relationalai.std.graphs.EdgeInstance

class relationalai.std.graphs.EdgeInstance

EdgeInstance is a subclass of Producer that produces edges in a graph. They are created by called a graph’s Edge object or the Edge.add() method. An EdgeInstance is similar to an Instance, but rather than representing an object, it represents a pairs of objects. As a result, you can’t add EdgeInstance objects to a Type.

Example

import relationalai as rai
from relationalai.std.graphs import Graph

# Create a model with a 'Person' type.
model = rai.Model("socialNetwork")
Person = model.Type("Person")

# Add people to the model connected by a multi-valued 'follows' property.
with model.rule():
    alice = Person.add(name="Alice")
    bob = Person.add(name="Bob")
    alice.follows.add(bob)

# Create a directed graph.
graph = Graph(model)

# Add edges to the graph from the 'Person.follows' property.
graph.Edge.extend(Person.follows, type="follows")

# Query the edges in the graph.
with model.query() as select:
    # 'edge' is an EdgeInstance object.
    edge = graph.Edge()
    # Use the '.from_' and '.to' attributes to access the nodes
    # connected by the edge, and the '.type' attribute to access
    # the edge's 'type' property.
    response = select(edge.from_.name, edge.to.name, edge.type)

print(response.results)
# Output:
#     name name2        v
# 0  Alice   Bob  follows

# Use the '.set()' method to set properties on an edge.
with model.rule():
    edge = graph.Edge()
    # Set the 'weight' property of all edges to 1.0.
    edge.set(weight=1.0)
    # NOTE: Setting the 'weight' property does not turn the graph
    # into a weighted graph. You can only create a weighted graph
    # by passing 'weighted=True' to the 'Graph' constructor.

# Query the edges in the graph.
with model.query() as select:
    edge = graph.Edge()
    response = select(edge.from_.name, edge.to.name, edge.weight)

print(response.results)
# Output:
#     name name2    v
# 0  Alice   Bob  1.0

Attributes

Name	Type	Description
.from_	Producer	The node at the start of the edge.
.to	Producer	The node at the end of the edge.

.from_

EdgeInstance.from_

Returns a Producer object that produces the node at the start of an edge:

import relationalai as rai
from relationalai.std.graphs import Graph

# Create a model with a 'Person' type.
model = rai.Model("socialNetwork")
Person = model.Type("Person")

# Add people to the model connected by a multi-valued 'follows' property.
with model.rule():
    alice = Person.add(name="Alice")
    bob = Person.add(name="Bob")
    alice.follows.add(bob)

# Create a directed graph with 'Person' nodes and 'follows' edges.
graph = Graph(model)
graph.Edge.extend(Person.follows)

# Get the names of all people following Bob.
with model.query() as select:
    edge = graph.Edge(to=Person(name="Bob"))
    follower = edge.from_
    response = select(follower.name)

print(response.results)
# Output:
#     name
# 0  Alice

.to

EdgeInstance.to

Returns a Producer object that produces the terminal node of an edge:

import relationalai as rai
from relationalai.std.graphs import Graph

# Create a model with a 'Person' type.
model = rai.Model("socialNetwork")
Person = model.Type("Person")

# Add people to the model connected by a multi-valued 'follows' property.
with model.rule():
    alice = Person.add(name="Alice")
    bob = Person.add(name="Bob")
    alice.follows.add(bob)

# Create a directed graph with 'Person' nodes and 'follows' edges.
graph = Graph(model)
graph.Edge.extend(Person.follows)

# Get the names of all people Alice follows.
with model.query() as select:
    edge = graph.Edge(from_=Person(name="Alice"))
    follows = edge.to
    response = select(follows.name)

print(response.results)
# Output:
#   name
# 0  Bob

Methods

Name	Description	Returns
.set()	Set properties on an edge.	EdgeInstance

.set()

EdgeInstance.set(**kwargs) -> EdgeInstance

Sets properties on an EdgeInstance object and returns the EdgeInstance. Note that unlike Instance.set(), you can’t set a Type on an edge. Must be called in a rule or query context.

Parameters

Name	Type	Description
*kwargs	Any	Properties and values to set on the EdgeInstance.

Returns

An EdgeInstance object.

Example

import relationalai as rai
from relationalai.std.graphs import Graph

# Create a model with a 'Person' type.
model = rai.Model("socialNetwork")
Person = model.Type("Person")

# Add people to the model connected by a multi-valued 'follows' property.
with model.rule():
    alice = Person.add(name="Alice")
    bob = Person.add(name="Bob")
    alice.follows.add(bob)

# Create a directed graph with 'Person' nodes and 'follows' edges.
graph = Graph(model)
graph.Edge.extend(Person.follows)

# Set the 'color' property of all edges to 'red'.
with model.rule():
    edge = graph.Edge()
    edge.set(color="red")

# Query the edges in the graph.
with model.query() as select:
    edge = graph.Edge()
    response = select(edge.from_.name, edge.to.name, edge.color)

print(response.results)
# Output:
#     name name2    v
# 0  Alice   Bob  red