Check for unused subsystem signals in InterconnectedSystem

[roryyorke]

Add capability to check for unused signals in InterconnectedSystem;
this check is invoked by default by interconnect.

This would have saved me a few hours when I made three typos in signal names, and I couldn't figure out why my time and frequency responses were all wrong.

Some questions:

• is check_unused=True a reasonable default? I think it is; it won't take long to scan the unused signals, and, if necessary, add them to the ignore_* lists
• are the ignore_* names reasonable? I initially called them dropped_inputs and dropped_outputs, but I decided against that. known_unused_inputs is more explicit, but a bit long.
• should this be in the InterconnectedSystem constructor, rather than in interconnect ?

[coveralls]

Coverage increased (+0.08%) to 90.006% when pulling faf3145 on roryyorke:rory/check-interconnect-signals into 5ab0a1c on python-control:master.

[murrayrm]

Quick responses on a few things, based on a quick read:

• I really like this functionality and completely agree we should include it!

• I think it would be OK to put this in the interconnect() function rather than the InterconnectedSystem constructor. The intent of interconnect() was to provide some additional processing and a more user-friendly interface.

• It looks like there are some glitches in the documentation (ignore_inputs appears twice).

[roryyorke]

Thanks for the feedback. I've fixed the docstring.

think it would be OK to put this in the interconnect()

OK, good. If InterconnectedSystem is used directly, check_unused_signals is available to be called after mappings have been set up. I also made unused_signals public, though I don't know what applications it could have.

While writing this, it occurred to me it wouldn't be all that hard to output a Graphviz dot file, or, possibly, a data structure that could be fed into NetworkX, to allow respectively visualization and graph-theoretic analysis of the signal flow, but I don't have time for any of that at the moment.

[sawyerbfuller]

Connecting @petercorke into this discussion because he is working on a nice-looking graphical renderer for this kind of interconnection. Not sure it is released yet though.

[petercorke]

It’s kind of released, just not publicised at the moment. If you pip install bdsim, then it is available as bdedit.py

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On 15 Sep 2021, at 6:10 am, sawyerbfuller ***@***.***> wrote: Connecting @petercorke <https://github.com/petercorke> into this discussion because he is working on a nice-looking graphical renderer for this kind of interconnection. Not sure it is released yet though. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#652 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AC2BIUTJMJFBZIRWI6N7TDDUB6T4FANCNFSM5D22EYMA>.