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Jamnetic Algorhythms

Using genetica algorithms to improvise over midi



Must use python 3.6

  • Run pip install -r requirements.txt (or pip3 if you don't have a virtualenv set up)
  • Run python or python3
  • The pieces will be written out to /pieces
    • To change the piece being generated, modify the piece_num variable to represent the index you want

To add your own pieces, observe and replace the mxl file with your musicxml file, and the chord progression with a corresponding chord progression. Then, import your new python file into

Algorithm Thoughts

  • GAs for jazz standard - all of me
    • melody only tho, but maintain info about chord progressions
  • Mutation = take random note in a measure, maybe for 4 random measures
    • (should we weight based on note length or nah)
    • (or maybe weight based on 'strength' of note position, i.e. notes that fall on beat 1 weighted higher than beats on & of 2)
      1. 0.25 probability of picking a random chord tone / note in the key?
      • maybe consider whether or not it's on strong beat
      • add any domain knowledge, or nah?
    • 2a. 0.125 probability of copying a random note already in the measure
    • 2b. 0.125 probability of transposing up/down a whole note
      • 0.5 up, 0.5 down
    • 3a. 0.25 (1 - quanta/4) probability of becoming leading note, chromatic up or down depending on beat?
      • quanta = 1 for quarter note, .5 for eighth, etc.
    • 3b. 0.25 * (quanta/4) probability of becoming split
      • 0.5 prob of even split
      • 0.25 of triplet
      • 0.25 of dotted and
        • 0.5 of short beat first
        • 0.5 of long beat first
      • apply rules 1,2,4, 7 to new notes
      • apply some min/max, where quanta turns to 0 if it's sixteenth note, also no triplet splitting
      1. 0.05 probability of picking note from bar with same chord progression
      • if no such bars exist, we reweight and ignore this possibility
      1. 0.05 probability of shifting all notes
      • 0.5 of going to right, 0.5 of going to left
      1. 0.05 probability of shuffling notes
      • 0.5 of just shuffling notes themselves
      • 0.5 of shuffling notes + rhythmic structure
      1. 0.05 probability of dropping note
      1. 0.05 probability of swapping notes
  • Crossover ideas
    • split/join
      • Take half of bar and combine to half of other bar
      • probably better to add whole measures
      • alternate every measure?
      • take first half from one and second from other?
  • reduce
    • pick pieces w/ highest fitness, leave in some wonky ones, bc "that's jazz"
  • fitness function
    • dock points for no note variation
    • dock points for all notes identical to original
    • dock points for having 0 notes from chord progression
    • dock points for only having notes from chord progression
    • dock points for too many jumps
    • dock points if first note is an ugly interval off chord root (half step, 6 half steps, ignoring notes where it should belong like a maj7 / m7b5) Other thoughts
  • add inversions to chords
  • consider weighting everything based on quanta & 1-quanta
  • have a corpus of jazz standards to borrow phrases from
  • add different improvs of all of me to the initial population
  • dock points if duration is wonky number
  • plus points for repitition of musical phrases / rhythmic combinations?


🐛 🎼 Using genetic algorithms to improvise over jazz standards



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