Visualize an RDFLIB Graph in Python

问题

I am new to RDFLIB in python. I found this example of creating a graph on here. What is the simplest way to visualize graph created by this code?

import rdflib
# Now we create a graph, a representaiton of the ontology
g = rdflib.Graph()

# Now define the key words that we will use (the edge weights of the graph)
has_border_with = rdflib.URIRef('http://www.example.org/has_border_with')
located_in = rdflib.URIRef('http://www.example.org/located_in')

# define the things - base level objects that will be the nodes
# In this case first we have countries
germany = rdflib.URIRef('http://www.example.org/country1')
france = rdflib.URIRef('http://www.example.org/country2')
china = rdflib.URIRef('http://www.example.org/country3')
mongolia = rdflib.URIRef('http://www.example.org/country4')

# then we have continents
europa = rdflib.URIRef('http://www.example.org/part1')
asia = rdflib.URIRef('http://www.example.org/part2')

# Having defined the things and the edge weights, now assemble the graph
g.add((germany,has_border_with,france))
g.add((china,has_border_with,mongolia))
g.add((germany,located_in,europa))
g.add((france,located_in,europa))
g.add((china,located_in,asia))
g.add((mongolia,located_in,asia))

I see that the rdflib package has a tools component that has a function called rdfs2dot. How can I use this function to display a plot with the RDF graph in it?

回答1:

Using the hint in this question: https://www.researchgate.net/post/Is_there_any_open_source_RDF_graph_converter

I was able to plot the RDF Graph by converting to Networkx Graph and using the Networkx/Matplotlib plotting tools.

import rdflib
from rdflib.extras.external_graph_libs import rdflib_to_networkx_multidigraph
import networkx as nx
import matplotlib.pyplot as plt

url = 'https://www.w3.org/TeamSubmission/turtle/tests/test-30.ttl'

g = rdflib.Graph()
result = g.parse(url, format='turtle')

G = rdflib_to_networkx_multidigraph(result)

# Plot Networkx instance of RDF Graph
pos = nx.spring_layout(G, scale=2)
edge_labels = nx.get_edge_attributes(G, 'r')
nx.draw_networkx_edge_labels(G, pos, labels=edge_labels)
nx.draw(G, with_labels=True)

To visualise large RDF Graphs the styling might need some finetuning ;-)

回答2:

I could make a picture of your RDF Graph with rdf2dot, as you suggested. Nevertheless I am not completely happy with that library since it makes no nodes for literals. This is my code:

!pip install pydotplus
!pip install graphviz

import io
import pydotplus
from IPython.display import display, Image
from rdflib.tools.rdf2dot import rdf2dot

def visualize(g):
    stream = io.StringIO()
    rdf2dot(g, stream, opts = {display})
    dg = pydotplus.graph_from_dot_data(stream.getvalue())
    png = dg.create_png()
    display(Image(png))

visualize(g)

Giving the following result:

来源：https://stackoverflow.com/questions/39274216/visualize-an-rdflib-graph-in-python

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python

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rdflib