Introduction to py2neo

Introducing py2neonigel@nigelsmall.name py2neo.org@technige @py2neo

Where does py2neo fit in? (your app) py2neo GET /db/data/ 200 OK REST Server Neo4j

Coming Up...● Connecting & Creating● Property Containers● Indexes & Uniqueness● Cypher & Geoff● Installation● Future Plans

Connecting & Creating

Default Connections>>> from py2neo import neo4j>>> graph_db = neo4j.GraphDatabaseService() default connection is made to <http://localhost:7474/db/data/>

Custom Connections>>> from py2neo import neo4j>>> uri = "http://otherserv:9999/db/data/">>> graph_db = neo4j.GraphDatabaseService(uri)>>> graph_db.neo4j_version(1, 8, uM04, 1, ug892e348)

A few simple methods...>>> graph_db.get_node(0)Node(http://localhost:7474/db/data/node/0)>>> graph_db.get_reference_node()Node(http://localhost:7474/db/data/node/0)>>> graph_db.get_node_count()1>>> graph_db.get_relationship_count()0

Sample data: a family tree m (1947) Phil (1921) Liz (1926) Chaz (1948) Anne (1950) Andy (1960) Ed (1964)All characters appearing in this work are fictitious. Any resemblance to real persons, living or dead, is purely coincidental.

list of nodes createnodes = graph_db.create( Phil Liz {"name": "Phil", "born": 1921}, {"name": "Liz", "born": 1926}, {"name": "Chaz", "born": 1948}, {"name": "Anne", "born": 1950}, Chaz Anne {"name": "Andy", "born": 1960}, {"name": "Ed", "born": 1964},) Andy Ed

list of relationships create MARRIEDrels = graph_db.create( Phil Liz (phil, "MARRIED", liz), (chaz, "FATHER", phil), FATHER MOTHER (chaz, "MOTHER", liz), Chaz) node must already exist

createfamily = graph_db.create( {"name": "Phil", "born": 1921}, {"name": "Liz", "born": 1926}, {"name": "Chaz", "born": 1948}, {"name": "Anne", "born": 1950}, {"name": "Andy", "born": 1960}, {"name": "Ed", "born": 1964}, (0, "MARRIED", 1, {"year": 1947, "place": "London"}), (2, "FATHER", 0), (3, "FATHER", 0), (4, "FATHER", 0), (5, "FATHER", 0), (2, "MOTHER", 1), (3, "MOTHER", 1), (4, "MOTHER", 1), (5, "MOTHER", 1),)

list of nodes and relationships createfamily = graph_db.create( {"name": "Phil", "born": 1921}, {"name": "Liz", "born": 1926}, {"name": "Chaz", "born": 1948}, {"name": "Anne", "born": 1950}, {"name": "Andy", "born": 1960}, {"name": "Ed", "born": 1964}, (0, "MARRIED", 1, {"year": 1947, "place": "London"}), (2, "FATHER", 0), (3, "FATHER", 0), relationship (4, "FATHER", 0), (5, "FATHER", 0), properties (2, "MOTHER", 1), (3, "MOTHER", 1), (4, "MOTHER", 1), (5, "MOTHER", 1),) node defined in same batchnodes, rels = family[0:6], family[6:]phil, liz, chaz, anne, andy, ed = nodes

Property Containers

neo4j.PropertyContainer PropertyContainer Node Relationship

PropertyContainers implement many of the container methods defined by the Python standard<http://docs.python.org/reference/datamodel.html#emulating-container-types>

neo4j.PropertyContainer set property# update propertiesliz["star_sign"] = "Taurus"# query properties get property test propertyfor node in nodes: containment name = node["name"] if "star_sign" in node: print name + " is a node["star_sign"] else: print name + " doesnt believe in horoscopes"

neo4j.Node PropertyContainerNode Relationship

Relationships and Related Nodes Chazparental_rels = liz.get_relationships( Liz neo4j.Direction.INCOMING, "MOTHER" Anne) Chazparental_rels = liz.get_relationships_with( Liz chaz, neo4j.Direction.INCOMING, "MOTHER" Anne) Chazchildren = liz.get_related_nodes( Liz neo4j.Direction.INCOMING, "MOTHER" Anne)

Relationships and Related Nodes>>> liz.has_relationship(neo4j.Direction.BOTH, "MARRIED")True>>> anne.is_related_to(phil, neo4j.Direction.OUTGOING, "FATHER")True>>> ed.is_related_to(andy, neo4j.Direction.BOTH, "BROTHER")False could also specify multiple types

neo4j.Relationship PropertyContainerNode Relationship

neo4j.Relationship>>> rels[0].start_nodeNode(http://localhost:7474/db/data/node/1)>>> rels[0].end_nodeNode(http://localhost:7474/db/data/node/2)>>> rels[0].typeMARRIED

More sample data: a second tree m George (1895) Betty (1900) Liz (1926) Maggie (1930)

m George (1895) Betty (1900) Liz (1926) Maggie (1930) m (1947) Phil (1921) Liz (1926)Chaz (1948) Anne (1950) Andy (1960) Ed (1964)

m George (1895) Betty (1900) same person Liz (1926) Maggie (1930) m (1947) Phil (1921) Liz (1926)Chaz (1948) Anne (1950) Andy (1960) Ed (1964)

How can we avoidduplicate nodes?

