访问rdf列表成员的最佳方法是什么？我正在使用rdflib(python),但在普通的SPARQL中给出的答案也可以(这种类型的答案可以通过rdfextras,一个rdflib帮助程序库使用).
我正在尝试访问由Zotero生成的rdf中的特定期刊文章的作者(为简洁起见,已删除了一些字段)：
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:z="http://www.zotero.org/namespaces/export#"
xmlns:dcterms="http://purl.org/dc/terms/"
xmlns:bib="http://purl.org/net/biblio#"
xmlns:foaf="http://xmlns.com/foaf/0.1/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:prism="http://prismstandard.org/namespaces/1.2/basic/"
xmlns:link="http://purl.org/rss/1.0/modules/link/">
<bib:Article rdf:about="http://www.ncbi.nlm.nih.gov/pubmed/18273724">
<z:itemType>journalArticle</z:itemType>
<dcterms:isPartOf rdf:resource="urn:issn:0954-6634"/>
<bib:authors>
<rdf:Seq>
<rdf:li>
<foaf:Person>
<foaf:surname>Lee</foaf:surname>
<foaf:givenname>Hyoun Seung</foaf:givenname>
</foaf:Person>
</rdf:li>
<rdf:li>
<foaf:Person>
<foaf:surname>Lee</foaf:surname>
<foaf:givenname>Jong Hee</foaf:givenname>
</foaf:Person>
</rdf:li>
<rdf:li>
<foaf:Person>
<foaf:surname>Ahn</foaf:surname>
<foaf:givenname>Gun Young</foaf:givenname>
</foaf:Person>
</rdf:li>
<rdf:li>
<foaf:Person>
<foaf:surname>Lee</foaf:surname>
<foaf:givenname>Dong Hun</foaf:givenname>
</foaf:Person>
</rdf:li>
<rdf:li>
<foaf:Person>
<foaf:surname>Shin</foaf:surname>
<foaf:givenname>Jung Won</foaf:givenname>
</foaf:Person>
</rdf:li>
<rdf:li>
<foaf:Person>
<foaf:surname>Kim</foaf:surname>
<foaf:givenname>Dong Hyun</foaf:givenname>
</foaf:Person>
</rdf:li>
<rdf:li>
<foaf:Person>
<foaf:surname>Chung</foaf:surname>
<foaf:givenname>Jin Ho</foaf:givenname>
</foaf:Person>
</rdf:li>
</rdf:Seq>
</bib:authors>
<dc:title>Fractional photothermolysis for the treatment of acne scars: a report of 27 Korean patients</dc:title>
<dcterms:abstract>OBJECTIVES: Atrophic post-acne scarring remains a therapeutically challe *CUT*, erythema and edema. CONCLUSIONS: The 1550-nm erbium-doped FP is associated with significant patient-reported improvement in the appearance of acne scars, with minimal downtime.</dcterms:abstract>
<bib:pages>45-49</bib:pages>
<dc:date>2008</dc:date>
<z:shortTitle>Fractional photothermolysis for the treatment of acne scars</z:shortTitle>
<dc:identifier>
<dcterms:URI>
<rdf:value>http://www.ncbi.nlm.nih.gov/pubmed/18273724</rdf:value>
</dcterms:URI>
</dc:identifier>
<dcterms:dateSubmitted>2010-12-06 11:36:52</dcterms:dateSubmitted>
<z:libraryCatalog>NCBI PubMed</z:libraryCatalog>
<dc:description>PMID: 18273724</dc:description>
</bib:Article>
<bib:Journal rdf:about="urn:issn:0954-6634">
<dc:title>The Journal of Dermatological Treatment</dc:title>
<prism:volume>19</prism:volume>
<prism:number>1</prism:number>
<dcterms:alternative>J Dermatolog Treat</dcterms:alternative>
<dc:identifier>DOI 10.1080/09546630701691244</dc:identifier>
<dc:identifier>ISSN 0954-6634</dc:identifier>
</bib:Journal>
解决方法:
rdf容器一般都很痛苦,处理起来很烦人.我发布了两个解决方案,一个没有SPARQL,另一个没有SPARQL.我个人更喜欢第二个,即使用SPARQL的那个.
