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Knowledge Graph¶

Build a knowledge graph to organize information about entities and their relationships.

What You'll Learn¶

Modeling diverse entity types
Creating semantic relationships
Querying for insights
Traversing knowledge paths

The Domain: Movies¶

We'll build a knowledge graph about movies, actors, directors, and genres.

Setup¶

import grafeo

db = grafeo.Database()

Create the Knowledge Graph¶

with db.session() as session:
    # Movies
    session.execute("""
        INSERT (:Movie {
            title: 'The Matrix',
            year: 1999,
            rating: 8.7
        })
        INSERT (:Movie {
            title: 'Inception',
            year: 2010,
            rating: 8.8
        })
        INSERT (:Movie {
            title: 'The Dark Knight',
            year: 2008,
            rating: 9.0
        })
    """)

    # People
    session.execute("""
        INSERT (:Person {name: 'Keanu Reeves', born: 1964})
        INSERT (:Person {name: 'Leonardo DiCaprio', born: 1974})
        INSERT (:Person {name: 'Christian Bale', born: 1974})
        INSERT (:Person {name: 'Christopher Nolan', born: 1970})
        INSERT (:Person {name: 'Lana Wachowski', born: 1965})
    """)

    # Genres
    session.execute("""
        INSERT (:Genre {name: 'Sci-Fi'})
        INSERT (:Genre {name: 'Action'})
        INSERT (:Genre {name: 'Thriller'})
    """)

Create Relationships¶

with db.session() as session:
    # Acting relationships
    session.execute("""
        MATCH (p:Person {name: 'Keanu Reeves'}), (m:Movie {title: 'The Matrix'})
        INSERT (p)-[:ACTED_IN {role: 'Neo'}]->(m)
    """)
    session.execute("""
        MATCH (p:Person {name: 'Leonardo DiCaprio'}), (m:Movie {title: 'Inception'})
        INSERT (p)-[:ACTED_IN {role: 'Cobb'}]->(m)
    """)
    session.execute("""
        MATCH (p:Person {name: 'Christian Bale'}), (m:Movie {title: 'The Dark Knight'})
        INSERT (p)-[:ACTED_IN {role: 'Batman'}]->(m)
    """)

    # Directing relationships
    session.execute("""
        MATCH (p:Person {name: 'Christopher Nolan'}), (m:Movie {title: 'Inception'})
        INSERT (p)-[:DIRECTED]->(m)
    """)
    session.execute("""
        MATCH (p:Person {name: 'Christopher Nolan'}), (m:Movie {title: 'The Dark Knight'})
        INSERT (p)-[:DIRECTED]->(m)
    """)
    session.execute("""
        MATCH (p:Person {name: 'Lana Wachowski'}), (m:Movie {title: 'The Matrix'})
        INSERT (p)-[:DIRECTED]->(m)
    """)

    # Genre relationships
    session.execute("""
        MATCH (m:Movie {title: 'The Matrix'}), (g:Genre {name: 'Sci-Fi'})
        INSERT (m)-[:IN_GENRE]->(g)
    """)
    session.execute("""
        MATCH (m:Movie {title: 'The Matrix'}), (g:Genre {name: 'Action'})
        INSERT (m)-[:IN_GENRE]->(g)
    """)
    session.execute("""
        MATCH (m:Movie {title: 'Inception'}), (g:Genre {name: 'Sci-Fi'})
        INSERT (m)-[:IN_GENRE]->(g)
    """)
    session.execute("""
        MATCH (m:Movie {title: 'Inception'}), (g:Genre {name: 'Thriller'})
        INSERT (m)-[:IN_GENRE]->(g)
    """)
    session.execute("""
        MATCH (m:Movie {title: 'The Dark Knight'}), (g:Genre {name: 'Action'})
        INSERT (m)-[:IN_GENRE]->(g)
    """)

Query the Knowledge Graph¶

Find Christopher Nolan's Movies¶

with db.session() as session:
    result = session.execute("""
        MATCH (p:Person {name: 'Christopher Nolan'})-[:DIRECTED]->(m:Movie)
        RETURN m.title, m.year, m.rating
        ORDER BY m.year
    """)

    print("Christopher Nolan's movies:")
    for row in result:
        print(f"  {row['m.title']} ({row['m.year']}) - {row['m.rating']}")

Find Sci-Fi Movies¶

with db.session() as session:
    result = session.execute("""
        MATCH (m:Movie)-[:IN_GENRE]->(g:Genre {name: 'Sci-Fi'})
        RETURN m.title, m.rating
        ORDER BY m.rating DESC
    """)

    print("Sci-Fi movies:")
    for row in result:
        print(f"  {row['m.title']} ({row['m.rating']})")

Find Co-Stars¶

with db.session() as session:
    result = session.execute("""
        MATCH (a1:Person)-[:ACTED_IN]->(m:Movie)<-[:ACTED_IN]-(a2:Person)
        WHERE a1 <> a2
        RETURN a1.name, a2.name, m.title
    """)

    print("Co-stars:")
    for row in result:
        print(f"  {row['a1.name']} and {row['a2.name']} in {row['m.title']}")

Next Steps¶