rthm-seq-map/add-player [ Methods ]

[ Top ] [ rthm-seq-map ] [ Methods ]

DATE

 January 18th 2018, Heidhausen

DESCRIPTION

 Add a player to a rthm-seq-map. The data (3rd) argument defines the rthm-seq
 references (IDs) to be used for the new player. This is a very flexible
 argument: 
 
 If not given, then NIL will be added to the map, resulting in the new player
 not playing at all.

 If a single reference ID is given, then that will be used throughout each
 section of the map.

 If a list of references is given, then items will be popped out of the list
 sequentially and used for the new player. In this case the length of the
 list does not matter as if it's too long the last elements will simply be
 unused, and if it's too short then NIL will be returned when the list is
 exhausted, resulting in the new player not playing from that point
 onwards. The exception here is if the cycle (4th) argument is T, whereupon
 the list of references will be used circularly, restarting the list when the
 end is reached.

 Otherwise a function can be passed: this function should take four
 arguments: the rthm-seq-map object (which it can then analyse/query to make
 decisions); the full reference to the current (sub)section for which
 references should be provided; the number of references which are needed
 for this (sub)section; and the player being added. It must return a list of
 references for each given section. 

ARGUMENTS

 - the rthm-seq-map object
 - the new player to add (ID only: the same which will be referenced in the
   ensemble slot of a slippery-chicken object)

OPTIONAL ARGUMENTS

 - the rthm-seq-palette references to use for the new player. See above.
   Default NIL.
 - T or NIL to cycle the references. See above. Default NIL.

RETURN VALUE

 the same rthm-seq-map object but with the new player now added.

EXAMPLE

;; will use rthm-seq 1 throughout the piece
(add-player m 'cl 1)
;; will use 1 2 3 4 5 then nil thereafter
(add-player m 'ob '(1 2 3 4 5))
;; forcing a reference into a recursive rthm-seq-palette to be used just once
(add-player m 'db '((bass dense 1)))
;; forcing it to be used repeatedly
(add-player m 'db '((bass dense 1)) t)
;; a simple example with a function: rs1 for section 1, rs3 for section three
;;; otherwise rs1a 
(add-player m 'bsn #'(lambda (rsm section-ref num-refs player)
                             (ml (case section-ref
                                   (sec1 'rs1)
                                   (sec3 'rs3)
                                   (t 'rs1a))
                                 num-refs)))
;; db will be added but it won't play anything (unless references are added
;;; later but before make-slippery-chicken is called)
(add-player m 'db)

SYNOPSIS

(defmethod add-player ((rsm rthm-seq-map) player &optional data cycle)

rthm-seq-map/add-repeats [ Methods ]

[ Top ] [ rthm-seq-map ] [ Methods ]

DATE

 30-Dec-2010

DESCRIPTION

 Generate repeating sequences at given cycle points using recurring-event
 data. This process modifies the number of beats.

ARGUMENTS

 - A rthm-seq-map object.
 - A list of two-item lists of integers that determine the cycle
   pattern. This list will have the format of the recurring-event class's
   DATA slot (see recurring-event.lsp).
 - A list of two-item lists of integers that determine the number of repeats
   made (or references into the :repeats list). This list is also processed
   cyclically (i.e. the recurring-event class's RETURN-DATA-CYCLE slot).

OPTIONAL ARGUMENTS

 keyword arguments:
 - :section. The section map reference. Default = 1.
 - :repeats-indices. A list of the number of repeat bars returned by the
    cycle data (i.e. recurring-event class's RETURN-DATA slot). Generally
    this will remain NIL and the number of repeats will be expressed
    directly in the third argument, but it could be useful to use references
    into this list there instead, since the recurring-event class already
    makes this possible. Default = NIL.
 - :start. An integer that is the number of the bar/rthm-seq where the
   process is to begin. Default = 1.
 - :end. An integer that is the number of the bar/rthm-seq where the process
   is to end. NIL = process all bars/rthm-seqs. Default = NIL.
 - :print. T or NIL to indicate whether to print the rthm-seq ID and the
   number repetitions to the listener. T = print. Default = NIL.
 - :repeat-rest-seqs.  T or NIL to indicate whether sequences consisting of
   just rests should be repeated also.  This will need the :palette in order
   to work.  Default = T. 
 - :palette.  The rthm-seq-palette to check that sequences are not
   rest sequences, if about to repeat them and repeat-rest-seqs is NIL.

RETURN VALUE

 An integer that is the number of sequences added.

EXAMPLE

;;; Straightforward usage, additionally printing the DATA slot before and after
;;; applying the method
(let ((mrsm
       (make-rthm-seq-map 
        'rsm-test
        '((1 ((vn (1 2 3 2 1 3 1 3 2 3 1 2 1 3 1 3 2 1)))))
        :palette (make-rsp 
                  'rs-pal
                  '((1 ((((2 4) q e s s))))
                    (2 ((((2 4) e s s q))))
                    (3 ((((2 4) s s q e)))))))))
  (print (get-data-data '(1 vn) mrsm))
  ;; so there'll be a repeat after two events three times in a row, then after
  ;; three events twice in a row. The number of repeats will be 5 eight times
  ;; in a row, then 8 twice in a row.
  (add-repeats mrsm '((2 3) (3 2)) '((5 3) (8 2)))
  (print (get-data-data '(1 vn) mrsm)))

=>
(1 2 3 2 1 3 1 3 2 3 1 2 1 3 1 3 2 1) 
(1 2 3 3 3 3 3 2 1 1 1 1 1 3 1 1 1 1 1 3 2 3 3 3 3 3 3 3 3 1 2 1 1 1 1 1 1
 1 1 3 1 1 1 1 1 3 2 2 2 2 2 1) 