Indexes

Indexing the first family...>>> people = graph_db.get_or_create_index(neo4j.Node, "People")>>> for node in nodes:... people.add("name", node["name"], node)>>> people.get("name", "Liz")[Node(http://localhost:7474/db/data/node/2)] list of matching entities

...and the second>>> new_props = [... {"name": "George", "born": 1895},... {"name": "Betty", "born": 1900},... {"name": "Liz", "born": 1926},... {"name": "Maggie", "born": 1930},... ]>>> george, betty, liz, maggie = [... people.get_or_create("name", prop["name"], prop)... for prop in new_props same node... ] as before>>> people.get("name", "Liz")[Node(http://localhost:7474/db/data/node/2)]

A Quick Query>>> people.query("name:*e*")[Node(http://localhost:7474/db/data/node/4),Node(http://localhost:7474/db/data/node/7),Node(http://localhost:7474/db/data/node/8),Node(http://localhost:7474/db/data/node/9)] People George name Andy name Anne Maggie name Betty name Chaz name Ed name George Anne name Liz name Maggie Betty name Phil

Weve added thenodes... what about the relationships?

Cypher & Geoff

Cypher RELATESTART a=node(1), b=node(2)RELATE (a)-[ab:KNOWS]->(b)RETURN ab

Cypher RELATEa b RELATE a ba b RELATE a b !a b RELATE

relatenew_rels = graph_db.relate( (george, "MARRIED", betty), (liz, "FATHER", george), (maggie, "FATHER", george), (liz, "MOTHER", betty), (maggie, "MOTHER", betty), George MARRIED Betty) FATHER FATHER MOTHER MOTHER Liz Maggie

For relationships,relate can be seen as an idempotent alternative to create

cypher.execute>>> from py2neo import cypher>>> query = "START q=node(1) RETURN q">>> data, metadata = cypher.execute(graph_db, query)>>> for row in data:... q = row[0]... print q first column

cypher.execute>>> from py2neo import cypher>>> query = "START q=node(1) RETURN q">>> data, metadata = cypher.execute(graph_db, query) available only after all rows received>>> for row in data:... q = row[0]... print q first column

cypher.executequery = "START q=node(1) RETURN q" executed once per row as eachdef print_row(row): row is received q = row[0] print rowcypher.execute(graph_db, query, row_handler=print_row)

Command Line Cypherelgin@forge:~% cypher "start a=node(1) match (a)-[:MARRIED]->(b) return a, b"+------------------------------------------------------------------+| a | b |+------------------------------------------------------------------+| (1) {"name":"Phil","born":1921} | (2) {"name":"Liz","born":1926} |+------------------------------------------------------------------+elgin@forge:~% cypher -f csv "start a=node(1) match (a)-[ab:MARRIED]->(b) return a, ab, b""a","ab","b""(1)","(1)-[0:MARRIED]->(2)","(2)"elgin@forge:~% cypher -f json "start a=node(1) match (a)-[ab:MARRIED]->(b) return a, ab, b"[ {"a": "(1)", "ab": "(1)-[0:MARRIED]->(2)", "b": "(2)"}]elgin@forge:~% cypher -f geoff "start a=node(1) match (a)-[ab:MARRIED]->(b) return a, ab, b"(1) {"name": "Phil", "born": 1921}(2) {"name": "Liz", "born": 1926}(1)-[0:MARRIED]->(2) {"year": 1947, "place": "London"}

Geoff is to graph data asCSV is to tabular data <http://geoff.nigelsmall.net/>

elgin@forge:~% cypher -f geoff "start n=node(*), r=rel(*) return n, r"(0) {}(1) {"born": 1921, "name": "Phil", "family": "Windsor"}(2) {"born": 1926, "star_sign": "Taurus", "family": "Windsor", "name": "Liz"}(3) {"born": 1948, "name": "Chaz", "family": "Windsor"}(4) {"born": 1950, "name": "Anne", "family": "Windsor"}(5) {"born": 1960, "name": "Andy", "family": "Windsor"}(6) {"born": 1964, "name": "Ed", "family": "Windsor"}(7) {"born": 1895, "name": "George"}(8) {"born": 1900, "name": "Betty"}(9) {"born": 1930, "name": "Maggie"}(1)-[0:MARRIED]->(2) {"place": "London", "year": 1947}(3)-[1:FATHER]->(1) {}(4)-[2:FATHER]->(1) {}(5)-[3:FATHER]->(1) {}(6)-[4:FATHER]->(1) {}(3)-[5:MOTHER]->(2) {}(4)-[6:MOTHER]->(2) {}(5)-[7:MOTHER]->(2) {}(6)-[8:MOTHER]->(2) {}(7)-[9:MARRIED]->(8) {}(2)-[10:FATHER]->(7) {}(9)-[11:FATHER]->(7) {}(2)-[12:MOTHER]->(8) {}(9)-[13:MOTHER]->(8) {}

Neo4j Console

Installation

Requirements● Python 2.6+ <http://python.org/>● Tornado 2.2.1 <http://www.tornadoweb.org/>● Neo4j 1.6+ <http://neo4j.org/>

Installation <http://pypi.python.org/pypi/py2neo>elgin@forge:~% sudo pip install py2neoelgin@forge:~% sudo pip install --upgrade py2neo

Source Code <https://github.com/nigelsmall/py2neo>elgin@forge:~% git clone git@github.com:nigelsmall/py2neo.git

Future Plans● Fast HTTP● Multi-threading support● Python 3● Command line tools● Property caching● Test harness for multiple Neo4j versions● New methods, e.g. get_paths_to

EOFnigel@nigelsmall.name py2neo.org@technige @py2neo

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Introduction to py2neo

by Nigel Small on Jun 29, 2012

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