shuffle

Function

(shuffle list {keyword value}*)

Returns a random ordering of list according to the keyword arguments specified to the function.

shuffle supports the following keyword arguments:

:copy boolean: If true then list is copied before it is shuffled otherwise list is destructively modified. The default value is true.
:start integer: An optional lower bound on element reordering.
:end integer: An optional exclusive upper bound on element reordering.
:state random-state: The random state to use. The default value is *random-state*.

Examples

;; The shuffle function.
(shuffle '(a b c d e))
⇒ (b a e d c)
(shuffle '(a b c d e))
⇒ (c e b a d)
(shuffle '(a b c d e) :start 2)
⇒ (a b e d c)
(shuffle '(a b c d e) :start 2)
⇒ (a b d e c)
;; Shuffling notes.
(define (play-shuffle reps notes rate )
  (let ((len (length notes)))
    (process for i below reps
             for j = (mod i len)
             when (= j 0) ; need to reshuffle?
             do (shuffle notes :copy #f)
             output (new midi :time (now)
                         :keynum (list-ref notes j)
                         :duration (* rate 1.5)
                         :amplitude (interp j 0 .4 (- len 1) .8))
             wait rate)))

(events (play-shuffle 60 (note '(c d ef f g a bf c5)) .1)
        "test.mid")
⇒ "test.mid"

shuffle

Examples

See also