Avoid KeyError when overlaying dynamic groupbys

[jlstevens]

WIP

Here is the test example:

import holoviews as hv
import pandas as pd
import numpy as np
hv.extension('bokeh')

df1 = pd.DataFrame({'sym':['CAT1']*5 + ['CAT2']*5, 'x':list(range(10)), 'y':np.random.rand(10)})
df2 = pd.DataFrame({'sym':['CAT1']*10, 'x':list(range(10)), 'y':np.random.rand(10)})

ds1 = hv.Dataset(df1)
ds2 = hv.Dataset(df2)
ds1.to(hv.Spikes, 'x', 'y', groupby=['sym'], dynamic=True) * ds2.to(hv.Spikes, 'x', 'y', groupby=['sym'], dynamic=True).opts(color='blue')

With this PR you can select CAT2:

On main you get a keyerror:

Traceback (most recent call last): File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/renderer.py", line 538, in plotting_class plotclass = Store.registry[cls.backend][element_type] KeyError: None

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/pyviz_comms/init.py", line 338, in _handle_msg
self._on_msg(msg)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/viewable.py", line 294, in _on_msg
doc.unhold()
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/bokeh/document/document.py", line 799, in unhold
self.callbacks.unhold()
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/bokeh/document/callbacks.py", line 396, in unhold
self.trigger_on_change(event)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/bokeh/document/callbacks.py", line 373, in trigger_on_change
invoke_with_curdoc(doc, event.callback_invoker)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/bokeh/document/callbacks.py", line 408, in invoke_with_curdoc
return f()
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/bokeh/util/callback_manager.py", line 191, in invoke
callback(attr, old, new)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/reactive.py", line 405, in _comm_change
state._handle_exception(e)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/io/state.py", line 391, in _handle_exception
raise exception
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/reactive.py", line 403, in _comm_change
self._schedule_change(doc, comm)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/reactive.py", line 385, in _schedule_change
self._change_event(doc)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/reactive.py", line 381, in _change_event
self._process_events(events)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/reactive.py", line 319, in process_events
self.param.update(**self_events)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/param/parameterized.py", line 1898, in update
self._batch_call_watchers()
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/param/parameterized.py", line 2059, in batch_call_watchers
self._execute_watcher(watcher, events)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/param/parameterized.py", line 2021, in _execute_watcher
watcher.fn(*args, **kwargs)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/pane/holoviews.py", line 240, in _widget_callback
self._update_plot(plot, pane)
File "/Users/jstevens/miniconda3/envs/analytics/lib/python3.7/site-packages/panel/pane/holoviews.py", line 222, in _update_plot
plot.update(key)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/plot.py", line 937, in update
item = self.getitem(key)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/plot.py", line 423, in getitem
self.update_frame(frame)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/bokeh/element.py", line 2432, in update_frame
defaults=False)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/plot.py", line 890, in _traverse_options
traversed = obj.traverse(lookup, specs)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/core/dimension.py", line 662, in traverse
accumulator += el.traverse(fn, specs, full_breadth)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/core/dimension.py", line 655, in traverse
accumulator.append(fn(self))
File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/plot.py", line 879, in lookup
options = cls.lookup_options(x, opt_type)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/plot.py", line 275, in lookup_options
return lookup_options(obj, group, cls.backend)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/core/options.py", line 94, in lookup_options
plot_class = Store.renderers[backend].plotting_class(obj)
File "/Users/jstevens/Desktop/development/holoviews/holoviews/plotting/renderer.py", line 540, in plotting_class
raise SkipRendering(f"No plotting class for {element_type.name} found")
AttributeError: 'NoneType' object has no attribute 'name'

I thought I could return an empty element from the dynamicmap created by groupby in the .to call but I always hit key errors in the plotting code until this change.

[codecov-commenter]

Codecov Report

Merging #5603 (0a14467) into main (387503f) will decrease coverage by 0.01%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##             main    #5603      +/-   ##
==========================================
- Coverage   88.33%   88.33%   -0.01%     
==========================================
  Files         302      302              
  Lines       62428    62430       +2     
==========================================
+ Hits        55147    55148       +1     
- Misses       7281     7282       +1     

Impacted Files	Coverage Δ
holoviews/plotting/plot.py	93.44% <50.00%> (-0.08%)	⬇️

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[jlstevens]

Closing in favor of #5604 - turns out it was just a bug in formatting an error message!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.