num_nodes()#
relationalai.std.graphs.Compute
#num_nodes() -> Expression
Get the number of nodes in the graph. Must be called in a rule or query context.
Supported Graph Types#
Graph Type | Supported | Notes |
---|---|---|
Directed | Yes | |
Undirected | Yes | |
Weighted | Yes | Weights are ignored. |
Unweighted | Yes |
Returns#
Returns an Expression that produces the number of nodes in the graph as an integer value.
Example#
Use .num_nodes()
to get the number of nodes in a graph.
You access the .num_nodes()
method from a Graph
object’s
.compute
attribute:
#import relationalai as rai
from relationalai.std.graphs import Graph
# Create a model named "socialNetwork" with a Person type
model = rai.Model("socialNetwork")
Person = model.Type("Person")
# Add some people to the graph and connect them with a 'friends' property.
with model.rule():
alice = Person.add(name="Alice")
bob = Person.add(name="Bob")
alice.friends.add(bob)
bob.friends.add(alice)
# Create an undirected graph with Person nodes and edges between friends.
graph = Graph(model, undirected=True)
graph.Node.extend(Person)
graph.Edge.extend(Person.friends)
# Get the number of nodes in the graph.
with model.query() as select:
avg_degree = graph.compute.num_nodes()
response = select(avg_degree)
print(response.results)
# Output:
# v
# 0 2