使用Turtle文件的SPARQL查询（公共数据源）

Question

I am new to Turtle format files and querying them with SPARQL. So I have many questions to be solved, I hope you can help me!

I have a file called equipamentsCURT3.ttl and contains the following:

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix v: <http://www.w3.org/2006/vcard/ns#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://opendata.gencat.cat/recursos/equipaments/30883> a v:VCard ;
v:adr [ a v:Work ;
        v:country-name "Spain" ;
        v:locality "Sabadell" ;
        v:postal-code "08202" ;
        v:region "Vallès Occidental" ;
        v:street-address " c.  Sant Josep" ] ;
v:category "2. Parvulari"@ca,
    "3. Educació primària"@ca,
    "4. Educació secundària obligatòria"@ca,
    "Educació. Formació"@ca,
    "Ensenyaments de règim general"@ca ;
v:fn "Escolàpies Sabadell"@ca ;
v:geo [ v:latitude 4.154826e+01 ;
        v:longitude 2.111243e+00 ] ;
v:nickname "Escolàpies Sabadell"@ca ;
v:tel [ a v:Pref,
            v:Tel,
            v:Work ;
        rdf:value "937255348" ] .

<http://opendata.gencat.cat/recursos/equipaments/31264> a v:VCard ;
v:adr [ a v:Work ;
        v:country-name "Spain" ;
        v:locality "Molins de Rei" ;
        v:postal-code "08750" ;
        v:region "Baix Llobregat" ;
        v:street-address " c.  Ntra. Sra. de Lourdes" ] ;
v:category "4. Educació secundària obligatòria"@ca,
    "7. Batxillerat"@ca,
    "8. Cicles formatius d'FP de grau mitjà (CFPM)"@ca,
    "9. Cicles formatius d'FP de grau superior (CFPS)"@ca,
    "Educació. Formació"@ca,
    "Ensenyaments de règim general"@ca ;
v:fn "Institut Bernat el Ferrer"@ca ;
v:geo [ v:latitude 4.14105e+01 ;
        v:longitude 2.02704e+00 ] ;
v:nickname "Institut Bernat el Ferrer"@ca ;
v:tel [ a v:Pref,
            v:Tel,
            v:Work ;
        rdf:value "936683762" ] .

<http://opendata.gencat.cat/recursos/equipaments/31265> a v:VCard ;
v:adr [ a v:Work ;
        v:country-name "Spain" ;
        v:locality "Castellar del Vallès" ;
        v:postal-code "08211" ;
        v:region "Vallès Occidental" ;
        v:street-address " NC  Bonavista" ] ;
v:category "2. Parvulari"@ca,
    "3. Educació primària"@ca,
    "Educació. Formació"@ca,
    "Ensenyaments de règim general"@ca ;
v:fn "Escola Bonavista"@ca ;
v:geo [ v:latitude 4.161903e+01 ;
        v:longitude 2.091745e+00 ] ;
v:nickname "Escola Bonavista"@ca ;
v:tel [ a v:Pref,
            v:Tel,
            v:Work ;
        rdf:value "937144195" ] .

I am using Python3.5 and a library called RDFLib ( https://github.com/RDFLib/rdflib ). I need to read from a file called equipamentsCURT.rdf, serialize it into equipamentsCURT3.ttl and then retrieve all information related to an equipment. For example, for the equipment 30883 ( http://opendata.gencat.cat/recursos/equipaments/30883 ), I want v:adr,v:category,v:fn,v:geo and v:tel . To obtain this data, I use SPARQL but I don't know why the query doesn't work. I'm very confused in how to query the information.

Here is my code:

import rdflib , pprint
from rdflib import URIRef, Graph
from rdflib.plugins import sparql

g = Graph()
g.load("equipamentsCURT3.ttl", format='turtle')

queryTest = 'prefix v: <http://www.w3.org/2006/vcard/ns#> ' \
'select ?y where {?x  a <http://opendata.gencat.cat/recursos/equipaments 30883>; ?y v:VCard .}'
qresult = g.query(queryTest)

for st in qresult:
 print rdflib.term.Literal(st).value

Answer 1

The whole query doesn't make any sense nor does it match the data. I'd suggest reading a SPARQL tutorial first. The whole query looks like copy-paste from something else + some random stuff from your side.

1. the URI http://opendata.gencat.cat/recursos/equipaments 30883 contains a white space which is wrong

2. http://opendata.gencat.cat/recursos/equipaments/30883 is not a class. Thus, a triple pattern ?xa <http://opendata.gencat.cat/recursos/equipaments/30883> , which means to all resources that belong to the class http://opendata.gencat.cat/recursos/equipaments/30883 doesn't match your data.

3. The second triple pattern is ?x ?yv:VCard . And you're selecting the predicate ?y as the final result of your query. But you want the objects for a given subject and a given set of predicates. Syntax of a triple /resp. triple pattern) is subject-predicate-object. Thus, for example for v:category it should be

PREFIX v: <http://www.w3.org/2006/vcard/ns#> 
SELECT ?o WHERE {
  <http://opendata.gencat.cat/recursos/equipaments/30883>  v:category ?o 
}

For the other properties it will be more complicated since the values itself are blank nodes that have attached multiple values via additional properties. Eg for v:adr it would be

PREFIX v: <http://www.w3.org/2006/vcard/ns#> 
SELECT ?p ?o WHERE {
  <http://opendata.gencat.cat/recursos/equipaments/30883>  v:adr ?adr .
  ?adr ?p ?o 
}

Update

If you don't want the values but the properties it's correct to have the variable in predicate position. But it's wrong to restrict it to those properties that occur only in triples with the object v:VCard because there is no such property besides rdf:type ( a is just a synonym for it). In that case it should be

PREFIX v: <http://www.w3.org/2006/vcard/ns#> 
SELECT DISTINCT ?p WHERE {
  <http://opendata.gencat.cat/recursos/equipaments/30883>  ?p ?o 
}