Python网络在使用draw_network_nodes()时如何改变节点颜色？

Question

目标是得到一个类似于下面的效果：

为了定义这个图形，我使用了：

import matplotlib.pyplot as plt
import networkx as nx
graph = {
    '1': ['2', '3', '4'],
    '2': ['5','11','12','13','14','15'],
    '3' : ['6','7','66','77'],
    '5': ['6', '8','66','77'],
    '4': ['7','66','77'],
    '7': ['9', '10']
    } 

MG = nx.DiGraph()
MG.add_edges_from([(start, stop, {'weigth' :  len(graph[start]) }) 
     for start in graph for stop in graph[start]])

而绘制这个图形的代码是：

plt.figure(figsize=(8,8))
pos=nx.graphviz_layout(MG,prog="twopi",root='1')
for n in MG.nodes_iter():
    nx.draw_networkx_nodes(MG, pos,
        nodelist = [n],
        node_size = 2000 / float(len(MG[n[0]])+1),
        node_color = (len(MG[n[0]])+1),
        alpha = 1/float(len(MG[n[0]])+1),
        with_labels=True
                       )
xmax=1.1*max(xx for xx,yy in pos.values())
ymax=1.1*max(yy for xx,yy in pos.values())
plt.xlim(0,xmax)
plt.ylim(0,ymax)
plt.show()

这里有两件事我想了解：

• 我怎么才能让节点的颜色根据每个节点的连接数量来变化（也就是 len(MG[0])）？

• 我的标签在哪里？

谢谢

Answer 1

这样怎么样？你可以使用matplotlib的颜色映射功能，把数值转换成节点的颜色。

import matplotlib.pyplot as plt
import networkx as nx
graph = {
    '1': ['2', '3', '4'],
    '2': ['5','11','12','13','14','15'],
    '3' : ['6','7','66','77'],
    '5': ['6', '8','66','77'],
    '4': ['7','66','77'],
    '7': ['9', '10']
    }

MG = nx.DiGraph(graph)


plt.figure(figsize=(8,8))
pos=nx.graphviz_layout(MG,prog="twopi",root='1')

nodes = MG.nodes()
degree = MG.degree()
color = [degree[n] for n in nodes]
size = [2000 / (degree[n]+1.0) for n in nodes]

nx.draw(MG, pos, nodelist=nodes, node_color=color, node_size=size,
        with_labels=True, cmap=plt.cm.Blues, arrows=False)
plt.show()