GraphAdapter

GraphAdapter()

Abstract base class providing a unified API to any graph engine.

A node or edge that is not on the graph is a GraphError from every method that takes one, except get_node, which answers None for an unknown id. Backend exceptions never pass through the adapter boundary.

Methods

Name	Description
add_node	Add a node to the graph.
add_edge	Add an edge from source to target to the graph.
remove_node	Remove a node (and its incident edges) from the graph.
remove_edge	Remove an edge from the graph.
get_node	Return the node with the given id, or None if there is no such node.
get_edge	Return the edge of the given type from source to target; raises GraphError if there is none.
filter_edges	Returns a list of all edges for which filter_function(edge) returns True.
filter_nodes	Returns a list of all nodes for which filter_function(node) returns True.
get_edge_endpoints	Return the source and target nodes of the given edge as a tuple (source, target).
get_source_of_edge	Return the source node of the given edge.
get_target_of_edge	Return the target node of the given edge.
has_node	Return True if node is present in the graph.
has_edge	Return True if an edge (optionally of the given type) exists from source to target.
num_nodes	Return the total number of nodes in the graph.
num_edges	Return the total number of edges in the graph.
nodes	Iterate over nodes, optionally filtered by node_type and/or predicate.
edges	Iterate over edges, optionally filtered by edge_type and/or predicate.
edges_between	Iterate over edges from source to target, optionally filtered by edge_type.
successors	Iterate over nodes reachable from node via an outgoing edge, optionally filtered.
predecessors	Iterate over nodes that have an outgoing edge to node, optionally filtered.
get_next	Return the next node connected by an edge of type NEXT from the given node, if it exists.
get_previous	Return the previous node connected by an edge of type NEXT to the given node, if it exists.
neighbors	Iterate over all nodes adjacent to node (predecessors and successors), optionally filtered.
out_edges	Iterate over edges originating from node, optionally filtered by edge_type.
in_edges	Iterate over edges terminating at node, optionally filtered by edge_type.
incident_edges	Iterate over all edges touching node (incoming and outgoing), optionally filtered by edge_type.
degree	Return the total number of edges incident to node.
in_degree	Return the number of edges terminating at node.
out_degree	Return the number of edges originating from node.

add_node

add_node(node: OmkObject)

Add a node to the graph.

add_edge

add_edge(source: OmkObject, target: OmkObject, edge: OmkEdge)

Add an edge from source to target to the graph.

Raises GraphError if there is already an edge of the same type between source and target, or if the edge is a NEXT and the source already has one out or the target one in.

remove_node

remove_node(node: OmkObject)

Remove a node (and its incident edges) from the graph.

remove_edge

remove_edge(edge: OmkEdge)

Remove an edge from the graph.

get_node

get_node(node_id: UUID | str)

Return the node with the given id, or None if there is no such node.

get_edge

get_edge(source: OmkObject, target: OmkObject, edge_type: EdgeType)

Return the edge of the given type from source to target; raises GraphError if there is none.

filter_edges

filter_edges(filter_function: Callable[[OmkEdge], bool])

Returns a list of all edges for which filter_function(edge) returns True.

filter_nodes

filter_nodes(filter_function: Callable[[OmkObject], bool])

Returns a list of all nodes for which filter_function(node) returns True.

get_edge_endpoints

get_edge_endpoints(edge: OmkEdge)

Return the source and target nodes of the given edge as a tuple (source, target).

get_source_of_edge

get_source_of_edge(edge: OmkEdge)

Return the source node of the given edge.

get_target_of_edge

get_target_of_edge(edge: OmkEdge)

Return the target node of the given edge.

has_node

has_node(node: OmkObject)

Return True if node is present in the graph.

has_edge

has_edge(
    source: OmkObject,
    target: OmkObject,
    edge_type: EdgeType | None = None,
)

Return True if an edge (optionally of the given type) exists from source to target.

num_nodes

num_nodes()

Return the total number of nodes in the graph.

num_edges

num_edges()

Return the total number of edges in the graph.

nodes

nodes(
    node_type: type[OmkObject] | None = None,
    predicate: Callable[[OmkObject], bool] | None = None,
)

Iterate over nodes, optionally filtered by node_type and/or predicate.

edges

edges(
    edge_type: EdgeType | None = None,
    predicate: Callable[[OmkEdge], bool] | None = None,
)

Iterate over edges, optionally filtered by edge_type and/or predicate.

edges_between

edges_between(
    source: OmkObject,
    target: OmkObject,
    edge_type: EdgeType | None = None,
)

Iterate over edges from source to target, optionally filtered by edge_type.

successors

successors(
    node: OmkObject,
    node_type: type[OmkObject] | None = None,
    edge_type: EdgeType | None = None,
    predicate: Callable[[OmkObject], bool] | None = None,
)

Iterate over nodes reachable from node via an outgoing edge, optionally filtered.

predecessors

predecessors(
    node: OmkObject,
    node_type: type[OmkObject] | None = None,
    edge_type: EdgeType | None = None,
    predicate: Callable[[OmkObject], bool] | None = None,
)

Iterate over nodes that have an outgoing edge to node, optionally filtered.

get_next

get_next(node: OmkObject)

Return the next node connected by an edge of type NEXT from the given node, if it exists.

get_previous

get_previous(node: OmkObject)

Return the previous node connected by an edge of type NEXT to the given node, if it exists.

neighbors

neighbors(
    node: OmkObject,
    node_type: type[OmkObject] | None = None,
    edge_type: EdgeType | None = None,
    predicate: Callable[[OmkObject], bool] | None = None,
)

Iterate over all nodes adjacent to node (predecessors and successors), optionally filtered.

out_edges

out_edges(node: OmkObject, edge_type: EdgeType | None = None)

Iterate over edges originating from node, optionally filtered by edge_type.

in_edges

in_edges(node: OmkObject, edge_type: EdgeType | None = None)

Iterate over edges terminating at node, optionally filtered by edge_type.

incident_edges

incident_edges(node: OmkObject, edge_type: EdgeType | None = None)

Iterate over all edges touching node (incoming and outgoing), optionally filtered by edge_type.

degree

degree(node: OmkObject)

Return the total number of edges incident to node.

in_degree

in_degree(node: OmkObject)

Return the number of edges terminating at node.

out_degree

out_degree(node: OmkObject)

Return the number of edges originating from node.