问题描述
因此,我在使用此python脚本时遇到了错误,我是python的新手,也许犯了一个愚蠢的错误,请帮帮我。
import networkx as nx
import matplotlib.pyplot as plt
import random
G=nx.Graph()
city_set=['Ranchi','Delhi','Mumbai','Kolkata','Jaipur','Pune','Surat','Chennai']
for each in city_set:
G.add_node(each)
# nx.draw(G,with_labels=1)
# plt.show()
#print(G.nodes())
# name=random.choice(list(G.nodes()))
# print(name)
# Adding edges
costs=[]
value=100
while(value<2000):
costs.append(value)
value+=100
while(G.number_of_edges()<16):
c1=random.choice(G.nodes())
c2=random.choice(G.nodes())
if (c1!=c2)and (G.has_edge(c1,c2))==0:
w=random.choice(costs)
G.add_edge(c1,c2,weight=w)
nx.draw(G,with_labels=1)
plt.show()
我得到的错误是:-
KeyError Traceback (most recent call last)
<ipython-input-29-67a2861315c5> in <module>
13 print(G.nodes())
14
---> 15 name=random.choice(list(G.nodes()))
16 print(name)
17
D:\ANACONDA\lib\random.py in choice(self,seq)
260 except ValueError:
261 raise IndexError('Cannot choose from an empty sequence') from None
--> 262 return seq[i]
263
264 def shuffle(self,x,random=None):
D:\ANACONDA\lib\site-packages\networkx\classes\reportviews.py in __getitem__(self,n)
275
276 def __getitem__(self,n):
--> 277 ddict = self._nodes[n]
278 data = self._data
279 if data is False or data is True:
KeyError: 2
解决方法
G.nodes()
返回一个NodeView对象,该对象是一个字典类型,其中包含每个节点的数据。如文档中所述:
“如果不需要您的节点数据,则将表达式用于G中的n或list(G)更为简单和等效。”
使用强制转换为G.nodes()上的列表: 固定:
import networkx as nx
import matplotlib.pyplot as plt
import random
G=nx.Graph()
city_set=['Ranchi','Delhi','Mumbai','Kolkata','Jaipur','Pune','Surat','Chennai']
for each in city_set:
G.add_node(each)
# nx.draw(G,with_labels=1)
# plt.show()
#print(G.nodes())
# name=random.choice(list(G.nodes()))
# print(name)
# Adding edges
costs=[]
value=100
while(value<2000):
costs.append(value)
value+=100
while(G.number_of_edges()<16):
c1=random.choice(list(G.nodes()))
c2=random.choice(list(G.nodes()))
if (c1!=c2)and (G.has_edge(c1,c2))==0:
w=random.choice(costs)
G.add_edge(c1,c2,weight=w)
nx.draw(G,with_labels=1)
plt.show()
,
G.nodes()
返回一个NodeView
,并且当随机函数尝试通过其索引选择元素时,它会失败,因为找不到它。
解决方案可能包括在代码中使用list(G.nodes())
。
更好的选择是使用random.sample直接选择2个元素,而不是一次选择一个,然后检查它们是否相同。
G.add_nodes_from(city_set)
costs = list(range(100,2000,100))
while(G.number_of_edges() < 16):
c1,c2 = random.sample(city_set,2)
if not G.has_edge(c1,c2):
w = random.choice(costs)
G.add_edge(c1,weight=w)