Impulse Graph¶

Overview¶

class dynetworkx.ImpulseGraph(name='', **attr)¶

Base class for undirected interval graphs.

The ImpulseGraph class allows any hashable object as a node and can associate key/value attribute pairs with each undirected edge.

Each edge must have one integer, timestamp.

Self-loops are allowed. Multiple edges between two nodes are allowed.

Parameters:	attr (keyword arguments, optional (default= no attributes)) – Attributes to add to graph as key=value pairs.

Examples

Create an empty graph structure (a “null interval graph”) with no nodes and no edges.

>>> G = dnx.ImpulseGraph()

G can be grown in several ways.

Nodes:

Add one node at a time:

>>> G.add_node(1)

Add the nodes from any container (a list, dict, set or even the lines from a file or the nodes from another graph).

Add the nodes from any container (a list, dict, set)

>>> G.add_nodes_from([2, 3])
>>> G.add_nodes_from(range(100, 110))

Edges:

G can also be grown by adding edges. This can be considered the primary way to grow G, since nodes with no edge will not appear in G in most cases. See G.to_snapshot().

Add one edge, with timestamp of 10.

>>> G.add_edge(1, 2, 10)

a list of edges,

>>> G.add_edges_from([(1, 2, 10), (1, 3, 11)])

If some edges connect nodes not yet in the graph, the nodes are added automatically. There are no errors when adding nodes or edges that already exist.

Attributes:

Each impulse graph, node, and edge can hold key/value attribute pairs in an associated attribute dictionary (the keys must be hashable). By default these are empty, but can be added or changed using add_edge, add_node.

Keep in mind that the edge timestamp is not an attribute of the edge.

>>> G = dnx.IntervalGraph(day="Friday")
>>> G.graph
{'day': 'Friday'}

Add node attributes using add_node(), add_nodes_from()

>>> G.add_node(1, time='5pm')
>>> G.add_nodes_from([3], time='2pm')

Add edge attributes using add_edge(), add_edges_from().

>>> G.add_edge(1, 2, 10, weight=4.7 )
>>> G.add_edges_from([(3, 4, 11), (4, 5, 33)], color='red')

Shortcuts:

Here are a couple examples of available shortcuts:

>>> 1 in G  # check if node in impulse graph during any timestamp
True
>>> len(G)  # number of nodes in the entire impulse graph
5

Subclasses (Advanced): Edges in impulse graphs are represented by tuples kept in a SortedDict (http://www.grantjenks.com/docs/sortedcontainers/) keyed by timestamp.

The Graph class uses a dict-of-dict-of-dict data structure. The outer dict (node_dict) holds adjacency information keyed by nodes. The next dict (adjlist_dict) represents the adjacency information and holds edge data keyed by interval objects. The inner dict (edge_attr_dict) represents the edge data and holds edge attribute values keyed by attribute names.

Methods¶

Adding and removing nodes and edges¶

`ImpulseGraph.__init__`([name])	Initialize an interval graph with edges, name, or graph attributes.
`ImpulseGraph.add_node`(node_for_adding, **attr)	Add a single node node_for_adding and update node attributes.
`ImpulseGraph.add_nodes_from`(…)	Add multiple nodes.
`ImpulseGraph.remove_node`(n[, begin, end, …])	Remove the presence of a node n within the given interval.
`ImpulseGraph.add_edge`(u, v, t, **attr)	Add an edge between u and v, at t.
`ImpulseGraph.add_edges_from`(ebunch_to_add, …)	Add all the edges in ebunch_to_add.
`ImpulseGraph.remove_edge`(u, v[, begin, end, …])	Remove the edge between u and v in the impulse graph, during the given interval.

Reporting impulse graph, nodes and edges¶

`ImpulseGraph.nodes`([begin, end, inclusive, …])	A NodeDataView of the ImpulseGraph nodes.
`ImpulseGraph.has_node`(n[, begin, end, inclusive])	Return True if the impulse graph contains the node n, during the given interval.
`ImpulseGraph.edges`([u, v, begin, end, …])	Returns a list of Interval objects of the IntervalGraph edges.
`ImpulseGraph.has_edge`(u, v[, begin, end, …])	Return True if there exists an edge between u and v in the impulse graph, during the given interval.
`ImpulseGraph.__contains__`(n)	Return True if n is a node, False otherwise.
`ImpulseGraph.__str__`()	Return the interval graph name.
`ImpulseGraph.interval`()	Return a 2-tuple as (begin, end) interval of the entire

Counting nodes and edges¶

`ImpulseGraph.number_of_nodes`([begin, end, …])	Return the number of nodes in the impulse graph between the given interval.
`ImpulseGraph.__len__`()	Return the number of nodes.

Making copies and subgraphs¶

`ImpulseGraph.to_subgraph`(begin, end[, …])	Return a networkx Graph or MultiGraph which includes all the nodes and edges which have timestamps within the given interval.
`ImpulseGraph.to_snapshots`(number_of_snapshots)	Return a list of networkx Graph or MultiGraph objects as snapshots of the impulse graph in consecutive order.

Loading an impulse graph¶

`ImpulseGraph.load_from_txt`(path[, …])	Read impulse graph in from path.
`ImpulseGraph.save_to_txt`(path[, delimiter])	Write impulse graph to path.

Analyzing impulse graphs¶

ImpulseGraph.degree([node, begin, end, delta]) Return the degree of a specified node between time begin and end.