permute by rule

[AM]

(defun permute-by-rule (n rule row)
  (append (list row)
          (loop repeat n
            collect (setf row (position-filter rule row)))))

;; row => a row (or a list)
;; n => number of generations
;; rule => new position/order in every generation - keep attention it's 0-based!!! => for 12 pitches use 0 to 11

(permute-by-rule 20 '(2 0 1 5 11 3 8 6 4 9 10 7) (make-scale 'c4 12))

 

[AM]

an idea (permutationsfaktor) used by HELMUT LACHENMANN for many of his pieces - to organize/build his strukturnetz.

from an article by PIETRO CAVALLOTTI ("Die Funktion des Strukturnetzes am Beispiel von Mouvement (- vor der Erstarrung)")