Download pdf - Neo4j and Python: Playing with graph data - PyCon India 2014 Talk

PyCon India 2014• • created by Sonal Raj •

Neo4j and Python Playing with graph data

Graph Everything

Sonal Raj

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The Plan for today

Graphs and NOSQL

Step One

Neo4j and Cypher

Step Two

4Step Two

Use CasesPy2neo and

REST

Step Two



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Once upon a time..



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Once upon a time..• Relational databases ruled the earth . .

• Data was stored in Tables, Rows and Columns

• Connections using Primary keys, Foreign keys . .

• That’s all that is relational about then

• No on-the-fly structural (schema) changes

• Horrible for Interconnected data ( joins, really? )



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In the NOSQL Space



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In the NOSQL Space



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In the NOSQL Space



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In the NOSQL Space



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In the NOSQL Space

RDBMS



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In the NOSQL Space

Elastic scaling – Scale out, not up



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In the NOSQL Space


Big data, Transaction Friendly



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In the NOSQL Space



Economical, can run on commodity hardware



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In the NOSQL Space




End of the DBA rule



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In the NOSQL Space




End of the DBA rule

Flexible Data models



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Graph Trivia


Where are Graphs . . .



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Some Graphswe overlook . .



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Apart from that

Fraud AnalysesInvestment securities &debt analysis

RecommendationEngines

Impact Analysis innetworks



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So, Why Graphs ?

• Increasing Connectivity of Data

• Increasing Semi-Structredness

• Rising Complexity



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So, Why Graphs ?

• Increasing Connectivity of Data

• Increasing Semi-Structredness

• Rising Complexity

Seven Bridges of Königsberg

Leonhard Euler in 1735



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Property Graphs



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Property Graphs

- Has nodes



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Property Graphs

- Has nodes- Has properties for

each node



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Property Graphs


each node- Has Relationships



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Property Graphs


each node- Has Relationships- Has properties for

each relationship



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Building Blocks

Nodes

Relationships

Labels

Graph Database

Properties



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Data Models

Native Graphs

Inherently store data as nodes and relationships.



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Data Models

Native Graphs


The Other ones . . .

Data stored in tables, joins and aggregates to simulate a graph



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Data Models

Native Graphs


The Other ones . . .

Data stored in tables, joins and aggregates to simulate a graph



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Why Neo4j ?

Schema-less property graph



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Why Neo4j ?


Handles complex connected data efficiently



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Why Neo4j ?



Fully ACID Transactions



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Why Neo4j ?




Highly Scalable, High Availability Clusters



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Why Neo4j ?





REST API for servers. Can be embedded to applications on JVM.



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Why Neo4j ?





REST API for servers. Can be embedded to applications on JVM.

Cypher – a declarative querying solution

Graph DB with good native python bindings . .



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Cypher in action

• Highly expressive query language

• Cares about ‘what’ rather than ‘how’ to retrieve from the graph.

• Uses pattern matching expressions.

1 2

(1) – [ :label ] - (2)

label



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Cypher in action




1 2

START n=(1), m=(2)

MATCH n – [r:label] – m

RETURN r

label



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Cypher in action




• To make life easy for some, it is inspired by SQL.

1 2

START n=(1), m=(2)

MATCH n – [r:label] – m

RETURN r

label



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Cypher in actionCreate

Read

CREATE (n:Person { name : ‘Chuck Norris', title : ‘Analyst' })

RETURN n

MATCH (a:Person),(b:Person)

WHERE a.name = ‘Chuck' AND b.name = ‘Rajani'

CREATE (a)-[r:RELTYPE { name : ‘cannot_find’ }]->(b)

RETURN r

MATCH (n) RETURN n #everything is returned

MATCH (n:Label) RETURN n #all with specific label

MATCH (Titanic { title:‘Titanic' })<-[:ACTED_IN|:DIRECTED]-(person)

RETURN person



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Cypher in actionUpdate

Delete

MATCH (n { name: 'Andres' })

SET n.surname = 'Taylor'

RETURN n

MATCH (peter { name: 'Peter' })

SET peter += { hungry: TRUE , position: 'Entrepreneur' }

MATCH (n { name: 'Peter' })

REMOVE n.title

REMOVE n:German

RETURN n

SET n.name = NULL



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REST in peace !!Create

POST http://localhost:7474/db/data/node

{

"foo" : "bar"

}

POST http://localhost:7474/db/data/node/1/relationships

{

"to" : "http://localhost:7474/db/data/node/10",

"type" : "LOVES",

"data" : {

"foo" : "bar"

}

}

POST http://localhost:7474/db/data/schema/index/person

{

"property_keys" : [ "name" ]

