python - Matplotlib 和 Networkx - 绘制自循环节点

Question

我有这个功能，我想画一个自循环。我该怎么做？
边缘存在，但我认为这只是这个例子中的一个点是 (1,1)，我无法添加节点的名称。我的目标是从邻接矩阵画出一个图。有没有更好的方法来做到这一点？

import networkx as nx
import matplotlib.pyplot as plt
from matplotlib.patches import FancyArrowPatch, Circle
import numpy as np

def draw_network(G,pos,ax,sg=None):

    for n in G:
        c=Circle(pos[n],radius=0.05,alpha=0.7)
        ax.add_patch(c)
        G.node[n]['patch']=c
        x,y=pos[n]
    seen={}
    for (u,v,d) in G.edges(data=True):
        n1=G.node[u]['patch']
        n2=G.node[v]['patch']
        rad=0.1
        if (u,v) in seen:
            rad=seen.get((u,v))
            rad=(rad+np.sign(rad)*0.1)*-1
        alpha=0.5
        color='k'

        e = FancyArrowPatch(n1.center,n2.center,patchA=n1,patchB=n2,
                            arrowstyle='-|>',
                            connectionstyle='arc3,rad=%s'%rad,
                            mutation_scale=10.0,
                            lw=2,
                            alpha=alpha,
                            color=color)
        seen[(u,v)]=rad
        ax.add_patch(e)
    return e


G=nx.MultiDiGraph([(1,2),(1,1),(1,2),(2,3),(3,4),(2,4),
                (1,2),(1,2),(1,2),(2,3),(3,4),(2,4)]
                )

pos=nx.spring_layout(G)
ax=plt.gca()
draw_network(G,pos,ax)
ax.autoscale()
plt.axis('equal')
plt.axis('off')

plt.show()

Answer 1

看来您的方法使用 matplotlib 相当先进，但我仍然建议使用专门的绘图库 (as does the networkx documentation)。随着图变得越来越大，出现了更多的问题——但这些库中已经解决的问题。

“转到”选项是 graphviz ，它可以很好地处理绘制多图。您可以从 networkx 图形编写点文件，然后使用图形绘制工具之一(例如 dot、neato 等)。

这是一个基于 graph attributes 的示例和 multigraph edge attributes :

import networkx as nx
from networkx.drawing.nx_agraph import to_agraph 

# define the graph as per your question
G=nx.MultiDiGraph([(1,2),(1,1),(1,2),(2,3),(3,4),(2,4), 
    (1,2),(1,2),(1,2),(2,3),(3,4),(2,4)])

# add graphviz layout options (see https://stackoverflow.com/a/39662097)
G.graph['edge'] = {'arrowsize': '0.6', 'splines': 'curved'}
G.graph['graph'] = {'scale': '3'}
                                                                                
# adding attributes to edges in multigraphs is more complicated but see
# https://stackoverflow.com/a/26694158                    
G[1][1][0]['color']='red'
                                                                                
A = to_agraph(G) 
A.layout('dot')                                                                 
A.draw('multi.png')   

请注意，您还可以轻松地从 ipython shell 中调用绘图: https://stackoverflow.com/a/14945560