Lab: RDF programming with RDFlib: Difference between revisions

Latest revision as of 13:20, 28 January 2024

Topics

RDF graph programming with RDFlib

Useful materials

RDFLib:

Lab Presentations:

RDFlib classes/interfaces:

from rdflib import Graph, Namespace, URIRef, BNode, Literal
from rdflib.namespace import RDF, FOAF, XSD
from rdflib.collection import Collection

RDFlib methods:

Graph: add(), remove(), triples(), serialize(), parse(), bind()

Tasks

Continue with the graph you created in Exercise 1.

Task: Continue to extend your graph:

Michael Cohen was Donald Trump's attorney.
- He pleaded guilty for lying to Congress.
Michael Flynn was adviser to Donald Trump.
- He pleaded guilty for lying to the FBI.
- He negotiated a plea agreement.

If you want, you can try to use properties and types from standard vocabularies like FOAF (friend-of-a-friend) and DC (Dublin Core), but this is something we will look at in later exercises.

Task: According to this FRONTLINE article, Gates', Cohen's and Flynn's lying were different and are described in different detail.

How can you represent "different instances of lying" as triples?
How can you modify your knowledge graph to account for this?

Task: It is possible to solve the task above without blank (or anonymous nodes). But to do so, you need to create a URI for each "instance of lying". This is a situation where blank nodes may be more suitable. Change your graph so it represents instances of lying as blank nodes.

Task: Save (serialize) your graph to a Turtle file. Add a few triples to the Turtle file with more information about Donald Trump. For example, you can add that Donald Trump is married to Melania and has several children. You can also use blank nodes to represent two of Trump's addresses when he was president:

The White House, 1600 Pennsylvania Ave., NW Washington, DC 20500, United States, phone: 1-202-456-1414
Mar-a-Lago Club, 1100 S Ocean Blvd, Palm Beach, FL 33480, United States

Visualise the result if you want. Read (parse) the Turtle file back into a Python program, and check that the new triples are there.

If you have more time...

Task: Write a method (function) that starts with Donald Trump prints out a graph depth-first to show how the other graph nodes are connected to him. An excerpt of the output could be:

ex:Donald_Trump
    <== ex:campaignManager ex:Paul_Manafort
        ==> ex:convictedFor ex:BankAndTaxFraud
        ...
    <== ex:attorneyFor ex:Michael_Cohen
        ==> ex:pleadedGuilty ex:LyingToCongress

Here, the <== and ==> arrows are printed to indicate the reverse of a property. We do that with a print() statement in Python, not from inside rdflib.

Note: Because you must follow triples in both subject-to-predicate and predicate-to-subject direction, you must keep a list of already visited nodes, and never return to a previously visited one.

Note: If you want a neat solution, it may be best to combine two graph traversals: first traverse the model breadth-first to create a new tree-shaped model, and then traverse the tree-shaped model depth-first to print it out with indentation. (The point of the first breadth-first step is to find the shortest path to each node.)