}



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REST in peace !!Read

Update

Delete

GET http://localhost:7474/db/data/node/144

GET http://localhost:7474/db/data/relationship/65

GET http://localhost:7474/db/data/relationship/61/properties

GET http://localhost:7474/db/data/schema/index/user

PUT http://localhost:7474/db/data/relationship/66/properties

{

"happy" : false

}

PUT http://localhost:7474/db/data/relationship/60/properties/cost

"deadly"

DELETE http://localhost:7474/db/data/node/308

DELETE http://localhost:7474/db/data/relationship/58

DELETE http://localhost:7474/db/data/schema/index/SomeLabel/name



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Beauty of py2neo


For the pythonistasAs simple as that!

from py2neo import neo4j

graph_db = neo4j.GraphDatabaseService("http://localhost:7474/db/data/")

from py2neo import node, rel die_hard = graph_db.create(

node(name="Bruce Willis"),

node(name="John McClane"),

node(name="Alan Rickman"),

node(name="Hans Gruber"),

node(name="Nakatomi Plaza"),

rel(0, "PLAYS", 1),

rel(2, "PLAYS", 3),

rel(1, "VISITS", 4),

rel(3, "STEALS_FROM", 4),

rel(1, "KILLS", 3),

)



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For the pythonistas

graphdb • clear()

• create(*abstracts)

• delete(*entities)

• delete_index(content_type, index_name)

• find(label, property_key=None, property_value=None)

• get_index(content_type, index_name)

• get_indexed_node(index_name, key, value)

• ...



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For the pythonistas

• get_indexed_relationship(index_name, key, value)

• get_properties(*entities)

• match(start_node=None, rel_type=None, end_node=None,

bidirectional=False, limit=None)

• match_one(start_node=None, rel_type=None, end_node=None,

bidirectional=False)

• node(id_)

• get_or_create_index(content_type, index_name, config=None)

• get_or_create_indexed_node(index_name, key, value,

properties=None)

graphdb



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Complexity Handling

“ A graph database without traversals is just a persistent graph ”



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Paths with py2neo#Create Paths

from py2neo import neo4j, node

a, b, c = node(name="Alice"), node(name="Bob"), node(name="Carol")

abc = neo4j.Path(a, ’KNOWS’, b, ’KNOWS’, c)

d, e = node(name=“Doctor”), node(name=“Easter”)

de = neo4j.Path(d, ‘KNOWS’, e)

#Join paths

abcde = neo4j.Path.join(abc, ‘KNOWS’, de)

#commit to the db

abcde.get_or_create(graph_db)



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Schema, Indices with py2neo#The class

py2neo.neo4j.Schema

py2neo.neo4j.Index

#Join paths

create_index(label, property_key)

drop_index(label, property_key)

get_indexed_property_keys(label)

add_if_none(key, value, entity)

#Apache Lucene Query

people = graph_db.get_or_create_index(neo4j.Node, "People")

s_people = people.query("family_name:S*")



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neo4j.Node

neo4j.Relationship


Cypher with py2neo#Create transaction object

from py2neo import cypher

Session = cypher.Session(“http://localhost:7474/”)

tx = session.create_transaction()

#Add transactions, execute or commit

tx.append(“some cypher query”)


tx.execute()


tx.commit()

#The classical way

from py2neo import neo4j

graph_db = neo4j.GraphDatabaseSercice()

query = neo4j.CypherQuery(graph_db, ‘your cypher query’)

query.execute()

#query.stream()



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Command Line neotool#Syntax of operation

neotool [<option>] <command> <args>

Or python –m py2neo.tool ..

#Some serious examples

neotool clear

neotool cypher "start n=node(1) return n, n.name?“

neotool cypher-csv "start n=node(1) return n.name, n.age?"

neotool cypher-tsv "start n=node(1) return n.name, n.age?"

#Guess what, you can also access the shell

neotool shell



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Neo4j level 2

• Batch Inserter

• High Availability

• Built-in online backup tools

• HTTPS support



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Neo4j level 2

• Batch Inserter

• High Availability

• Built-in online backup tools

• HTTPS support

Neo4J Framework.

• GraphUnit, for unit testing neo4j• Libraries for performance and API testing• Batch Transaction tools• Transaction Event tools• Some other utilities . .



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Use Cases


Recommendation Engines Complex pattern matching



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Social Network Data Many entities, highly interconnected



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Map DataTraversals and routing



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Python FamilyRelatives for Neo4j

Neo4



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• •PyCon India 2014

Thank YouNeo appreciates your patience.

• Sonal Raj

• http://www.sonalraj.com/

• http://github.com/sonal-raj/

• [email protected]



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