Plex and plexamp already have a number of options for automatically creating playlists: Radios or sound journeys created based on certain criteria.
The Meloday script, which can be found here, takes a time of day or mood-based approach. Meloday creates playlists for the respective time of day, be it morning, afternoon or late at night. It does this by using tracks that have already been played at those times, and adding tracks with sonic similarities to this framework.
It even uses artificial intelligence, but not to generate the playlist itself, just to reformulate the names and descriptions of the new playlists.
There are many enthusiastic voices on reddit\/plexamp, even Elan Feingold, one of the founders of Plex, has commented positively - so it's worth giving it a try.
