Pygraphviz / networkx set node level or layer

Question

I have a dataset that represents a kind of genealogy tree. Each node has 2 parents (except first generation, they have no parents). For a given node, its parents can be from

Answer 1

As of 2017, the function to_agraph is no longer exposed at the nx.level. Now you must call nx.nx_agraph.to_agraph()

Answer 2

Use a Graphviz subgraph with attribute rank=same. e.g.

import networkx as nx
import pygraphviz as pgv # pygraphviz should be available

G = nx.DiGraph()
G.add_edge('a','aa')
G.add_edge('a','ab')
G.add_edge('a','bbc')
G.add_edge('b','ab')
G.add_edge('b','bb')
G.add_edge('c','bbc')
G.add_edge('bb','bba')
G.add_edge('bb','bbc')
A = nx.to_agraph(G)
one = A.add_subgraph(['a','b','c'],rank='same')
two = A.add_subgraph(['aa','ab','bb'],rank='same')
three = A.add_subgraph(['bba','bbc'],rank='same')
A.draw('example.png', prog='dot')