Neo4J contains all Query - neo4j

Question

I'm brand new to neo4j and graph databases.
I'm trying to create a query I would describe as a 'contains all' however I think I'm very far away and not sure how to progress
MATCH (movie:Movie {name:'tropic thunder'})-[:stars_in]-(actors)
-[:guest_stars_in]-(movie2)
RETURN movie2.name
Let's say
MATCH (movie:Movie{name:'tropic thunder'})-[:stars_in]-(actors)
returns 5 actors
I'm looking to match exactly (all 5 actors -> same 5 actors as guest stars) or as a subset (all 5 actors are a subset of a movie which has 10 guest stars).
Hope that makes sense. Thanks for your help :D

Answer 1

The first thing I would point out is that you should call the variable actor instead of actors. It may seem picky, but it's a common confusion with Cypher. With the MATCH you are matching one sub-pattern at a time.
So to start out let's find each movie2 and get an array of the actors in question:
MATCH (movie:Movie {name:'tropic thunder'})-[:stars_in]-(actor)
-[:guest_stars_in]-(movie2)
RETURN movie2.name, collect(actor)
A first instinct might be to extend the path like so:
MATCH (movie:Movie {name:'tropic thunder'})-[:stars_in]-(actor)
-[:guest_stars_in]-(movie2)-[:guest_starts_in]-(actor2)
But again, we're matching every possible match of that path in the database. So for each actor, we're going to match all possible actor2s, which would lead to duplicates.
What we can do, though, is to take our first query and change the RETURN to a WITH in order to pass our data onto a second part of the query:
MATCH (movie:Movie {name:'tropic thunder'})-[:stars_in]-(actor)
-[:guest_stars_in]-(movie2)
WITH movie2, collect(actor) AS original_movie_actors
MATCH movie2-[:guest_stars_in]-(guest_star)
RETURN movie2.name, original_movie_actors, collect(guest_star) AS guest_stars
This gives us
a list of movies in question
the list of the actors who both stared in "tropic thunder" and guest stared in the movie in question
all guest stars for the movie in question
From here you could probably figure it out in your programming language of choice. But we can figure this out in Cypher too:
MATCH (movie:Movie {name:'tropic thunder'})-[:stars_in]-(actor)
-[:guest_stars_in]-(movie2)
WITH movie2, collect(actor) AS original_movie_actors
MATCH movie2-[:guest_stars_in]-(guest_star)
WITH movie2, original_movie_actors, collect(guest_star) AS guest_stars
RETURN
movie.name,
ALL(guest_star IN guest_stars WHERE guest_star IN original_movie_actors) AS all_matched,
length(original_movie_actors) / length(guest_stars) AS percentage_match
I threw in a percentage_match as a double-check and in case that's useful