@@ Line 1: / Line 1: @@
+==Topics==
+* RDF graph programming with RDFlib
-=Lab 2: RDF programming with RDFlib=
+==Useful materials==
+RDFLib:
+* [https://rdflib.readthedocs.io/en/stable/intro_to_creating_rdf.html Creating Triples]
+* [https://rdflib.readthedocs.io/en/stable/rdf_terms.html RDF Terms]
+* [https://rdflib.readthedocs.io/en/stable/namespaces_and_bindings.html Namespaces and Bindings]
+* [https://rdflib.readthedocs.io/en/stable/intro_to_graphs.html Navigating Graphs]
+* [https://rdflib.readthedocs.io/en/stable/intro_to_parsing.html Serialising and parsing]
-==Topics==
+Lab Presentations:
-* Basic RDF graph programming with RDFlib.
+* [https://docs.google.com/presentation/d/1blXlTTTsL8jqeV5sRLhQuZ-nssNZqH_bjSgjj-kougE/edit?usp=sharing Lab 1 - RDF Presentation]
-* Simple reading/writing from/to file.
+* [https://docs.google.com/presentation/d/17yuNqn66fhEIHPE65PyFC0H359q1k6CquE6ojDV0NB4/edit?usp=sharing Lab 2 - More RDF Presentation]
-* Simple looping trough graph
-* Setting up groups for the group project
+RDFlib classes/interfaces:
+* from rdflib import Graph, Namespace, URIRef, BNode, Literal
+* from rdflib.namespace import RDF, FOAF, XSD
+* from rdflib.collection import Collection
-==Classes/interfaces==
+RDFlib methods:
-from rdflib import Graph, Namespace, URIRef, BNode, Literal
+* Graph: add(), remove(), triples(), serialize(), parse(), bind()
-from rdflib.namespace import RDF, FOAF, XSD
-from rdflib.collection import Collection
 ==Tasks==
-Consider the following situation:
+Continue with the graph you created in [[Lab: Getting started with VSCode, Python and RDFlib | Exercise 1]].
-"Cade lives in 1516 Henry Street, Berkeley, California 94709,
-USA. He has a B.Sc. in biology from the University of California,
-Berkeley from 2011. His interests include birds, ecology, the
-environment, photography and travelling. He has visited Canada and
-France. Emma Dominguez lives in Carrer de la Guardia Civil 20, 46020
-Valencia, Spain. She has a M.Sc. in chemistry from the University of
-Valencia from 2015. Her areas of expertise include waste management,
-toxic waste, air pollution. Her interests include bike riding, music
-and travelling. She has visited Portugal, Italy, France, Germany,
-Denmark and Sweden. Cade knows Emma. They met in Paris in August
-."
-(Make up your own URIs when you need to (like "http://example.org/"), or even better: use terms
-you know from vocabularies such as FOAF and RDF.
-Create a graph in RDFlib with triples corresponding to the text above.
+'''Task:''' Continue to extend your graph:
+* Michael Cohen was Donald Trump's attorney.
+** He pleaded guilty for lying to Congress.
+* Michael Flynn was adviser to Donald Trump.
+** He pleaded guilty for lying to the FBI.
+** He negotiated a plea agreement.
+If you want, you can try to use properties and types from standard vocabularies like FOAF (friend-of-a-friend) and DC (Dublin Core), but this is something we will look at in later exercises.
-Write out your graph to the console. I have found that this is seems to be the cleanest way of printing the graph:
+'''Task:''' According to [https://www.pbs.org/wgbh/frontline/article/the-mueller-investigation-explained-2/ this FRONTLINE article], Gates', Cohen's and Flynn's lying were different and are described in different detail.
-print(g.serialize(format="turtle").decode())
+* How can you represent "different instances of lying" as triples?
-Try all the following formats: "turtle", "n3", "nt", "xml". How do they differ? What is the default?
+* How can you modify your knowledge graph to account for this?
-Write your graph to a file. To do this, you can simply use the location parameter e.g: g.serialize(destination="triples.txt", format="turtle").
+'''Task:''' It is possible to solve the task above without blank (or anonymous nodes). But to do so, you need to create a URI for each "instance of lying". This is a situation where blank nodes may be more suitable. Change your graph so it represents instances of lying as blank nodes.
-Look at the file and edit it so that Cade has also visited Germany and so that Emma is 26 years old.
+'''Task:''' Save (''serialize'') your graph to a Turtle file. Add a few triples ''to the Turtle file'' with more information about Donald Trump. For example, you can add that Donald Trump is married to Melania and has several children. You can also use blank nodes to represent two of Trump's addresses when he was president:
+* The White House, 1600 Pennsylvania Ave., NW Washington, DC 20500, United States, phone: 1-202-456-1414
+* Mar-a-Lago Club, 1100 S Ocean Blvd, Palm Beach, FL 33480, United States
+Visualise the result if you want. Read (''parse'') the Turtle file back into a Python program, and check that the new triples are there.
-Create a new program that reads your graph in again from the file and
+==If you have more time...==
-writes it to the console. Check that your new data is there!
-Continuing with either your first or second program, write a loop that
+'''Task:''' Write a method (function) that starts with Donald Trump prints out a graph depth-first to show how the other graph nodes are connected to him. An excerpt of the output could be:
-goes through all the triples in the graph and prints them to the
+ ex:Donald_Trump
-console.
+     <== ex:campaignManager ex:Paul_Manafort
+         ==> ex:convictedFor ex:BankAndTaxFraud
+         ...
+     <== ex:attorneyFor ex:Michael_Cohen
+         ==> ex:pleadedGuilty ex:LyingToCongress
-Change the loop so that (a) it only loops through triples about
+Here, the <== and ==> arrows are printed to indicate the reverse of a property. We do that with a ''print()'' statement in Python, not from inside rdflib.
-Emma (b) it only loops through triples involving the names of
-people.
-Remove all triples about Mary using graph.remove(). (triples of Mary are from lab 1)
+''Note:'' Because you must follow triples in both subject-to-predicate and predicate-to-subject direction, you must keep a list of already visited nodes, and never return to a previously visited one.
-==If you have more time...==
+''Note:'' If you want a neat solution, it may be best to combine two graph traversals: first traverse the model breadth-first to create a new tree-shaped model, and then traverse the tree-shaped model depth-first to print it out with indentation. (The point of the first breadth-first step is to find the shortest path to each node.)
-Below are four lines of comma-separated values (csv - five lines with
+<!--
-the headers) that could have been saved from a spreadsheet. Copy them
+==Triples you can extend for the tasks (turtle format)==
-into a file and write a program with a loop that reads each line from that file (except
+<syntaxhighlight>
-the initial header line) and adds it to your graph as triples:
+@prefix ex: <http://example.org/> .
-  "Name","Gender","Country","Town","Expertise","Interests"
+ex:Mueller_Investigation ex:involved ex:George_Papadopoulos,
-  "Regina Catherine Hall","F","Great Britain","Manchester","Ecology, zoology","Football, music travelling"
+        ex:Michael_Cohen,
-  "Achille Blaise","M","France","Nancy","","Chess, computer games"
+        ex:Michael_Flynn,
-  "Nyarai Awotwi Ihejirika","F","Kenya","Nairobi","Computers, semantic networks","Hiking, botany"
+        ex:Paul_Manafort,
-  "Xun He Zhang","M","China","Chengdu","Internet, mathematics, logistics","Dancing, music, trombone"
+        ex:Rick_Gates,
+        ex:Roger_Stone ;
+    ex:leadBy ex:Robert_Muller .
-In the resulting graph, delete all information about Achille.
+ex:Paul_Manafort ex:businessManager ex:Rick_Gates ;
+    ex:campaignChairman ex:Donald_Trump ;
+    ex:chargedWith ex:ForeignLobbying,
+        ex:MoneyLaundering,
+        ex:TaxEvasion ;
+    ex:convictedFor ex:BankFraud,
+        ex:TaxFraud ;
+    ex:negoiated ex:PleaBargain ;
+    ex:pleadGuiltyTo ex:Conspiracy ;
+    ex:sentencedTo ex:Prison .
-==Useful Links==
+ex:Rick_Gates ex:chargedWith ex:ForeignLobbying,
+        ex:MoneyLaundering,
+        ex:TaxEvasion ;
+    ex:pleadGuiltyTo ex:Conspiracy,
+        ex:LyingToFBI .
-* [https://rdflib.readthedocs.io/en/stable/index.html rdflib documentation]:
+</syntaxhighlight>
+-->