networkx.generators.random_graphs.random_lobster

random_lobster(n, p1, p2, seed=None)[source]

Returns a random lobster graph.

A lobster is a tree that reduces to a caterpillar when pruning all leaf nodes. A caterpillar is a tree that reduces to a path graph when pruning all leaf nodes; setting p2 to zero produces a caterpillar.

This implementation iterates on the probabilities p1 and p2 to add edges at levels 1 and 2, respectively. Graphs are therefore constructed iteratively with uniform randomness at each level rather than being selected uniformly at random from the set of all possible lobsters.

Parameters

  • n (int) – The expected number of nodes in the backbone

  • p1 (float) – Probability of adding an edge to the backbone

  • p2 (float) – Probability of adding an edge one level beyond backbone

  • seed (integer, random_state, or None (default)) – Indicator of random number generation state. See Randomness.

Raises

NetworkXError – If p1 or p2 parameters are >= 1 because the while loops would never finish.