如何用DataFrame列数据设置NetworkX节点颜色与大小并绘图？报错排查

问题场景 #

尝试使用NetworkX库，基于DataFrame的Source与Destination列构建边绘制网络图，同时用Circuit列设置节点颜色、Picklist列设置节点大小，运行时触发TypeError错误，报错信息如下：

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
~\AppData\Local\Temp\1\ipykernel_3332\2173665631.py in <module>
     45 
     46 fig = plt.figure()
---> 47 nx.draw_networkx(df, "Source", "Destination", node_color=node_color, node_size=node_size, font_color="whitesmoke")
     48 fig.set_facecolor('blue')
     49 plt.show()

~\Anaconda3\lib\site-packages\networkx\drawing\nx_pylab.py in draw_networkx(G, pos, arrows, with_labels, **kwds)
    301         pos = nx.drawing.spring_layout(G)  # default to spring layout
    302 
---> 303     draw_networkx_nodes(G, pos, **node_kwds)
    304     draw_networkx_edges(G, pos, arrows=arrows, **edge_kwds)
    305     if with_labels:

~\Anaconda3\lib\site-packages\networkx\drawing\nx_pylab.py in draw_networkx_nodes(G, pos, nodelist, node_size, node_color, node_shape, alpha, cmap, vmin, vmax, ax, linewidths, edgecolors, label, margins)
    423 
    424     try:
---> 425         xy = np.asarray([pos[v] for v in nodelist])
    426     except KeyError as err:
    427         raise nx.NetworkXError(f"Node {err} has no position.") from err

~\Anaconda3\lib\site-packages\networkx\drawing\nx_pylab.py in <listcomp>(.0)
    423 
    424     try:
---> 425         xy = np.asarray([pos[v] for v in nodelist])
    426     except KeyError as err:
    427         raise nx.NetworkXError(f"Node {err} has no position.") from err

TypeError: string indices must be integers

错误原因 #

1. 核心参数错误：nx.draw_networkx()的第一个参数必须是NetworkX的图对象（如nx.Graph()），你直接传入了DataFrame对象df，导致内部逻辑把字符串当作字典处理，触发"string indices must be integers"错误。
2. 图结构未正确构建：没有将DataFrame中的Source和Destination转换为图的边，图对象未正确初始化。
3. 节点属性关联错误：当前node_color和node_size是对列值去重后的列表，没有与实际节点一一对应，无法正确映射到每个节点。

修复后的代码 #

import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
import networkx as nx

import warnings
warnings.filterwarnings('ignore')

# 构造测试数据
data = [{'Circuit': 'html','Description':1, 'Duration':10.2, 'Source':'Westchester', 'Destination':'Davie', 'Picklist':1000, 'Postlist':50000.2}, 
       {'Circuit': 'html', 'Description':2, 'Duration':12.1, 'Source':'Westchester', 'Destination':'Davie', 'Picklist':3000, 'Postlist':40000.1},
       {'Circuit': 'html', 'Description':3, 'Duration':11.3, 'Source':'Westchester', 'Destination':'Davie', 'Picklist':7000, 'Postlist':50000.2}, 
       {'Circuit': 'html', 'Description':3, 'Duration':8.1, 'Source':'West', 'Destination':'San Bernardino', 'Picklist':3000, 'Postlist':40000.0},
       {'Circuit': '.net', 'Description':4, 'Duration':6.2, 'Source':'Queens', 'Destination':'San Bernardino', 'Picklist':5000, 'Postlist':6000.1}, 
       {'Circuit': '.net', 'Description':3, 'Duration':20.1, 'Source':'Queens', 'Destination':'Los Angeles', 'Picklist':5000, 'Postlist':4000.1},
       {'Circuit': '.net', 'Description':2, 'Duration':15.5, 'Source':'Brooklyn', 'Destination':'San Francisco', 'Picklist':5000, 'Postlist':9000.3},
       {'Circuit': '.net', 'Description':4, 'Duration':7.7, 'Source':'Brooklyn', 'Destination':'Davie', 'Picklist':6000, 'Postlist':10000},
       {'Circuit': '.net', 'Description':4, 'Duration':7.7, 'Source':'Los Angeles', 'Destination':'Westchester', 'Picklist':6000, 'Postlist':10000},
       {'Circuit': '.net', 'Description':4, 'Duration':7.7, 'Source':'San Berdarnino', 'Destination':'Westchester', 'Picklist':6000, 'Postlist':10000}]
df = pd.DataFrame(data)

# 1. 从DataFrame构建图结构，Source和Destination作为边的两端
G = nx.from_pandas_edgelist(df, source='Source', target='Destination')

# 2. 为节点添加属性：处理同一个节点多条记录的情况，取第一条的Circuit和Picklist值
node_attrs = {}
for _, row in df.iterrows():
    if row['Source'] not in node_attrs:
        node_attrs[row['Source']] = {'Circuit': row['Circuit'], 'Picklist': row['Picklist']}
    if row['Destination'] not in node_attrs:
        node_attrs[row['Destination']] = {'Circuit': row['Circuit'], 'Picklist': row['Picklist']}

# 将属性添加到图的节点中
nx.set_node_attributes(G, node_attrs)

# 3. 生成节点颜色和大小列表：与图中的节点顺序一一对应
color_map = {'html': 'red', '.net': 'blue'}
node_color = [color_map[G.nodes[node]['Circuit']] for node in G.nodes()]
# 缩小Picklist值比例，避免节点过大
node_size = [G.nodes[node]['Picklist'] * 0.1 for node in G.nodes()]

# 4. 绘制网络图
fig = plt.figure()
pos = nx.spring_layout(G)
nx.draw_networkx(G, pos=pos, node_color=node_color, node_size=node_size, font_color="whitesmoke")
fig.set_facecolor('blue')
plt.show()

关键修复点 #

• 用nx.from_pandas_edgelist()正确构建图的边关系
• 给每个节点关联对应的Circuit和Picklist属性，确保颜色和大小能正确映射到节点
• nx.draw_networkx()传入正确的图对象G，并使用布局函数生成节点位置pos

内容的提问来源于stack exchange，提问作者ASH