PyGraph#

class PyGraph#

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 the weight/weight from that method call will be used to update the existing edge in place.
attrs – 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`	Return True if there is an edge between `node_a` and `node_b`.
`has_node`	Return True if there is a node.
`has_parallel_edges`	Detect if the graph has parallel edges or not
`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_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
`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