Opacity behavior when removing vertex

[fsoupimenta]

Hello, I'm working on a project that uses Netgraph, and when i remove a vertex that has one of its adjacent ones with opacity 1, the opacity of the other vertices bugs and they behave strangely.

• It's hard to explain, so I made a gif to demonstrate the situation:

• In my console, i got the following traceback:

  Traceback (most recent call last):
  File "C:\Users\Fernando Pimenta\Documents\Github\GraphFilter\venv\lib\site-packages\matplotlib\cbook\__init__.py", line 307, in process
  func(*args, **kwargs)
  File "C:\Users\Fernando Pimenta\Documents\Github\GraphFilter\venv\lib\site-packages\netgraph\_interactive_variants.py", line 203, in _on_motion
  super()._on_motion(event)
  File "C:\Users\Fernando Pimenta\Documents\Github\GraphFilter\venv\lib\site-packages\netgraph\_main.py", line 2621, in _on_motion
  EmphasizeOnHoverGraph._on_motion(self, event)
  File "C:\Users\Fernando Pimenta\Documents\Github\GraphFilter\venv\lib\site-packages\netgraph\_main.py", line 2071, in _on_motion
  artist.set_alpha(self._base_alpha[artist])
  KeyError: <netgraph._artists.EdgeArtist object at 0x000001670E5BC700>

[paulbrodersen]

Sorry, I had not considered this edge case. Steps to reproduce:

1) Select a node with multiple outgoing edges. 2) Hover over an incident edge such that it is emphasized and all other edges are de-emphasized. 3) Delete node while hovering over the edge.

Removing the node also removes the incident edges, but the de-emphasized edges are still in the list of de-emphasized artists. The attempt to reverse the opacity results in the error.

[paulbrodersen]

The latest commit mitigates the issue such that it should no longer result in an error, and the appearances of all artists should be restored to normal on the first movement.

Note to future self: for some reason, the artists for the de-emphasized edges aren't removed from self.deemphasized_artists when deleting the edge, although we explicitly do so in _interactive_variants.MutableGraph._delete_edge.