无法在Bokeh中使用HoverTool显示NetworkX中的标签

import networkx as nx
import pandas as pd
from bokeh.io import show
from bokeh.models import HoverTool
from bokeh.plotting import figure
from bokeh.transform import linear_cmap
from bokeh.palettes import Spectral4
from bokeh.models.graphs import from_networkx

# 创建一个NetworkX图
G = nx.karate_club_graph()

# 将图转换为邻接矩阵的形式
adj_matrix = nx.to_pandas_adjacency(G)

# 将邻接矩阵转换为DataFrame对象
df = pd.DataFrame(adj_matrix.values, columns=adj_matrix.columns, index=adj_matrix.index)

# 创建一个Bokeh的图形对象
plot = figure(title="NetworkX Graph with HoverTool")

# 将NetworkX图转换为Bokeh图形对象
graph_renderer = from_networkx(G, nx.spring_layout, scale=2, center=(0,0))

# 添加节点和边到图形对象
plot.renderers.append(graph_renderer)

# 获取节点标签信息
labels = df.columns.tolist()

# 创建悬停工具
hover = HoverTool(tooltips=[("Label", "@label")])

# 添加悬停工具到图形对象
plot.add_tools(hover)

# 显示图形
show(plot)