rdflib-hdt 3.0

PyPi安装（推荐）

# you can install using pip
pip install rdflib_hdt

# or you can use pipenv
pipenv install rdflib_hdt

手动安装

要求：pipenv

图形使用（推荐）

fromrdflibimportGraphfromrdflib_hdtimportHDTStorefromrdflib.namespaceimportFOAF# Load an HDT file. Missing indexes are generated automatically# You can provide the index file by putting them in the same directory than the HDT file.store=HDTGraph("test.hdt")# Display some metadata about the HDT document itselfprint(f"Number of RDF triples: {len(store)}")print(f"Number of subjects: {store.nb_subjects}")print(f"Number of predicates: {store.nb_predicates}")print(f"Number of objects: {store.nb_objects}")print(f"Number of shared subject-object: {store.nb_shared}")

使用rdflibapi，还可以在HDT文档上execute SPARQL queries。 如果您这样做，我们建议您首先调用optimize_sparql函数，这样可以优化 HDT文档上下文中的rdflibsparql查询引擎。在

fromrdflibimportGraphfromrdflib_hdtimportHDTStore,optimize_sparql# Calling this function optimizes the RDFlib SPARQL engine for HDT documentsoptimize_sparql()graph=Graph(store=HDTStore("test.hdt"))# You can execute SPARQL queries using the regular RDFlib APIqres=graph.query("""
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?friend WHERE {
   ?a foaf:knows ?b.
   ?a foaf:name ?name.
   ?b foaf:name ?friend.
}""")forrowinqres:print(f"{row.name} knows {row.friend}")

HDT文档使用

fromrdflib_hdtimportHDTDocument# Load an HDT file. Missing indexes are generated automatically.# You can provide the index file by putting them in the same directory than the HDT file.document=HDTDocument("test.hdt")# Display some metadata about the HDT document itselfprint(f"Number of RDF triples: {document.total_triples}")print(f"Number of subjects: {document.nb_subjects}")print(f"Number of predicates: {document.nb_predicates}")print(f"Number of objects: {document.nb_objects}")print(f"Number of shared subject-object: {document.nb_shared}")# Fetch all triples that matches { ?s foaf:name ?o }# Use None to indicates variablestriples,cardinality=document.search_triples((None,FOAF("name"),None))print(f"Cardinality of (?s foaf:name ?o): {cardinality}")fors,p,ointriples:print(triple)# The search also support limit and offsettriples,cardinality=document.search_triples((None,FOAF("name"),None),limit=10,offset=100)# etc ...

HDT文档还支持在一组三元组模式上评估连接。在

fromrdflib_hdtimportHDTDocumentfromrdflibimportVariablefromrdflib.namespaceimportFOAF,RDFdocument=HDTDocument("test.hdt")# find the names of two entities that know each othertp_a=(Variable("a"),FOAF("knows"),Variable("b"))tp_b=(Variable("a"),FOAF("name"),Variable("name"))tp_c=(Variable("b"),FOAF("name"),Variable("friend"))query=set([tp_a,tp_b,tp_c])iterator=document.search_join(query)print(f"Estimated join cardinality: {len(iterator)}")# Join results are produced as ResultRow, like in the RDFlib SPARQL APIforrowiniterator:print(f"{row.name} knows {row.friend}")