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Note

This documents the development version of NetworkX. Documentation for the current release can be found here.

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networkx.generators.interval_graph.interval_graph

interval_graph(intervals)

Generates an interval graph for a list of intervals given.

In graph theory, an interval graph is an undirected graph formed from a set of closed intervals on the real line, with a vertex for each interval and an edge between vertices whose intervals intersect. It is the intersection graph of the intervals.

More information can be found at: https://en.wikipedia.org/wiki/Interval_graph

Parameters

• intervals (a sequence of intervals, say (l, r) where l is the left end,)

• and r is the right end of the closed interval.

Returns

G

Return type

networkx graph

Examples

>>> intervals = [(-2, 3), [1, 4], (2, 3), (4, 6)]
>>> G = nx.interval_graph(intervals)
>>> sorted(G.edges)
[((-2, 3), (1, 4)), ((-2, 3), (2, 3)), ((1, 4), (2, 3)), ((1, 4), (4, 6))]

Raises

• TypeError – if intervals contains None or an element which is not collections.abc.Sequence or not a length of 2.

• ValueError – if intervals contains an interval such that min1 > max1 where min1,max1 = interval