Slider based on Networkx node attribute value with Bokeh - bokeh

Question

I am attempting to develop a slider which will limit the number of nodes visible in a network graph based on the value of a node's attribute. The below Pandas DataFrame (df) represents the nodes, and the node's associated attributes (count information).
source target source_count target_count
A C 15 10
A D 15 20
A E 15 30
B F 25 10
B G 25 20
B H 25 30
I have used the following code to generate a network graph for the nodes and their associated attributes.
import pandas as pd
from bokeh.layouts import column, widgetbox,layout,
from bokeh.plotting import figure, show, output_file,
from bokeh.models import HoverTool, value,PanTool, LabelSet, Legend, ColumnDataSource,Circle,Plot, Range1d, MultiLineBoxSelectTool,ResetTool,LassoSelectTool,Slider
from bokeh.models.callbacks import CustomJS
from bokeh.models.graphs import from_networkx, NodesAndLinkedEdges, EdgesAndLinkedNodes
df = pd.DataFrame({
"source":["A", "A", "A", "B", "B","B"],
"target":["C", "D", "E", "F", "G","H"],
"source_count":["15", "15", "15", "25","25","25"]
"target_count":["10", "20", "30", "10","20","30"]
})
net_graph = from_pandas_edgelist(df, 'source', 'target')
#assign attributes
for index, row in df.iterrows():
net_graph.nodes[row['source']]['yearly_count'] = row['source_count']
net_graph.nodes[row['target']]['yearly_count'] = row['target_count']
graph_plot= Plot(plot_width=800, plot_height=600,
x_range=Range1d(-1.1, 1.1), y_range=Range1d(-1.1, 1.1))
node_hover_tool = HoverTool(tooltips=[("Name", "#index"),("Yearly Count", "#yearly_count")])
graph_plot.add_tools(node_hover_tool)
graph_setup = from_networkx(net_graph, nx.spring_layout, scale=1, center=(0, 0))
graph_setup.node_renderer.glyph = Circle(size=20,fill_color = 'blue')
graph_setup.edge_renderer.glyph = MultiLine(line_color="red", line_alpha=0.8, line_width=1)
graph_plot.renderers.append(graph_setup)
output_file("test_1.html")
show(graph_plot)
The slider I am trying to would use the yearly_count attribute to limit the number of nodes on display. I know that Bokeh allows the embedding of a JavaScript Callback, however, I have not seen a use-case integrated with NetworkX.
Any assistance that anyone could provide would be greatly appreciated.

Answer 1

If you can run your app with bokeh serve then I would try:
from bokeh.models import Slider
graph_plot= Plot()
graph_setup.node_renderer.glyph = Circle()
graph_setup.edge_renderer.glyph = MultiLine()
def callback(attr, old, new):
//filter your data here to show less nodes and edges based
graph_setup.node_renderer.data_source.data = data
graph_setup.edge_renderer.data_source.data = data
slider = Slider()
slider.on_change('value', callback)
If you want to run a Bokeh standalone app then replace slider callback with:
code = """
//filter your data here to show less nodes and edges
graph_setup.node_renderer.data_source.data = data;
graph_setup.edge_renderer.data_source.data = data; """
callback = CustomJS(args = dict(graph_setup = graph_setup, data = data), code = code)
slider = Slider()
slider.js_on_change('value', callback)
See complete JS callback example below:
import networkx as nx
from bokeh.io import show, output_file
from bokeh.models import Plot, Range1d, MultiLine, Circle, TapTool, OpenURL, HoverTool, CustomJS, Slider, Column
from bokeh.models.graphs import from_networkx, EdgesAndLinkedNodes
from bokeh.palettes import Spectral4
from dask.dataframe.core import DataFrame
import pandas as pd
data = {'source': ['A', 'A', 'A', 'A', 'A', 'A'], 'target': ['C', 'D', 'E', 'F', 'G', 'H'], 'source_count': [15, 15, 15, 25, 25, 25], 'target_count': [10, 20, 30, 10, 20, 30]}
df = pd.DataFrame(data)
net_graph = nx.from_pandas_edgelist(df, 'source', 'target')
for index, row in df.iterrows():
net_graph.nodes[row['source']]['yearly_count'] = row['source_count']
net_graph.nodes[row['target']]['yearly_count'] = row['target_count']
graph_plot = Plot(plot_width = 800, plot_height = 600, x_range = Range1d(-1.1, 1.1), y_range = Range1d(-1.1, 1.1))
node_hover_tool = HoverTool(tooltips = [("Name", "#index"), ("Yearly Count", "#yearly_count")])
graph_plot.add_tools(node_hover_tool)
graph_setup = from_networkx(net_graph, nx.spring_layout, scale = 1, center = (0, 0))
graph_setup.node_renderer.glyph = Circle(size = 20, fill_color = 'blue')
graph_setup.edge_renderer.glyph = MultiLine(line_color = "red", line_alpha = 0.8, line_width = 1)
graph_plot.renderers.append(graph_setup)
code = """
var new_start = start.slice();
var new_end = end.slice();
new_index = end.slice();
new_start = new_start.splice(0, cb_obj.value)
new_end = new_end.splice(0, cb_obj.value)
new_index = ['A'].concat(new_end)
new_data_edge = {'start': new_start, 'end': new_end};
new_data_nodes = {'index': new_index};
graph_setup.edge_renderer.data_source.data = new_data_edge;
graph_setup.node_renderer.data_source.data = new_data_nodes;
"""
callback = CustomJS(args = dict(graph_setup = graph_setup,
start = df['source'].values,
end = df['target'].values), code = code)
slider = Slider(title = 'Slider', start = 1, end = 6, value = 6)
slider.js_on_change('value', callback)
layout = Column(graph_plot, slider)
show(layout)
Result:

Answer 2

Newer versions of Bokeh uses strict mode for JavaScript (see release log), which implies that code from Tony's accepted answer does not work for Bokeh version 2.0.0 and upwards. Only a few small explicit declarations of variables are needed for the code to work for newer Bokeh versions:
code = '''
var new_start = start.slice();
var new_end = end.slice();
var new_index = end.slice();
new_start = new_start.splice(0, cb_obj.value)
new_end = new_end.splice(0, cb_obj.value)
new_index = ['A'].concat(new_end)
var new_data_edge = {'start': new_start, 'end': new_end};
var new_data_nodes = {'index': new_index};
graph_setup.edge_renderer.data_source.data = new_data_edge;
graph_setup.node_renderer.data_source.data = new_data_nodes;
'''