Pygraphviz / networkx 设置节点层级或层次
我有一个数据集，表示一种家谱树。每个节点都有两个父母（除了第一代，它们没有父母）。对于一个给定的节点，它的父母可以来自任何之前的世代。比如说，一个在第n代的节点，可以有一个父母在n-1代，另一个父母在n-5代。一个节点可以是多个其他节点的父母。
所以基本上，对于每个节点，我知道它的世代和它的父母。
我正在尝试表示这个图形，保持同一世代的节点在同一行。每一代有10个节点，除了第一代。
到目前为止，我尝试使用“dot”布局。当我只输入两代时，它表现得很好，但当我输入三代时，它就“太聪明”了，以某种方式重新排列节点。
例如，以下数据表示三代：
[(ObjectId('530b2ad783a1a15e695c9711'), ObjectId('530b804883a1a15e695c972b')), (ObjectId('530b2ad783a1a15e695c971c'), ObjectId('530b804883a1a15e695c972b')), (ObjectId('530b2ad783a1a15e695c9709'), ObjectId('530b804883a1a15e695c9727')), (ObjectId('530b2ad783a1a15e695c970a'), ObjectId('530b804883a1a15e695c9727')), (ObjectId('530b2ad783a1a15e695c970b'), ObjectId('530b804883a1a15e695c9724')), (ObjectId('530b2ad783a1a15e695c970f'), ObjectId('530b804883a1a15e695c9724')), (ObjectId('530b2ad783a1a15e695c9714'), ObjectId('530b804883a1a15e695c9729')), (ObjectId('530b2ad783a1a15e695c970e'), ObjectId('530b804883a1a15e695c9729')), (ObjectId('530b2ad783a1a15e695c9711'), ObjectId('530b804883a1a15e695c9723')), (ObjectId('530b2ad783a1a15e695c970e'), ObjectId('530b804883a1a15e695c9723')), (ObjectId('530b2ad783a1a15e695c971c'), ObjectId('530b804883a1a15e695c9728')), (ObjectId('530b2ad783a1a15e695c9719'), ObjectId('530b804883a1a15e695c9728')), (ObjectId('530b2ad783a1a15e695c9714'), ObjectId('530b804883a1a15e695c9726')), (ObjectId('530b2ad783a1a15e695c9713'), ObjectId('530b804883a1a15e695c9726')), (ObjectId('530b2ad783a1a15e695c9716'), ObjectId('530b804883a1a15e695c9722')), (ObjectId('530b2ad783a1a15e695c9719'), ObjectId('530b804883a1a15e695c9722')), (ObjectId('530b2ad783a1a15e695c970d'), ObjectId('530b804883a1a15e695c9725')), (ObjectId('530b2ad783a1a15e695c9715'), ObjectId('530b804883a1a15e695c9725')), (ObjectId('530b804883a1a15e695c9724'), ObjectId('530ba27c83a1a15e695c972d')), (ObjectId('530b2ad783a1a15e695c9713'), ObjectId('530ba27c83a1a15e695c972d')), (ObjectId('530b804883a1a15e695c9724'), ObjectId('530ba27c83a1a15e695c972e')), (ObjectId('530b2ad783a1a15e695c9709'), ObjectId('530ba27c83a1a15e695c972e')), (ObjectId('530b804883a1a15e695c9727'), ObjectId('530ba27c83a1a15e695c972f')), (ObjectId('530b2ad783a1a15e695c9709'), ObjectId('530ba27c83a1a15e695c972f')), (ObjectId('530b2ad783a1a15e695c9713'), ObjectId('530ba27c83a1a15e695c9730')), (ObjectId('530b2ad783a1a15e695c9709'), ObjectId('530ba27c83a1a15e695c9730')), (ObjectId('530b2ad783a1a15e695c9713'), ObjectId('530ba27c83a1a15e695c9731')), (ObjectId('530b804883a1a15e695c9725'), ObjectId('530ba27c83a1a15e695c9731')), (ObjectId('530b804883a1a15e695c9722'), ObjectId('530ba27c83a1a15e695c9732')), (ObjectId('530b2ad783a1a15e695c970b'), ObjectId('530ba27c83a1a15e695c9732')), (ObjectId('530b2ad783a1a15e695c9711'), ObjectId('530ba27c83a1a15e695c9733')), (ObjectId('530b2ad783a1a15e695c971f'), ObjectId('530ba27c83a1a15e695c9733')), (ObjectId('530