transition with fibonacci

;;little function to make a transition by FIBONACCI-seq
;;i have seen this idea in "slippery chicken" (by michael edwards),
;;so here is a - "not so smart" but working - basic-function.

(defun transition-with-fibonacci (number-of-values value-a value-b) 
  (let ((fib-length) (fib-seq) (all-seq))
    (setq fib-length (loop
                       for cnt = 1 then (incf cnt)
                       collect (sum (fibonacci 2 cnt)) into bag
                       when (> (car (last bag)) number-of-values)
                       do (return (1- (length bag)))) 
          fib-seq (fibonacci 2 fib-length)
          all-seq (append (reverse fib-seq) (loop repeat (- number-of-values (sum fib-seq))
                                              collect 1)))
    (loop for i in all-seq 
      append (loop repeat i
               for cnt = 0 then (incf cnt)
               when (= cnt 0)
               collect value-b else collect value-a))))



;;example-1 => only the process
(transition-with-fibonacci 70 1 2)

;;example-2 => with context = sequence with 1 or 2 (before/after transition)
(list-plot
 (append  (gen-repeat 10 1) 
          (transition-with-fibonacci 32 1 2)
          (gen-repeat 10 2))
 :zero-based t
 :point-radius 2
 :join-points t)