[BUG] internal reporting for node.isolated may be incorrect

[tommypurves]

Describe the bug
Calling len(list(networkx.isolates(G)) and sum(get_all_isolation()) return different values. This is because when a node is isolated by the blue agent, there is no check for previously connected nodes, and if any nodes that are not the target node have been made isolated.

An extreme example is that isolating the centre node in a star network of N nodes, on the one hand should report all nodes as isolated (as the len(list(networkx.isolates(G)) does), however only one node is reported as isolated internally (the sum of the return for get_all_isolation() method)

To Reproduce
Steps to reproduce the behaviour:
2. Instantiate env = GenericNetworkEnv
3. Print env.network_interface.get_all_isolation() and len(list(networkx.isolates(env.network_interface.current_graph)))
5. See error

Expected behaviour
We would expect that isolating a node, might have the effect of isolating other nodes that are not the target node. However, this is not recorded internally, which might effect proper rewards calculation (e.g. for rewards that are proportional to the number of isolated nodes, or the change in the number of isolated nodes).

Screenshots/Outputs

The below code should additionally check and set isolated nodes that are not the target node

Environment (please complete the following information):
Checked with:

• [Python 3.9.13]
• YT Version: [e.g. v1.0.1]
  It might also be a problem in the latest, after scanning the code.

[ChrisMcCarthyDev]

Thank you for raising this. This has been added to our internal backlog (reference 1644) and will be looked into by one of the dev team soon.