示例1：没有SPARQL
要获得给定文章的所有作者,就像你的情况一样,你可以做到
类似于我在下面发布的代码.
我添加了评论,以便自我解释.最重要的一点
是基本上使用g.triple(triple_pattern)与此图函数
您可以过滤rdflib图并搜索所需的三重模式.
当解析rdf：Seq时,然后谓词形式：
http://www.w3.org/1999/02/22-rdf-syntax-ns#_1
http://www.w3.org/1999/02/22-rdf-syntax-ns#_2
http://www.w3.org/1999/02/22-rdf-syntax-ns#_3
创建后,rdflib以随机顺序检索它们,因此您需要对它们进行排序
以正确的顺序遍历它们.
import rdflib
RDF = rdflib.namespace.RDF
#Parse the file
g = rdflib.Graph()
g.parse("zot.rdf")
#So that we are sure we get something back
print "Number of triples",len(g)
#Couple of handy namespaces to use later
BIB = rdflib.Namespace("http://purl.org/net/biblio#")
FOAF = rdflib.Namespace("http://xmlns.com/foaf/0.1/")
#Author counter to print at the bottom
i=0
#Article for wich we want the list of authors
article = rdflib.term.URIRef("http://www.ncbi.nlm.nih.gov/pubmed/18273724")
#First loop filters is equivalent to "get all authors for article x"
for triple in g.triples((article,BIB["authors"],None)):
#This expresions removes the rdf:type predicate cause we only want the bnodes
# of the form http://www.w3.org/1999/02/22-rdf-syntax-ns#_SEQ_NUMBER
# where SEQ_NUMBER is the index of the element in the rdf:Seq
list_triples = filter(lambda y: RDF['type'] != y[1], g.triples((triple[2],None,None)))
#We sort the authors by the predicate of the triple - order in sequences do matter ;-)
# so "http://www.w3.org/1999/02/22-rdf-syntax-ns#_435"[44:] returns 435
# and since we want numberic order we do int(x[1][44:]) - (BTW x[1] is the predicate)
authors_sorted = sorted(list_triples,key=lambda x: int(x[1][44:]))
#We iterate the authors bNodes and we get surname and givenname
for author_bnode in authors_sorted:
for x in g.triples((author_bnode[2],FOAF['surname'],None)):
author_surname = x[2]
for y in g.triples((author_bnode[2],FOAF['givenname'],None)):
author_name = y[2]
print "author(%s): %s %s"%(i,author_name,author_surname)
i += 1
此示例显示如何在不使用SPARQL的情况下执行此操作.
示例2：使用SPARQL
现在有完全相同的例子,但使用SPARQL.
rdflib.plugin.register('sparql', rdflib.query.Processor,
'rdfextras.sparql.processor', 'Processor')
rdflib.plugin.register('sparql', rdflib.query.Result,
'rdfextras.sparql.query', 'SPARQLQueryResult')
query = """
SELECT ?seq_index ?name ?surname WHERE {
<http://www.ncbi.nlm.nih.gov/pubmed/18273724> bib:authors ?seq .
?seq ?seq_index ?seq_bnode .
?seq_bnode foaf:givenname ?name .
?seq_bnode foaf:surname ?surname .
}
"""
for row in sorted(g.query(query, initNs=dict(rdf=RDF,foaf=FOAF,bib=BIB)),
key=lambda x:int(x[0][44:])):
print "Author(%s) %s %s"%(row[0][44:],row[1],row[2])
如图所示,我们仍然需要进行排序,因为库本身并不处理它.在查询中,变量seq_index包含谓词,该谓词包含有关序列顺序的信息,并且是在lambda函数中进行排序的谓词.