min_degree()#

relationalai.std.graphs.Compute
min_degree() -> Expression

Compute the minimum degree of all nodes a graph. For an undirected graph, the degree of a node is the number of neighbors it has in the graph. In a directed graph, the degree of a node is the sum of its indegree and outdegree. Must be called in a rule or query context.

Supported Graph Types#

Graph TypeSupportedNotes
DirectedYes
UndirectedYes
WeightedYesWeights are ignored.
UnweightedYes

Returns#

Returns an Expression object that produces the minimum degree of the graph as an integer value.

Example#

Use .min_degree() to compute the minimum degree of a node in a graph. You access the .min_degree() 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")
    carol = Person.add(name="Carol")
    alice.friends.extend([bob, carol])
    bob.friends.add(alice)
    carol.friends.add(alice)

# Create an undirected graph with Person nodes and edges between friends.
# This graph has two edges: one between Alice and Bob and one between Alice and Carol.
graph = Graph(model, undirected=True)
graph.Node.extend(Person)
graph.Edge.extend(Person.friends)

# Compute the minimum degree of the graph.
with model.query() as select:
    min_degree = graph.compute.min_degree()
    response = select(min_degree)

print(response.results)
# Output:
#    v
# 0  1

In directed graphs, the degree of a node is the sum of its indegree and outdegree:

# Create a directed graph with Person  nodes and edges between friends.
# Note that graphs are directed by default.
# This graph has four edges: two between Alice and Bob and two between Alice and Carol.
directed_graph = Graph(model)
directed_graph.Node.extend(Person)
directed_graph.Edge.extend(Person.friends)

# Compute the minimum degree of the directed graph.
with model.query() as select:
    min_degree = directed_graph.compute.min_degree()
    response = select(min_degree)

print(response.results)
# Output:
#    v
# 0  2

See Also#