从散景中的 NetworkX 图形中获取选定的字形

Question

我正在尝试使用 Bokeh 中的 GraphRender 对象中的框 select 获取节点 selected 的索引，以便创建链接数据表。（我希望能够获得 selected 节点的索引）

这个问题有点类似于：但是我无法使用他们提出的解决方案来解决它。

完整的代码在下面，我试图用自定义 JS 回调来解决它，但我无法这样做。

非常感谢任何帮助。提前致谢！

（注意：这是我的第一个问题，如果需要更多信息，请告诉我。）

import pandas as pd
import numpy as np

from bokeh.layouts import row, widgetbox, column
from bokeh.models import ColumnDataSource, CustomJS, StaticLayoutProvider, Oval, Circle
from bokeh.models import HoverTool, TapTool, BoxSelectTool, GraphRenderer
from bokeh.models.widgets import RangeSlider, Button, DataTable, TableColumn, NumberFormatter
from bokeh.io import curdoc, show, output_notebook
from bokeh.plotting import figure

import networkx as nx

from bokeh.io import show, output_file
from bokeh.plotting import figure
from bokeh.models.graphs import from_networkx, NodesAndLinkedEdges, EdgesAndLinkedNodes, NodesOnly

# Import / instantiate networkx graph
G = nx.Graph()

G.add_edge('a', 'b', weight=0.6)
G.add_edge('a', 'c', weight=0.2)
G.add_edge('c', 'd', weight=0.1)
G.add_edge('c', 'e', weight=0.7)
G.add_edge('c', 'f', weight=0.9)
G.add_edge('a', 'd', weight=0.3)

# Node Characteristics
node_name = list(G.nodes())
positions = nx.spring_layout(G)

node_size = [k*4 for k in range(len(G.nodes()))]
nx.set_node_attributes(G, node_size, 'node_size')
visual_attributes=ColumnDataSource(
    pd.DataFrame.from_dict({k:v for k,v in G.nodes(data=True)},orient='index'))

# Edge characteristics
start_edge = [start_edge for (start_edge, end_edge) in G.edges()]
end_edge = [end_edge for (start_edge, end_edge) in G.edges()]
weight = list(nx.get_edge_attributes(G,'weight').values())

edge_df = pd.DataFrame({'source':start_edge, 'target':end_edge, 'weight':weight})

# Create full graph from edgelist 
G = nx.from_pandas_edgelist(edge_df,edge_attr=True)

# Convert full graph to Bokeh network for node coordinates and instantiate Bokeh graph object 
G_source = from_networkx(G, nx.spring_layout, scale=2, center=(0,0))
graph = GraphRenderer()

# Update loop where the magic happens
def update():
    selected_df = edge_df[(edge_df['weight'] >= slider.value[0]) & (edge_df['weight'] <= slider.value[1])]
    sub_G = nx.from_pandas_edgelist(selected_df,edge_attr=True)
    sub_graph = from_networkx(sub_G, nx.spring_layout, scale=2, center=(0,0))
    graph.edge_renderer.data_source.data = sub_graph.edge_renderer.data_source.data
    graph.node_renderer.data_source.data = G_source.node_renderer.data_source.data
    graph.node_renderer.data_source.add(node_size,'node_size')

def selected_points(attr,old,new):
    selected_idx = graph.node_renderer.selected.indices #does not work
    print(selected_idx)

# Slider which changes values to update the graph
slider = RangeSlider(title="Weights", start=0, end=1, value=(0.25, 0.75), step=0.10)
slider.on_change('value', lambda attr, old, new: update())

# Plot object which is updated 
plot = figure(title="Meetup Network Analysis", x_range=(-1.1,1.1), y_range=(-1.1,1.1),
             tools = "pan,wheel_zoom,box_select,reset,box_zoom,crosshair", plot_width=800, plot_height=800)

# Assign layout for nodes, render graph, and add hover tool
graph.layout_provider = StaticLayoutProvider(graph_layout=positions)
graph.node_renderer.glyph = Circle(size='node_size')
graph.selection_policy = NodesOnly()
plot.renderers.append(graph)
plot.tools.append(HoverTool(tooltips=[('Name', '@index')]))

# Set layout
layout = column(slider,plot)

# does not work
#graph.node_renderer.data_source.on_change("selected", selected_points)

# Create Bokeh server object
curdoc().add_root(layout)
update()

Answer 1

不要将监听器放在 graph.node_renderer.data_source.on_change 上，而是使用它：

graph.node_renderer.data_source.selected.on_change("indices", selected_points)

这会触发服务器端响应。

弘毅

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