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