PyGraph

class PyGraph(multigraph=True, attrs=None, *, node_count_hint=None, edge_count_hint=None)

Bases: object

A class for creating undirected graphs

The PyGraph class is used to create an undirected graph. It can be a multigraph (have multiple edges between nodes). Each node and edge (although rarely used for edges) is indexed by an integer id. These ids are stable for the lifetime of the graph object and on node or edge deletions you can have holes in the list of indices for the graph. Node indices will be reused on additions after removal. For example:

import rustworkx as rx

graph = rx.PyGraph()
graph.add_nodes_from(list(range(5)))
graph.add_nodes_from(list(range(2)))
graph.remove_node(2)
print("After deletion:", graph.node_indices())
res_manual = graph.add_node(None)
print("After adding a new node:", graph.node_indices())

After deletion: NodeIndices[0, 1, 3, 4, 5, 6]
After adding a new node: NodeIndices[0, 1, 2, 3, 4, 5, 6]

Additionally, each node and edge contains an arbitrary Python object as a weight/data payload. You can use the index for access to the data payload as in the following example:

import rustworkx as rx

graph = rx.PyGraph()
data_payload = "An arbitrary Python object"
node_index = graph.add_node(data_payload)
print("Node Index: %s" % node_index)
print(graph[node_index])

Node Index: 0
An arbitrary Python object

The PyGraph implements the Python mapping protocol for nodes so in addition to access you can also update the data payload with:

import rustworkx as rx

graph = rx.PyGraph()
data_payload = "An arbitrary Python object"
node_index = graph.add_node(data_payload)
graph[node_index] = "New Payload"
print("Node Index: %s" % node_index)
print(graph[node_index])

Node Index: 0
New Payload

By default a PyGraph is a multigraph (meaning there can be parallel edges between nodes) however this can be disabled by setting the multigraph kwarg to False when calling the PyGraph constructor. For example:

import rustworkx as rx
graph = rx.PyGraph(multigraph=False)

This can only be set at PyGraph initialization and not adjusted after creation. When multigraph is set to False if a method call is made that would add a parallel edge it will instead update the existing edge’s weight/data payload.

Each PyGraph object has an attrs attribute which is used to contain additional attributes/metadata of the graph instance. By default this is set to None but can optionally be specified by using the attrs keyword argument when constructing a new graph:

graph = rustworkx.PyGraph(attrs=dict(source_path='/tmp/graph.csv'))

This attribute can be set to any Python object. Additionally, you can access and modify this attribute after creating an object. For example:

source_path = graph.attrs
graph.attrs = {'new_path': '/tmp/new.csv', 'old_path': source_path}

The maximum number of nodes and edges allowed on a PyGraph object is \(2^{32} - 1\) (4,294,967,294) each. Attempting to add more nodes or edges than this will result in an exception being raised.

Parameters:

• multigraph (bool) – When this is set to False the created PyGraph object will not be a multigraph. When False if a method call is made that would add parallel edges the weight/weight from that method call will be used to update the existing edge in place.

• attrs (Any) – An optional attributes payload to assign to the attrs attribute. This can be any Python object. If it is not specified attrs will be set to None.

• node_count_hint (int) – An optional hint that will allocate enough capacity to store this many nodes before needing to grow. This does not prepopulate any nodes with data, it is only a potential performance optimization if the complete size of the graph is known in advance.

• edge_count_hint (int) – An optional hint that will allocate enough capacity to store this many edges before needing to grow. This does not prepopulate any edges with data, it is only a potential performance optimization if the complete size of the graph is known in advance.

Methods

add_edge	Add an edge between 2 nodes.
add_edges_from	Add new edges to the graph.
add_edges_from_no_data	Add new edges to the graph without python data.
add_node	Add a new node to the graph.
add_nodes_from	Add new nodes to the graph.
adj	Get the index and data for the neighbors of a node.
clear	Clears all nodes and edges
clear_edges	Clears all edges, leaves nodes intact
compose	Add another PyGraph object into this PyGraph
contract_nodes	Substitute a set of nodes with a single new node.
copy	Return a shallow copy of the graph
degree	Get the degree for a node
edge_index_map	Get an edge index map
edge_indices	Return a list of all edge indices.
edge_indices_from_endpoints	Return a list of indices of all edges between specified nodes
edge_list	Get edge list
edge_subgraph	Return a new PyGraph object for an edge induced subgraph of this graph
edges	Return a list of all edge data.
extend_from_edge_list	Extend graph from an edge list
extend_from_weighted_edge_list	Extend graph from a weighted edge list
filter_edges	Filters a graph's edges by some criteria conditioned on a edge's data payload and returns those edges' indices.
filter_nodes	Filters a graph's nodes by some criteria conditioned on a node's data payload and returns those nodes' indices.
find_node_by_weight	Find node within this graph given a specific weight
from_adjacency_matrix	Create a new PyGraph object from an adjacency matrix with matrix elements of type float
from_complex_adjacency_matrix	Create a new PyGraph object from an adjacency matrix with matrix elements of type complex
get_all_edge_data	Return the edge data for all the edges between 2 nodes.
get_edge_data	Return the edge data for the edge between 2 nodes.
get_edge_data_by_index	Return the edge data for the edge by its given index
get_edge_endpoints_by_index	Return the edge endpoints for the edge by its given index
get_node_data	Return the node data for a given node index
has_edge	Check if there is any undirected edge between node_a and node_b.
has_node	Check if the node exists in the graph.
has_parallel_edges	Detect if the graph has parallel edges or not
in_edge_indices	Return the list of edge indices incident to a provided node.
in_edges	Get the endpoint indices and edge data for all edges of a node.
incident_edge_index_map	Return the index map of edges incident to a provided node
incident_edges	Return the list of edge indices incident to a provided node
neighbors	Get the neighbors of a node.
node_indexes	Return a list of all node indices.
node_indices	Return a list of all node indices.
nodes	Return a list of all node data.
num_edges	Return the number of edges in the graph
num_nodes	Return the number of nodes in the graph
out_edge_indices	Return the list of edge indices incident to a provided node.
out_edges	Get the endpoint indices and edge data for all edges of a node.
read_edge_list	Read an edge list file and create a new PyGraph object from the contents
remove_edge	Remove an edge between 2 nodes.
remove_edge_from_index	Remove an edge identified by the provided index
remove_edges_from	Remove edges from the graph.
remove_node	Remove a node from the graph.
remove_nodes_from	Remove nodes from the graph.
subgraph	Return a new PyGraph object for a subgraph of this graph.
subgraph_with_nodemap	Return a new PyGraph object for a subgraph of this graph and a NodeMap object that maps the nodes of the subgraph to the nodes of the original graph.
substitute_node_with_subgraph	substitute_node_with_subgraph(self, node, other, edge_map_fn, /, node_filter=None, edge_weight_map=None
to_directed	Generate a new PyDiGraph object from this graph
to_dot	Generate a dot file from the graph
update_edge	Update an edge's weight/payload in place
update_edge_by_index	Update an edge's weight/data payload in place by the edge index
weighted_edge_list	Get edge list with weights
write_edge_list	Write an edge list file from the PyGraph object

Attributes

attrs

multigraph

Whether the graph is a multigraph (allows multiple edges between nodes) or not

If set to False multiple edges between nodes are not allowed and calls that would add a parallel edge will instead update the existing edge