`examples ` can be found in the :file:`examples` folder in the source distribution.