如何将Holoviews图转换为Bokeh'模型'，以利用更多Bokeh功能，例如bokeh.models.GraphRenderer和node_renderer？

Question

我正在尝试使用networkx和bokeh创建有向图，但是，我还想显示每个边缘的箭头。 我发现Holoviews库具有向其图构造函数添加“ directed = true”参数的功能。 但是，我也想利用Bokeh的设计功能，例如根据先前设置的节点属性调整节点颜色/大小。 仅当我使用Bokeh的from_networkx（）获取bokeh.models.renderers.GraphRender对象，然后使用其属性node_renderer和edge_renderer时，后者才有效。

问题是使用Holoviews渲染器将Bokeh指定为后端时，它返回bokeh.plotting.figure.Figure而不是GraphRenderer。 最终，我想知道如何能够通过散景可能的某些属性来控制节点的大小/颜色，并同时使用Holoviews在每个边缘上显示箭头。

import networkx as nx
import holoviews as hv
from holoviews import opts
hv.extension('bokeh')
from bokeh.io import show, output_file

# ... some code for I/O ...
G = nx.DiGraph(edgeList)   # Directed networkx graph

# Set Node/Edge attributes to display upon hover
numConnections = {k:v for k,v in G.out_degree()}
nx.set_node_attributes(G, numConnections, name='numConnections')

# Returns Holoviews graph
hvGraph = hv.Graph.from_networkx(G, nx.spring_layout).opts(tools=['hover'], directed=True, arrowhead_length=0.01)
# Renders Holoviews graph into bokeh.plotting.figure.Figure
hvRendered = hv.render(hvGraph, 'bokeh')

output_file("out.html")
show(hvRendered)


# # The below code runs as expected using Bokeh only, and not Holoviews 
# # to produce the directed graph (without arrowed edges):

# from bokeh.models import Plot, Range1d, MultiLine, Circle
# from bokeh.models import LinearColorMapper, ColorBar, BasicTicker
# import bokeh.models as bm
# from bokeh.models.graphs import from_networkx
# from bokeh.models.graphs import NodesAndLinkedEdges, EdgesAndLinkedNodes


# # Returns GraphRenderer from bokeh.models.renderers.DateRenderer 
# graphRenderer = from_networkx(G, nx.spring_layout)

# mapper = LinearColorMapper(palette="Viridis256", low=76, high=0)

# # Node size/color when unselected / selected / hover
# graphRenderer.node_renderer.glyph = Circle(
#     size='node_size',
#     fill_color= {'field': "numConnections", "transform": mapper},
#     fill_alpha=.8
# )
# graphRenderer.node_renderer.selection_glyph = Circle(
#     size=25,
#     fill_color=Inferno6[4]
# )
# graphRenderer.node_renderer.hover_glyph = Circle(
#     size=20,
#     fill_color=Inferno6[3]
# )

# # Edge size/color when unselected / selected / hover
# graphRenderer.edge_renderer.glyph = MultiLine(
#     line_color="#CCCCCC",
#     line_alpha=0.8,
#     line_width=3
# )
# graphRenderer.edge_renderer.selection_glyph = MultiLine(
#     line_color=Inferno6[4],
#     line_width=4
# )
# graphRenderer.edge_renderer.hover_glyph = MultiLine(
#     line_color=Inferno6[3],
#     line_width=4
# )

# graphRenderer.node_renderer.data_source.data['numConnections'] = [v for k,v in 
    nx.get_node_attributes(G,'numConnections').items()]

# graphRenderer.selection_policy = NodesAndLinkedEdges()
# graphRenderer.inspection_policy = NodesAndLinkedEdges()

# bar = ColorBar(color_mapper=mapper, location=(0,0),     title='#connections')

# # Create Bokeh Plot
# plot = Plot(
#     plot_width=20,
#     plot_height=20,
#     x_range=Range1d(-1.1,1.1),
#     y_range=Range1d(-1.1,1.1)
# )

# plot.add_tools(
#     bm.HoverTool(tooltips=[("#connections", "@numConnections")]),
#     bm.TapTool(),
#     bm.BoxSelectTool()
# )
# plot.renderers.append(graphRenderer)

# output_file("bokeh.html")
# show(plot)

将Holoview图渲染到Bokeh Figure（而不是models.GraphRenderer）之后，如果我尝试使用渲染的Bokeh Figure对象调用属性node_renderer，则显然会引发异常。

追溯（最近一次呼叫最近）：hvRenderedGraph.node_renderer.selection_glyph = Circle（）中的文件“ holoview.py”，第106行，AttributeError：“ BokehRenderer”对象没有属性“ node_renderer”

Answer 1

您可以通过以下代码获取GraphRender对象：

from bokeh.models import GraphRenderer
gr = hvRendered.select_one(GraphRenderer)

然后使用gr.node_renderer和gr.edge_renderer调整样式。