random_lobster

random_lobster(n, p1, p2, seed=None, *, create_using=None)

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:

nint

The expected number of nodes in the backbone

p1float

Probability of adding an edge to the backbone

p2float

Probability of adding an edge one level beyond backbone

seedinteger, random_state, or None (default)

Indicator of random number generation state. See Randomness.

create_usingGraph constructor, optional (default=nx.Grap)

Graph type to create. If graph instance, then cleared before populated. Multigraph and directed types are not supported and raise a NetworkXError.

Raises:

NetworkXError

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