(see also)
retrometro1.mid (retrometro1.py -- warning: ugly (this is what my code looks like while its still evolving))
... <brainwave/> I've been thinking of each note as a single Metropolis sampler step, and adding a cludgy thing to make it consider multiple note destinations per step. I now think I may be better off considering notes as regularly subsampled from a completely normal Metropolis sampler. Here's the neat bit: Previously it never repeated the same note (midi above has a cludge to add repeats, but it's a bit too uniform). Note hits only occurred when the note changed. But with the subsampling method, I can say "repeat the note whenever there is a change, even if it changes back before the next note". This is neat because "unstable" notes, notes with close neighbours of comparable likelihood, get lots of repeats.
Midi will be forthcoming eventually...