我想在rdflib中定义我自己的名称空间“ http://example.org/”，但是显然不能这样做。无法弄清楚什么是正确的方法...
In [1]: import rdflib
INFO:rdflib:RDFLib Version: 4.2.2
In [2]: g = rdflib.Graph()
In [3]: from rdflib import Namespace
In [4]: n1 = Namespace("http://example.org/")
In [5]: u1 = n1['1']
In [6]: u1
Out[6]: rdflib.term.URIRef(u'http://example.org/1')
In [7]: g.bind('ex', n1)
In [8]: g.add((u1, u1, u1)
...: )
In [9]: g.serialize()
---------------------------------------------------------------------------
Exception Traceback (most recent call last)
<ipython-input-9-25a09aa9a7b5> in <module>()
----> 1 g.serialize()
/usr/local/lib/python2.7/site-packages/rdflib/graph.pyc in serialize(self, destination, format, base, encoding, **args)
937 if destination is None:
938 stream = BytesIO()
--> 939 serializer.serialize(stream, base=base, encoding=encoding, **args)
940 return stream.getvalue()
941 if hasattr(destination, "write"):
/usr/local/lib/python2.7/site-packages/rdflib/plugins/serializers/rdfxml.pyc in serialize(self, stream, base, encoding, **args)
64 # assert(
65 # namespaces["http://www.w3.org/1999/02/22-rdf-syntax-ns#"]=='rdf')
---> 66 bindings = list(self.__bindings())
67 bindings.sort()
68
/usr/local/lib/python2.7/site-packages/rdflib/plugins/serializers/rdfxml.pyc in __bindings(self)
31
32 for predicate in set(store.predicates()):
---> 33 prefix, namespace, name = nm.compute_qname(predicate)
34 bindings[prefix] = URIRef(namespace)
35
/usr/local/lib/python2.7/site-packages/rdflib/namespace.pyc in compute_qname(self, uri, generate)
328
329 if not uri in self.__cache:
--> 330 namespace, name = split_uri(uri)
331 namespace = URIRef(namespace)
332 prefix = self.store.prefix(namespace)
/usr/local/lib/python2.7/site-packages/rdflib/namespace.pyc in split_uri(uri)
500 return (ns, ln)
501 break
--> 502 raise Exception("Can't split '%s'" % uri)
Exception: Can't split 'http://example.org/1'