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sparqlite

Quick start

This guide will help you make your first SPARQL query using sparqlite with the OpenCitations Meta endpoint.

Basic usage

Section titled “Basic usage”
from sparqlite import SPARQLClient


with SPARQLClient("https://opencitations.net/meta/sparql") as client:
    # Execute a SELECT query to find journal articles
    result = client.query("""
        PREFIX fabio: <http://purl.org/spar/fabio/>
        PREFIX dcterms: <http://purl.org/dc/terms/>
        PREFIX datacite: <http://purl.org/spar/datacite/>
        PREFIX literal: <http://www.essepuntato.it/2010/06/literalreification/>


        SELECT ?article ?title ?doi WHERE {
            ?article a fabio:JournalArticle ;
                     dcterms:title ?title ;
                     datacite:hasIdentifier ?id .
            ?id datacite:usesIdentifierScheme datacite:doi ;
                literal:hasLiteralValue ?doi .
        }
        LIMIT 10
    """)


    # Iterate over results (SPARQL JSON format)
    for row in result["results"]["bindings"]:
        print(f"{row['title']['value']}: {row['doi']['value']}")

The context manager ensures the HTTP connection is properly closed when done and enables connection reuse for multiple queries.

Checking results

Section titled “Checking results”

You can check if a query returned results and get the number of rows:

with SPARQLClient("https://opencitations.net/meta/sparql") as client:
    result = client.query("""
        PREFIX fabio: <http://purl.org/spar/fabio/>


        SELECT ?article WHERE {
            ?article a fabio:JournalArticle .
        }
        LIMIT 100
    """)


    # Check if there are results
    bindings = result["results"]["bindings"]
    if bindings:
        print(f"Found {len(bindings)} results")


    # Get variable names
    print(f"Variables: {result['head']['vars']}")

Different query types

Section titled “Different query types”

sparqlite supports all SPARQL query types:

with SPARQLClient("https://opencitations.net/meta/sparql") as client:
    # SELECT - returns tabular results
    result = client.query("""
        PREFIX fabio: <http://purl.org/spar/fabio/>
        PREFIX dcterms: <http://purl.org/dc/terms/>


        SELECT ?article ?title WHERE {
            ?article a fabio:JournalArticle ;
                     dcterms:title ?title .
        }
        LIMIT 5
    """)


    # ASK - returns True or False
    exists = client.ask("""
        PREFIX datacite: <http://purl.org/spar/datacite/>
        PREFIX literal: <http://www.essepuntato.it/2010/06/literalreification/>


        ASK {
            ?id datacite:usesIdentifierScheme datacite:doi ;
                literal:hasLiteralValue "10.1162/qss_a_00023" .
        }
    """)
    if exists:
        print("This DOI exists in OpenCitations!")


    # CONSTRUCT - returns raw N-Triples bytes
    result = client.construct("""
        PREFIX fabio: <http://purl.org/spar/fabio/>
        PREFIX dcterms: <http://purl.org/dc/terms/>


        CONSTRUCT {
            ?article dcterms:title ?title .
        }
        WHERE {
            ?article a fabio:JournalArticle ;
                     dcterms:title ?title .
        }
        LIMIT 10
    """)
    print(result.decode())


    # DESCRIBE - returns raw N-Triples bytes
    result = client.describe("""
        PREFIX fabio: <http://purl.org/spar/fabio/>
        PREFIX dcterms: <http://purl.org/dc/terms/>


        DESCRIBE ?journal WHERE {
            ?journal a fabio:Journal ;
                     dcterms:title ?title .
        }
        LIMIT 1
    """)
    print(result.decode())

Next steps

Section titled “Next steps”