objectgraph  Reference documentation¶
A basic graph library
This package provides a class ObjectGraph that represents a basic graph where nodes are arbitrary objects with a stringvalues attribute named “identifier”.
Edges between nodes have arbrary (hashable) attributes, where edges with the same source, destination and attributes are collapsed into one edge.
Graph¶

class
objectgraph.
ObjectGraph
¶ A basic graph datastructure where the nodes can be arbitrary objects with an attribute named “identifier”. Edges between nodes can have associated data.
There can be multiple edges between nodes, but all edges with the same attributes are collapsed into one edge.
For Mypy users this is a generic class with two type parameters:
The node type
An arbitrary that that has an stringvalued attribute named “identifier”
The edge type
An arbirary type that is hashable.
Creating and updating a graph¶

ObjectGraph.
__init__
()¶ Create a new empty graph

ObjectGraph.
add_node
(node: NODE_TYPE) → None¶ Add a root to the graph
Parameters: node – A node

ObjectGraph.
add_root
(node: Union[str, NODE_TYPE]) → None¶ Add a root to the graph
Parameters: node – A node or name of a node. Raises: KeyError
– if the node is not part of the graph

ObjectGraph.
add_edge
(source: Union[str, NODE_TYPE], destination: Union[str, NODE_TYPE], edge_attributes: EDGE_TYPE) → None¶ Add a directed edge between source and destination with edge attributes. Edges between the source and destination with the same edge attributes are merged into a single edge.
Parameters:  source – A node or node identifier
 destination – A node or node identifier
 edge_attributes – Attributes for the edge, must be hashable
Raises: KeyError
– If the source or destination are not nodes in the graph

ObjectGraph.
remove_edge
(source: Union[str, NODE_TYPE], destination: Union[str, NODE_TYPE], edge_attributes: EDGE_TYPE) → None¶ Remove an edge from the graph
Parameters:  source – a node or node identifier
 destination – a node or node identifier
 edge_attributes – attributes of the edge that should be removed
Raises:

ObjectGraph.
remove_all_edges
(source: Union[str, NODE_TYPE], destination: Union[str, NODE_TYPE])¶ Remove all edges between source and destination.
Parameters:  source – a node or node identifier
 destination – a node or node identifier
Raises: KeyError
– If the source of destination are not found
Reporting on a graph¶

ObjectGraph.
find_node
(node: Union[str, NODE_TYPE]) → Optional[NODE_TYPE]¶ Find a node in the graph. If the argument is a node object this looks for a graph member with the same identifier.
Parameters: node – A node or node identifier Returns: The node found, or None
when the node is not present

ObjectGraph.
__contains__
(node: Union[str, NODE_TYPE])¶ Check if a node is a member of the graph
Parameters: node – The node or node identifier to look for Returns: True if the node is part of the graph, False otherwise

ObjectGraph.
edge_data
(source: Union[str, NODE_TYPE], destination: Union[str, NODE_TYPE]) → Set[EDGE_TYPE]¶ Return the all edge attributes for edges between source and destination.
Parameters:  source – A node or node identifier
 destination – A node or node identifier
Returns: A set of edge attributes for all edges between source and destination
Raises:

ObjectGraph.
roots
() → Iterator[NODE_TYPE]¶ Yield the roots of the graph in an arbirary order.

ObjectGraph.
nodes
() → Iterator[NODE_TYPE]¶ Yield all nodes in the graph in an arbirary order.

ObjectGraph.
iter_graph
(*, node: Union[str, NODE_TYPE] = None, _visited: Optional[set] = None) → Iterator[NODE_TYPE]¶ Yield all nodes in the graph reachable from node or any of the graph roots.
Parameters: node – The node or node identifier used to start iterating. Defaults to using the graph roots.

ObjectGraph.
edges
() → Iterator[Tuple[NODE_TYPE, NODE_TYPE, Set[EDGE_TYPE]]]¶ Yield the source and destination of all edges in the graph with a set of all unique edge attributes for edges between the two nodes.

ObjectGraph.
incoming
(destination: Union[str, NODE_TYPE]) → Iterator[Tuple[Set[EDGE_TYPE], NODE_TYPE]]¶ Yield (edge, node) for all incoming edges
Parameters: destination – A node or node identifier

ObjectGraph.
outgoing
(source: Union[str, NODE_TYPE]) → Iterator[Tuple[Set[EDGE_TYPE], NODE_TYPE]]¶ Yield (edge, node) for all outgoing edges
Parameters: source – A node or node identifier