[CM] Rearranging a sequence

[Rick Taube]

you shouldnt "rearrange the time values" of the seq's objects -- the  
purpose of a seq is maintain a time-ordered list of events!

assuming you want to scramble keynumbers or something like that you  
could do this

;; create a seq of midis

(defparameter myseq
   (new seq :subobjects (loop for i to 100
			  collect (new midi :time i :keynum i))))

;; look at the first ten

(list-objects myseq :end 10)

0. #i(midi time 0 keynum 0 duration 0.5 amplitude 64 channel 0)
1. #i(midi time 1 keynum 1 duration 0.5 amplitude 64 channel 0)
2. #i(midi time 2 keynum 2 duration 0.5 amplitude 64 channel 0)
3. #i(midi time 3 keynum 3 duration 0.5 amplitude 64 channel 0)
4. #i(midi time 4 keynum 4 duration 0.5 amplitude 64 channel 0)
5. #i(midi time 5 keynum 5 duration 0.5 amplitude 64 channel 0)
6. #i(midi time 6 keynum 6 duration 0.5 amplitude 64 channel 0)
7. #i(midi time 7 keynum 7 duration 0.5 amplitude 64 channel 0)
8. #i(midi time 8 keynum 8 duration 0.5 amplitude 64 channel 0)
9. #i(midi time 9 keynum 9 duration 0.5 amplitude 64 channel 0)

;; gather the keynumbers

(defparameter seqkeys
   (fold-objects #'cons myseq '() :slot 'keynum))

;; now shuffle the keynums and put them back

(let ((mixedup (shuffle seqkeys)))
   (loop for m in (subobjects myseq)
      for k in mixedup
      do (sv m :keynum k))
   )

;; look at them again

(list-objects myseq :end 10)

0. #i(midi time 0 keynum 60 duration 0.5 amplitude 64 channel 0)
1. #i(midi time 1 keynum 68 duration 0.5 amplitude 64 channel 0)
2. #i(midi time 2 keynum 15 duration 0.5 amplitude 64 channel 0)
3. #i(midi time 3 keynum 51 duration 0.5 amplitude 64 channel 0)
4. #i(midi time 4 keynum 29 duration 0.5 amplitude 64 channel 0)
5. #i(midi time 5 keynum 52 duration 0.5 amplitude 64 channel 0)
6. #i(midi time 6 keynum 35 duration 0.5 amplitude 64 channel 0)
7. #i(midi time 7 keynum 74 duration 0.5 amplitude 64 channel 0)
8. #i(midi time 8 keynum 25 duration 0.5 amplitude 64 channel 0)
9. #i(midi time 9 keynum 16 duration 0.5 amplitude 64 channel 0)
CM>






On Apr 9, 2007, at 6:52 PM, Landspeedrecord wrote:

> I having been trying to rearrange the time values of a MIDI file, i.e.
> rearrange the ordering of the notes while keeping all the other MIDI
> information intact.  I can load the MIDI into a seq object but from
> there I hit a brick wall.