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Build a recommendation engine with Python and Neo4jMark Needham / @markhneedham
Logistics
‣ Download and install Neo4j 3.0.0• http://neo4j.com/download/
‣ Open your browser to http://localhost:7474
Introducing our data set...
meetup.com’s recommendations
Recommendation queries
‣ Several different types• groups to join• topics to follow• events to attend
‣ As a user of meetup.com trying to find groups to join and events to attend
The data
meetup.com/meetup_api/
What data do we have?
‣ Groups‣ Members‣ Events‣ Topics‣ Time & Date‣ Location
Find similar groups to Neo4j
As a member of the Neo4j London group
I want to find other similar meetup groups
So that I can join those groups
What makes groups similar?
Find similar groups to Neo4j
As a member of the Neo4j London group
I want to find other similar meetup groups
So that I can join those groups
Nodes
As a member of the Neo4j London group
I want to find other similar meetup groups
So that I can join those groups
Relationships
As a member of the Neo4j London group
I want to find other similar meetup groups
So that I can join those groups
Labels
As a member of the Neo4j London group
I want to find other similar meetup groups
So that I can join those groups
Properties
As a member of the Neo4j London group
I want to find other similar meetup groups
So that I can join those groups
‣ Open your browser to http://localhost:7474 if you haven’t already
‣ Type the following command::play http://guides.neo4j.com/pydata
Recommend groups by topic
When there are slides to see
Follow AlongLet’s go through the first guide
Take NoteIndexes
Indexes
We create indexes to:
‣ allow fast lookup of nodes which match these (label,property) pairs.
Indexes
We create indexes to:
‣ allow fast lookup of nodes which match these (label,property) pairs.
CREATE INDEX ON :Group(name)
The following are index backed:‣ Equality‣ STARTS WITH‣ CONTAINS, ‣ ENDS WITH‣ Range searches‣ (Non-)existence checks
Indexes
How does Neo4j use indexes?
Indexes are only used to find the starting point for queries.
Use index scans to look up rows in tables and join them with rows from other tables
Use indexes to find the starting points for a query.
Relational
Graph
ContinueContinue with the Guide
ExerciseExplore the Graph
SolutionExplore the Graph
ContinueContinue with the Guide
Next StepClustering topics
Next StepGroup Membership
Exclude groups I’m a member of
As a member of the Neo4j London group
I want to find other similar meetup groupsthat I’m not already a member of
So that I can join those groups
Group memberships
Next GuideGroup Membership
Watch OutTransactions & WITH
Periodic Commit
Cypher keeps all transaction state in memory while running a query which is fine most of the time.
Periodic Commit
Cypher keeps all transaction state in memory while running a query which is fine most of the time.
But when using LOAD CSV, this state can get very large and may result in an OutOfMemory exception.
Periodic Commit
// defaults to 1000
USING PERIODIC COMMIT
LOAD CSV
...
Periodic Commit
// defaults to 1000
USING PERIODIC COMMIT 10000
LOAD CSV
...
WITH
The WITH clause allows query parts to be chained together, piping the results from one to be used as starting points or criteria in the next.
WITH
It’s used to:
‣ limit the number of entries that are then passed on to other MATCH clauses.
‣ filter on aggregated values‣ separate reading from updating of the graph
ContinueContinue with the Guide
ExerciseFind yourself and your groups
SolutionFind yourself and your groups
ContinueContinue with the Guide
Next GuideEvent recommendations
ExerciseExtend event recommendations
SolutionExtend event recommendations
That’s all for today!
Mark Needham / @markhneedham
