Loading a NetworkX graph

Another way to construct a graph from client-side data is by using the library’s convenience NetworkX loading method. In order to use this method, one has to install NetworkX support for the graphdatascience library:

pip install graphdatascience[networkx]

The method that exposes the NetworkX dataset loading functionality is called gds.graph.datasets.networkx.load. It returns Graph object, and takes three arguments:

Table 1. NetworkX graph loading method arguments
Name	Type
`nx_G`	`networkx.Graph`	A graph in the NetworX format
`graph_name`	`str`	The name of the created GDS graph
`concurrency`	`int = 4`	An optional number of threads to use

Exactly how the networkx.Graph nx_G maps to a GDS Graph projection is outlined in detail below.

Example

Let’s look at an example of loading a minimal heterogeneous toy NetworkX graph.

Example of loading a directed NetworkX graph

import networkx as nx

# Construct a directed NetworkX graph
nx_G = nx.DiGraph()
nx_G.add_node(1, labels=["Person"], age=52)
nx_G.add_node(42, labels=["Product", "Item"], cost=17.2)
nx_G.add_edge(1, 42, relationshipType="BUYS", quantity=4)

# Load the graph into GDS
G = gds.graph.datasets.networkx.load(nx_G, "purchases")

# Verify that the projection is what we expect
assert G.name() == "purchases"
assert G.node_count() == 2
assert set(G.node_labels()) == {"Person", "Product", "Item"}
assert G.node_properties()["Person"] == ["age"]
assert G.node_properties()["Product"] == ["cost"]
# Count rel not being = 2 indicates the graph is indeed directed
assert G.relationship_count() == 1
assert G.relationship_types() == ["BUYS"]
assert G.relationship_properties()["BUYS"] == ["quantity"]

Combined with NetworkX’s functionality for reading various graph formats one can easily load popular graph formats like edge list and GML into GDS.

Combined with NetworkX’s functionality for generating various kinds of graphs one can easily load graph types popular in the literature into GDS, such as expanders, lollipop graphs, complete graphs, and more.

NetworkX schema to GDS schema

There are some rules as to how the NetworkX graph maps to the projected Graph in GDS. They follow principles similar to those of graph-object.adoc#construct, and are outlined in detail in this section.

Node labels

Node labels for the projected GDS graph are taken from attributes on networkx.Graph nodes. The values of node attribute key labels will dictate what labels nodes are given in the projection. These values should be either strings or lists of strings.

Either all nodes of the networkx.Graph must have valid labels attributes, or they can be completely left out from the graph. That is, a networx.Graph with no labels node attributes at all is also allowed. In this latter case, the nodes in the projected Graph will all have the node label N.

Node properties

Node properties for the projected GDS graph are taken from attributes on networkx.Graph nodes. The keys of the attributes will map to property names, and the allowed values must follow the regular guidelines for node property values in GDS. Please note though that the node attribute key labels is reserved for node labels (previous section) and will not translate to node properties in the projection.

Relationship types

Relationship types for the projected GDS graph are taken from attributes on networkx.Graph edges. The values of edge attribute key relationshipType will dictate what types relationships are given in the projection. These values should be either strings or omitted.

Either all edges of the networkx.Graph must have valid relationshipType attributes, or they can be completely left out from the graph. That is, a networx.Graph with no relationshipType edge attributes at all is also allowed. In this latter case, the relationships in the projected Graph will all have the relationship type R.

Relationship properties

Relationship properties for the projected GDS graph are taken from attributes on networkx.Graph edges. The keys of the attributes will map to property names, and the allowed values must follow the regular guidelines for relationship property values in GDS. Please note though that the edge attribute key relationshipType is reserved for relationship types (previous section) and will not translate to relationship properties in the projection.

Relationship direction

The direction (DIRECTED or UNDIRECTED) of the relationships in the projected GDS graph are inferred from the type of networkx.Graph used. If the given NetworkX graph is directed, so a (sub)class of either networkx.DiGraph or networkx.MultiDiGraph, the relationships will be DIRECTED in the projection. Otherwise, they will be UNDIRECTED.

Limitations on community edition

For users of GDS community edition, performance can be impacted for large graphs. It is possible that socket connection with the database times out. If this happens, a possible workaround is to modify the server configuration server.bolt.connection_keep_alive or server.bolt.connection_keep_alive_probes. However, be aware of the side effects such as a genuine connection issue now taking longer to be detected.