b804883a1a15e695c972b'), ObjectId('530ba27c83a1a15e695c9734')), (ObjectId('530b2ad783a1a15e695c9713'), ObjectId('530ba27c83a1a15e695c9734')), (ObjectId('530b2ad783a1a15e695c9709'), ObjectId('530ba27c83a1a15e695c9735')), (ObjectId('530b804883a1a15e695c9724'), ObjectId('530ba27c83a1a15e695c9735')), (ObjectId('530b2ad783a1a15e695c9713'), ObjectId('530ba27c83a1a15e695c9736')), (ObjectId('530b804883a1a15e695c9723'), ObjectId('530ba27c83a1a15e695c9736')), (ObjectId('530b2ad783a1a15e695c9716'), ObjectId('530b804883a1a15e695c9722')), (ObjectId('530b2ad783a1a15e695c9719'), ObjectId('530b804883a1a15e695c9722')), (ObjectId('530b2ad783a1a15e695c9711'), ObjectId('530b804883a1a15e695c9723')), (ObjectId('530b2ad783a1a15e695c970e'), ObjectId('530b804883a1a15e695c9723')), (ObjectId('530b2ad783a1a15e695c970b'), ObjectId('530b804883a1a15e695c9724')), (ObjectId('530b2ad783a1a15e695c970f'), ObjectId('530b804883a1a15e695c9724')), (ObjectId('530b2ad783a1a15e695c970d'), ObjectId('530b804883a1a15e695c9725')), (ObjectId('530b2ad783a1a15e695c9715'), ObjectId('530b804883a1a15e695c9725')), (ObjectId('530b2ad783a1a15e695c9714'), ObjectId('530b804883a1a15e695c9726')), (ObjectId('530b2ad783a1a15e695c9713'), ObjectId('530b804883a1a15e695c9726')), (ObjectId('530b2ad783a1a15e695c9709'), ObjectId('530b804883a1a15e695c9727')), (ObjectId('530b2ad783a1a15e695c970a'), ObjectId('530b804883a1a15e695c9727')), (ObjectId('530b2ad783a1a15e695c971c'), ObjectId('530b804883a1a15e695c9728')), (ObjectId('530b2ad783a1a15e695c9719'), ObjectId('530b804883a1a15e695c9728')), (ObjectId('530b2ad783a1a15e695c9714'), ObjectId('530b804883a1a15e695c9729')), (ObjectId('530b2ad783a1a15e695c970e'), ObjectId('530b804883a1a15e695c9729')), (ObjectId('530b2ad783a1a15e695c9715'), ObjectId('530b804883a1a15e695c972a')), (ObjectId('530b2ad783a1a15e695c970b'), ObjectId('530b804883a1a15e695c972a')), (ObjectId('530b2ad783a1a15e695c9711'), ObjectId('530b804883a1a15e695c972b')), (ObjectId('530b2ad783a1a15e695c971c'), ObjectId('530b804883a1a15e695c972b'))]
生成的结果是：
所有的“根”节点，也就是没有接收到边的节点，应该放在第一行，比如说，但它却把其中一些放在第二层。
一旦我尝试制作更大的图，像10代那样，所有的层级就完全没有意义了。
有没有什么参数或者方法可以指定一个节点的层级？在我提供的数据中没有这个信息，但我可以很容易地生成它，问题是我不知道如何将这些信息发送给pygraphviz或networkx。
我还想用这些数据生成像这样的图，使用twopi布局 http://networkx.github.io/documentation/latest/examples/drawing/lanl_routes.html
在这个布局中，层级是以圆形的方式表示的。
3 个回答
这个链接会对你有帮助。rank_same.py
import graphviz
d = graphviz.Digraph(filename='rank_same.gv')
with d.subgraph() as s:
s.attr(rank='same')
s.node('A')
s.node('X')
d.node('C')
with d.subgraph() as s:
s.attr(rank='same')
s.node('B')
s.node('D')
s.node('Y')
d.edges(['AB', 'AC', 'CD', 'XY'])
d.view()
从2017年开始，to_agraph这个功能不再直接在nx.level里面使用了。现在你需要用nx.nx_agraph.to_agraph()来调用它。
使用Graphviz的子图，并设置属性rank=same。这个设置可以让你在图中把某些节点放在同一水平线上，保持它们的对齐。比如：
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')
