如何使用rdflib（或plain sparql）访问rdf列表的成员

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>
    
2019-09-05 3 条评论
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    迪擅哨乘傅

    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。     
    2019-09-05 0 0
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    壤欠攻混

    在
    RDFLib
    的新版本中，可以以更简化的方式访问集合。现在可以使用
    Seq
    类以编程方式访问序列中的成员： 
    from rdflib import *
from rdflib.graph import Seq
from rdflib.namespace import FOAF
BIB = Namespace("http://purl.org/net/biblio#")

# Load data
g = Graph()
g.parse(file=open("./zotero.rdf", "r"), format="application/rdf+xml")

# Get the first resource linked to article via bib:authors
article = URIRef("http://www.ncbi.nlm.nih.gov/pubmed/18273724")
authors = g.objects(article, BIB.authors).__next__()
i = 1
for author in Seq(g, authors):
    givenname = g.triples((author, FOAF.givenname, None)).__next__()[2]
    surname = g.triples((author, FOAF.surname, None)).__next__()[2]
    print("%i: %s %s" % (i, str(givenname), str(surname)))
    i += 1
        
    2019-09-05 0 0
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