Markov-chain based generative Piano Music for SonicPi

markov-piano.rb

set :root, 60

T = 4.0

# This hash simulates a markov chain.
# Each key is the state and the array
# value represents the next state.
H = {
  60 => [58, 58, 58, 55, 60, 60, 60],
  58 => [60, 56, 56, 58, 60, 60],
  56 => [55, 58],
  55 => [60, 56, 60, 58, 58, 58, 58],
}

define :markov do |a, h|
  return h[a].sample # Chooses the next state at  random from hash
end

define :g do
  get[:root] # simplified root note getter
end

define :s do |n|
  set :root, n # simplified root note setter
end

define :r do
  (Math.cos(rand(180)) * 10).to_i # simplified random cosine index
end

s1 = scale(60, :aeolian) # working scale

p = [1,0,0,0,0,0,0,0].ring  # hi-hat pattern 1
p2 = [0,0,0,1].ring  # hi-hat pattern 2

live_loop :beat do
  sample :bd_fat, amp: 4
  sleep T / 8
end

live_loop :hats do
  sleep T / 16
  if p2.tick == 0
    sample :drum_cymbal_closed, amp: 1
  else
    sample :drum_cymbal_open, attack: 0.01, sustain: 0, release: 0.25
  end
  sleep T / 16
end

live_loop :right do
  sync :beat
  with_fx :reverb, mix: 0.5, room: 0.8 do
    use_synth :piano
    n1 = s1[r] # choose random note in scale
    n2 = s1[r - 5] # choose 4th of scale
    n3 = s1[r - 7] # choose 2nd of scale
    play n1, amp: 4, release: 5, sustain: 5
    (play n2, amp: 3, release: 5, sustain: 5) if p.tick == 1 # randomly form chords on leading edge of measure
    sleep (T / 8) + (T / 16)
    play n2, amp: 3, release: 5
    sleep (T / 16)
    play n3, amp: 3, release: 5
    sleep (T / 16)
    sleep (T / 8)
  end
end

live_loop :left do
  sync :beat
  with_fx :reverb, mix: 0.8, room: 0.8 do
    with_fx :echo, mix: 0.5 do
      use_synth :piano
      s markov(g, H) # update the state using markov chaining
      play (g - 12), release: 5, amp: 2, sustain: 5
      sleep T / 4 + T / 8
      play (g - 5), release: 3.5, amp: 2, sustain: 5
      sleep (T / 4) - (T / 8)
      sleep T / 4
    end
  end
end 

sb = (20..150).ring.mirror # simulate fade-up -> fade-down
  
live_loop :subass do
  with_fx :reverb, mix: 0.5 do
    with_fx :distortion, distort: (sb.tick * 0.01) do
      use_synth :sine
      play g, release: 15, amp: (sb.tick * 0.01) # play subbass sine
      sleep T / 1
    end
  end
end

There is an end missing in line 69 to finish the live_loop :right
Otherwise some nice interesting code!

@rbnpi good catch! fixed.

Just tried running the code but I get an error immediately on line 1, the post window says 'set' is an undefined method!

Any ideas?

joesh1: set and get were only added in version 3 of Sonic Pi. I expect you are trying it on an earlier version.

Ah yes, I should've noted that I'm running v3.1.0 @joesh1

very nice ,wonderful job