python—networkx：求图的平均路径长度并画出直方图

要绘制一个动态网络，到处找资料，收集相关的networkx绘图资料，计算路径的代码如下：

NetworkX Examples—BASIC——properties

#!/usr/bin/env python
"""
Compute some network properties for the lollipop graph.
"""
#    Copyright (C) 2004 by
#    Aric Hagberg 
#    Dan Schult 
#    Pieter Swart 
#    All rights reserved.
#    BSD license.

from networkx import *
G = lollipop_graph(4,6)
pathlengths=[]
#单源最短路径算法求出节点v到图G每个节点的最短路径，存入pathlengths

print("source vertex {target:length, }")
for v in G.nodes():
    spl=single_source_shortest_path_length(G,v)
    print('%s %s' % (v,spl))
    for p in spl.values():
        pathlengths.append(p)
#取出每条路径，计算平均值。
print('')print("average shortest path length %s" % (sum(pathlengths)/len(pathlengths)))
#路径长度直方图，如果路径不存在，设为1，如果已经存在过一次，则原先基础上加1
# histogram of path lengths
dist={}
for p in pathlengths:
    if p in dist:
        dist[p]+=1
    else:
        dist[p]=1

print('')
print("length #paths")
verts=dist.keys()
for d in sorted(verts):
    print('%s %d' % (d,dist[d]))
#内嵌函数求图G的多个属性
print("radius: %d" % radius(G))
print("diameter: %d" % diameter(G))
print("eccentricity: %s" % eccentricity(G))
print("center: %s" % center(G))
print("periphery: %s" % periphery(G))
print("density: %s" % density(G))