hysteresis-function

[AM]

here is a little function, to use or optimize...

greetings

andré

 

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; a little lisp-function that's switches by a "hysteresis" from one value to the other ;;;;;;;;;;;;;;;;;;;;;;;
;;;; could be used for any-value
;;;; :start-weight -> tendency at the beginning 
;;;; :sensitivity -> change-step of tendency when switch/match
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;;; subfunctions

(defun weighted-random (list)
  (loop for item in list
            with rand-num = (random (loop for x in list sum (second x)))
            for add = (second item) then (+ add (second item))
            when (< rand-num add) return (first item)))

(defun weighted-t/nil (on-weight)
  (let ((off-weight (- 1 on-weight)))
    (weighted-random (list (list 't on-weight) (list 'nil off-weight)))))

(weighted-t/nil 0.5)

;;;; mainfunction

(defun binary-hysteresis-1.0 (&key number-of-values (values '(0 1)) (start-weight 0.1) (sensitivity 0.02))
  (loop repeat number-of-values
    with weight = start-weight
    with cnt = 0
    when (equal (weighted-t/nil weight) 'nil)
    collect (first values)  else collect (second values) and do (incf cnt)
    when (= cnt 3) do (setq weight (+ weight sensitivity)
                            cnt 0)))

;;;; example with 0/1
(length-list-plot (binary-hysteresis-1.0 :number-of-values 200
                                         :values '(0 1)
                                         :start-weight 0.1
                                         :sensitivity 0.07))


;;;; example with two pitches
(make-omn :pitch (binary-hysteresis-1.0 :number-of-values 200
                                        :values '(c4 c5)
                                        :start-weight 0.05
                                        :sensitivity 0.1)
          :length (gen-repeat 200 '(1/32)))

 

[Stephane Boussuge]

hI André,

 

thanks for this but it seem we need the function weighted-random:

"In weighted-t/nil: Undefined function weighted-random"

 

S.

[AM]

you are wright! :-) violà!! have a look to the edited post!

there was also a "BUG" in the code, now it's seems okay!!

[AM]

 

BINARY-HYSTERESIS-1.1

 

version with :start-point (default is ( /  numbers-of-values 2))

it's interesting to play with :tendency and :start-weight

for example -> start-weight = high (ca. 0.5) -> oscillation is beginning quickly (at start-point) but when tendency is low it needs time to switch definitly... etc...

 

(defun binary-hysteresis-1.1 (&key number-of-values (values '(0 1)) (start-weight 0.1) (sensitivity 0.02) (start-point (if (evenp number-of-values)
                                                                                                                           (/ number-of-values 2)
                                                                                                                           (/ (1- number-of-values) 2))))
  (loop repeat number-of-values
    with weight = start-weight
    with cnt1 = 0
    for cnt2 = 0 then (incf cnt2)
    when (or (equal (weighted-t/nil weight) 'nil)
             (< cnt2 start-point))
    collect (first values) else collect (second values) and do (incf cnt1) 
    when (= cnt1 3) do (setq weight (+ weight sensitivity)
                            cnt1 0)))


;;;; example with 0/1
(length-list-plot (binary-hysteresis-1.1 :number-of-values 200
                                         :values '(0 1)
                                         :start-weight 0.4
                                         :sensitivity 0.05
                                         :start-point 80))

 

[Stephane Boussuge]

Thanks you for this interesting hysterical functions ;-)

 

SB.

 

[AM]

"hysterical" with a value-list = multiple states :-)

 

;;;; SUBFUNCTIONS

(defun weighted-random (list)
  (loop for item in list
            with rand-num = (random (loop for x in list sum (second x)))
            for add = (second item) then (+ add (second item))
            when (< rand-num add) return (first item)))

(defun weighted-t/nil (on-weight)
  (let ((off-weight (- 1 on-weight)))
    (weighted-random (list (list 't on-weight) (list 'nil off-weight)))))

(weighted-t/nil 0.5)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;;; MAINFUNCTION
                            
(defun binary-hysteresis-1.2 (&key number-of-values (value-list '((0 1) (4 0) (0 1) (4 7))) (start-weight 0.1) (sensitivity 0.02) (static 1.0))
  (loop repeat number-of-values
    with weight = start-weight
    with cnt1 = 0
    with cnt-v = 0
    when (equal (weighted-t/nil weight) 'nil)
    collect (first (nth cnt-v value-list)) else collect (second (nth cnt-v value-list)) and do (incf cnt1) 
    when (= cnt1 3) do (setq weight (+ weight sensitivity)
                             cnt1 0)

    when (> weight static)
    do (incf cnt-v)
    and do (setq weight start-weight)
    when (= cnt-v (length value-list)) do (setq cnt-v 0)))

;;example
(length-list-plot (binary-hysteresis-1.2 :number-of-values 600
                                         :start-weight 0.1
                                         :sensitivity 0.05
                                         :value-list '((0 1) (10 2) (7 3))
                                         :static 2.0))