stag.neo4j.Neo4jGraph Class Reference

Inheritance diagram for stag.neo4j.Neo4jGraph:

Description

Represent a neo4j database as a stag.graph.LocalGraph object.

This provides 'local' access to the graph only. Given a node, we can query its neighbors and its degree. The graph does not support weighted edges, and it does not distinguish between edge types or directions.

The neo4j <id> attributes are used as the STAG vertex ids.

All methods which make calls to the database backend have a small cache of recent queries, meaning that consecutive queries for the same node will be fast.

Public Member Functions
def	__init__ (self, str uri, str username, str password)
	Connect to a neo4j database backend.
def	degree (self, v)
	Equivalent to stag.neo4j.Neo4jGraph.degree_unweighted.
int	degree_unweighted (self, int v)
	Query the degree of the node with the given neo4j ID.
List[graph.Edge]	neighbors (self, int v)
	Fetch the neighbors of the node with the given Neo4j node ID.
List[int]	neighbors_unweighted (self, int v)
	Fetch the neighbors of the node with the given Neo4j node ID.
List[str]	query_node_labels (self, int node_id)
	Query the labels of the given node.
int	query_id (self, str property_name, str property_value)
	Find the Neo4j ID of a node with the given property.
str	query_property (self, int id, str property_name)
	Find the requested property of a Neo4j node.
bool	vertex_exists (self, int v)
	Given a vertex ID, returns true or false to indicate whether the vertex exists in the graph.
Public Member Functions inherited from stag.graph.LocalGraph
def	__init__ (self)
	Default LocalGraph constructor.
float	degree (self, int v)
	Given a vertex v, return its weighted degree.
int	degree_unweighted (self, int v)
	Given a vertex v, return its unweighted degree.
List[Edge]	neighbors (self, int v)
	Given a vertex v, return a list of edges representing the neighbors of v.
np.ndarray	neighbors_unweighted (self, int v)
	Given a vertex v, return a list of neighbors of v.
np.ndarray	degrees (self, np.ndarray vertices)
	Given a list of vertices, return a list of their weighted degrees.
np.ndarray	degrees_unweighted (self, np.ndarray vertices)
	Given a list of vertices, return a list of their unweighted degrees.
bool	vertex_exists (self, int v)
	Given a vertex ID, returns true or false to indicate whether the vertex exists in the graph.

Public Attributes
	driver
	The neo4j database driver object used to query the underlying database.

Constructor & Destructor Documentation

__init__()

def stag.neo4j.Neo4jGraph.__init__	(		self,
		str	uri,
		str	username,
		str	password
	)

Connect to a neo4j database backend.

For example, assuming that there is a Neo4j database running locally, the graph object can be created as follows.

import stag.neo4j
g = stag.neo4j.Neo4jGraph("bolt://localhost:7687", "neo4j", "password")

It is also possible to connect to a remote Neo4j database by passing the relevant uri to the constructor.

Parameters

uri	the location of the neo4j database
username	the neo4j username
password	the neo4j password

Reimplemented from stag.graph.LocalGraph.

Member Function Documentation

degree()

def stag.neo4j.Neo4jGraph.degree	(		self,
			v
	)

Equivalent to stag.neo4j.Neo4jGraph.degree_unweighted.

Reimplemented from stag.graph.LocalGraph.

degree_unweighted()

int stag.neo4j.Neo4jGraph.degree_unweighted	(		self,
		int	v
	)

Query the degree of the node with the given neo4j ID.

Reimplemented from stag.graph.LocalGraph.

neighbors()

List[graph.Edge] stag.neo4j.Neo4jGraph.neighbors	(		self,
		int	v
	)

Fetch the neighbors of the node with the given Neo4j node ID.

The returned stag.graph.Edge objects all have weight 1.

Reimplemented from stag.graph.LocalGraph.

neighbors_unweighted()

List[int] stag.neo4j.Neo4jGraph.neighbors_unweighted	(		self,
		int	v
	)

Fetch the neighbors of the node with the given Neo4j node ID.

Returns the Neo4j node IDs of the neighboring nodes.

Reimplemented from stag.graph.LocalGraph.

query_node_labels()

List[str] stag.neo4j.Neo4jGraph.query_node_labels	(		self,
		int	node_id
	)

Query the labels of the given node.

For example, using the Neo4j movie database example, you can query whether a given node represents a person or a movie as follows.

>>> import stag.neo4j
>>> g = stag.neo4j.Neo4jGraph("bolt://localhost:7687", "neo4j", "password")
>>> labels = g.query_node_labels(0)
['Movie']
>>> labels = g.query_node_labels(1)
['Person']

query_id()

int stag.neo4j.Neo4jGraph.query_id	(		self,
		str	property_name,
		str	property_value
	)

Find the Neo4j ID of a node with the given property.

For example, using the Neo4j movie database example you can find the Neo4j node corresponding to a given movie as follows.

import stag.neo4j
g = stag.neo4j.Neo4jGraph("bolt://localhost:7687", "neo4j", "password")
node_id = g.query_id("title", "Avatar")

This will make a query to the database to find a node with the given property. This query will be slow unless the database has an index for property_name. For more information, see the Neo4j documentation on creating an index.

Parameters

property_name	the node property to query
property_value	the value of the node property to search for

Returns

the Neo4j node ID of a node with the given property value. Returns None if there is no node in the dataabase with the requested property.

query_property()

str stag.neo4j.Neo4jGraph.query_property	(		self,
		int	id,
		str	property_name
	)

Find the requested property of a Neo4j node.

For example, using the Neo4j movie database example, you can find the title of a movie node as follows.

import stag.neo4j
g = stag.neo4j.Neo4jGraph("bolt://localhost:7687", "neo4j", "password")
title = g.query_property(1, "title")

Parameters

id	the Neo4j node ID to query
property_name	the name of the property to query

Returns

the value of the requested property on the given node. Returns None if the requested property is not set on the requested node, or if the node id does not exist.

vertex_exists()

bool stag.neo4j.Neo4jGraph.vertex_exists	(		self,
		int	v
	)

Given a vertex ID, returns true or false to indicate whether the vertex exists in the graph.

Parameters

v	the vertex index to check

Returns

a boolean indicating whether there exists a vertex with the given index

Reimplemented from stag.graph.LocalGraph.

Member Data Documentation

driver

stag.neo4j.Neo4jGraph.driver

The neo4j database driver object used to query the underlying database.