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Corese-library with Python.md

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Getting Started With Corese-python (beta)

1. Setup and run

  1. Install java and python
  2. Install python dependencies pip install --user py4j
  3. Download corese-library-python-4.5.0.jar
  4. Place in the same directory corese-library-python-4.5.0.jar and your code myCode.py
  5. Run with python myCode.py

2. Template

Python script template:

import atexit
import subprocess
from time import sleep

from py4j.java_gateway import JavaGateway


# Start java gateway
java_process = subprocess.Popen(
    ['java', '-jar', '-Dfile.encoding=UTF-8', 'corese-library-python-4.5.0.jar'])
sleep(1)
gateway = JavaGateway()


# Stop java gateway at the enf od script
def exit_handler():
    gateway.shutdown()
    print('\n' * 2)
    print('Gateway Server Stop!')

atexit.register(exit_handler)


#######################
# Type your code here #
#######################

3. A functional example

Here is an example of a python script that shows how to :

  • Build a graph by program (Corese API);
  • Execute a SPARQL query;
  • Load a graph from a file;
  • Export a graph to a file.
import atexit
import subprocess
from time import sleep

from py4j.java_gateway import JavaGateway

# Start java gateway
java_process = subprocess.Popen(
    ['java', '-jar', '-Dfile.encoding=UTF-8', 'corese-library-python-4.5.0.jar'])
sleep(1)
gateway = JavaGateway()


def exit_handler():
    # Stop java gateway at the enf od script
    gateway.shutdown()
    print('\n' * 2)
    print('Gateway Server Stop!')


atexit.register(exit_handler)

# Import of class
Graph = gateway.jvm.fr.inria.corese.core.Graph
Load = gateway.jvm.fr.inria.corese.core.load.Load
Transformer = gateway.jvm.fr.inria.corese.core.transform.Transformer
QueryProcess = gateway.jvm.fr.inria.corese.core.query.QueryProcess
RDF = gateway.jvm.fr.inria.corese.core.logic.RDF

###############
# Build Graph #
###############


def BuildGraphCoreseApi():
    """Build a graph with a single statement (Edith Piaf is a singer) with the Corese API
    :returns: graph with a single statement (Edith Piaf is a singer)
    """
    corese_graph = Graph()

    # NameSpace
    ex = "http://example.org/"

    # Create and add statement: Edith Piaf is an Singer
    edith_Piaf_IRI = corese_graph.addResource(ex + "EdithPiaf")
    rdf_Type_Property = corese_graph.addProperty(RDF.TYPE)
    singer_IRI = corese_graph.addResource(ex + "Singer")

    corese_graph.addEdge(edith_Piaf_IRI, rdf_Type_Property, singer_IRI)

    return corese_graph

##########
# Sparql #
##########


def sparqlQuery(graph, query):
    """Run a query on a graph

    :param graph: the graph on which the query is executed
    :param query: query to run
    :returns: query result
    """
    exec = QueryProcess.create(graph)
    return exec.query(query)


#################
# Load / Export #
#################


def exportToFile(graph, format, path):
    """Export a graph to a file

    :param graph: graph to export
    :param format: format of export
    :param path: path of the exported file
    """
    transformer = Transformer.create(graph, format)
    transformer.write(path)


def load(path):
    """Load a graph from a local file or a URL

    :param path: local path or a URL
    :returns: the graph load
    """
    graph = Graph()

    ld = Load.create(graph)
    ld.parse(path)

    return graph


########
# Main #
########


def printTitle(title):
    title = "== " + title + " =="
    border = "=" * len(title)
    print("\n" * 2)
    print(border)
    print(title)
    print(border)


###
# Build a graph with the Corese API
###
printTitle("Build a graph with the Corese API")

graph = BuildGraphCoreseApi()
print("Graph build ! (" + str(graph.size()) + " triplets)")

print("\nPrint Graph:")
print(graph.display())


###
# SPARQL Query
###
printTitle("SPARQL Query")

graph = load(
    "https://raw.githubusercontent.com/stardog-union/stardog-tutorials/master/music/beatles.ttl")
print("Graph load ! (" + str(graph.size()) + " triplets)")

# List of U2 albums
query = """
        prefix : <http://stardog.com/tutorial/>

        SELECT ?member 
        WHERE {
            ?The_Beatles :member ?member
        }
        """

map = sparqlQuery(graph, query)
print("\nQuery result ! (List of members of bands \"The Beatles\"): ")
print(map)


###
# Load / Export
###
printTitle("Load / Export")

graph = load(
    "https://raw.githubusercontent.com/stardog-union/stardog-tutorials/master/music/beatles.ttl")
print("Graph load ! (" + str(graph.size()) + " triplets)")

path_export_file = "export.rdf"
exportToFile(graph, Transformer.RDFXML, path_export_file)
print("Graph Export in file (" + path_export_file + ")")

Results :

Gateway Server Started



=======================================
== Build a graph with the Corese API ==
=======================================
Graph build ! (1 triplets)

Print Graph:
predicate rdf:type [1]
00 kg:default <http://example.org/EdithPiaf> rdf:type <http://example.org/Singer>




==================
== SPARQL Query ==
==================
Graph load ! (28 triplets)

Query result ! (List of members of bands "The Beatles"): 
01 ?member = <http://stardog.com/tutorial/John_Lennon>; 
02 ?member = <http://stardog.com/tutorial/Paul_McCartney>; 
03 ?member = <http://stardog.com/tutorial/Ringo_Starr>; 
04 ?member = <http://stardog.com/tutorial/George_Harrison>; 




===================
== Load / Export ==
===================
Graph load ! (28 triplets)
Graph Export in file (export.rdf)



Gateway Server Stop!

4. Options

  • -p, --port : port of the java gateway server (default: 25333).
  • -c, --config, --init : path of the Corese config file, (See a example on GitHub).