How can I create a random set of lengths that follows a defined trend,

for example:

Create a rhythm over 4 bars that starts with only q and e. then accelerating up to bar 3 where it reaches lengths down to t and then decellerating back again until the end of bar 4.

 

;; Some suggestion of possible path to explore to create rhythmic progressions
;; Example1
(setf vector (list-plot (half-sine 24 1) :join-points t))
(setf len1 (vector-to-length '1/32 8 1 vector))

;; Example 2
(setf size 4)
(setf len2 (gen-length-density size :density '(10 50 100 20) :level 16))
;;or
(setf len3 (gen-length-density size :density '(10 50 100 20) :level 16 :type 2))


;; Example 3
(setf vector2 (list-plot (half-sine 24 1) :join-points t))
(setf divlist (vector-round 1 8 vector2))
(setf len4 (gen-tuplet 1 1 'd 'n 'q divlist))
(setf len5 (gen-tuplet 1 1 'd '? 'q divlist))

;; Example 4
(setf len6 (rhythm-series 1 '(4 8 12 16 32 16 8 4) 4/4))

Etc, etc...

There is infinite possibilities in Opusmodus, your imagination is the limit.