;;; Using the :start, :end, and :print arguments
(let ((mrsm
       (make-rthm-seq-map 
        'rsm-test
        '((1 ((vn (1 2 3 2 1 3 1 3 2 3 1 2 1 3 1 3 2 1)))))
        :palette (make-rsp 
                  'rs-pal
                  '((1 ((((2 4) q e s s))))
                    (2 ((((2 4) e s s q))))
                    (3 ((((2 4) s s q e)))))))))
  (print (get-data-data '(1 vn) mrsm))
  (add-repeats mrsm '((1 6) (2 6)) '((11 6) (23 3))
               :start 3
               :end 11
               :print t)
  (print (get-data-data '(1 vn) mrsm)))

=>
(1 2 3 2 1 3 1 3 2 3 1 2 1 3 1 3 2 1) 
2 x 11
1 x 11
3 x 11
1 x 11
3 x 11
2 x 11
1 x 23
(1 2 3 2 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 3 3 3 3 3 3 3 3 3 3 3 1
 1 1 1 1 1 1 1 1 1 1 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 3 1 1 1 1
 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 3 1 3 2 1) 

SYNOPSIS

(defmethod add-repeats ((rsm rthm-seq-map) repeat-every repeats &key
                        (repeat-rest-seqs t) palette
                        (section 1) repeats-indices (start 1) end print)

rthm-seq-map/add-repeats-simple [ Methods ]

[ Top ] [ rthm-seq-map ] [ Methods ]

DESCRIPTION

 Add repeats of a specified rthm-seq within the given rthm-seq-map object a
 specified number of times. 

ARGUMENTS

 - A rthm-seq-map object.
 - An integer that is the number of the rthm-seq (position within the
   rthm-seq-map) to be repeated.
 - An integer that is the number of times that rthm-seq is to be repeated.

OPTIONAL ARGUMENTS

 keyword arguments:
 - :section. An integer that is the ID of the section in which the repeat
   operation is to be performed.
 - :print. T or NIL to indicate whether to print the rthm-seq ID and the
   number repetitions to the listener. T = print. Default = NIL.

RETURN VALUE

 Always returns T.

EXAMPLE

;;; Print the DATA of the given rthm-seq-map, apply the method, and print again
;;; to see the difference.
(let ((mrsm
       (make-rthm-seq-map 
        'rsm-test
        '((1 ((vn (1 2 3 2 1 3 1 3 2 3 1 2 1 3 1 3 2 1)))))
        :palette (make-rsp 
                  'rs-pal
                  '((1 ((((2 4) q e s s))))
                    (2 ((((2 4) e s s q))))
                    (3 ((((2 4) s s q e)))))))))
  (print (get-data-data '(1 vn) mrsm))
  (add-repeats-simple mrsm 3 13)
  (print (get-data-data '(1 vn) mrsm)))

=>
(1 2 3 2 1 3 1 3 2 3 1 2 1 3 1 3 2 1) 
(1 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 1 3 1 3 2 3 1 2 1 3 1 3 2 1) 

SYNOPSIS

(defmethod add-repeats-simple ((rsm rthm-seq-map) start-seq repeats &key
                               (section 1) print)

rthm-seq-map/check-num-sequences [ Functions ]

[ Top ] [ rthm-seq-map ] [ Functions ]

DESCRIPTION

 Check to ensure that each player in each section of the given rthm-seq-map
 object has the same number of references as every other instrument. If not,
 drop into the debugger with an error.

 NB: This function is called automatically every time make-rthm-seq-map is
     called so it shouldn't generally be necessary for the user to call this
     method.  However, if the rthm-seq-map is changed somehow, it might be a
     good idea to recheck.

ARGUMENTS

 - A rthm-seq-map object.

RETURN VALUE

 Returns T if all players have the same number of references in each
 section, otherwise drops into the debugger with an error.

EXAMPLE

;;; Passes the test:
(let ((rsmt (make-rthm-seq-map 
             'rsm-test
             '((sec1 ((vn (rs1a rs3a rs2a))
                      (va (rs1b rs3b rs2b))
                      (vc (rs1a rs3b rs2a))))
               (sec2 ((vn (rs1a rs2a rs1a))
                      (va (rs1a rs2a rs1b))
                      (vc (rs1a rs2b rs1a))))
               (sec3 ((vn (rs1a rs1a rs3a))
                      (va (rs1a rs1a rs3b))
                      (vc (rs1a rs1b rs3a))))
               (sec4 ((vn (rs1a rs1a rs1a))
                      (va (rs1a rs1a rs1b))
                      (vc (rs1a rs1b rs1a))))))))
  (check-num-sequences rsmt))

=> T

;;; Doesn't pass the test; drops into debugger with an error.
(let ((rsmt (make-rthm-seq-map 
             'rsm-test
             '((sec1 ((vn (rs1a rs3a rs2a))
                      (va (rs1b rs3b))
                      (vc (rs1a rs3b rs2a))))
               (sec2 ((vn (rs1a))
                      (va (rs1a rs2a rs1b))
                      (vc (rs1a rs2b rs1a))))
               (sec3 ((vn (rs1a rs3a))
                      (va (rs1a))
                      (vc (rs1a rs1b rs3a))))
               (sec4 ((vn (rs1a))
                      (va (rs1a rs1a rs1b))
                      (vc (rs1a rs1a))))))))
  (check-num-sequences rsmt))

=>
rthm-seq-map::check-num-sequences: In rthm-seq-map RSM-TEST-5, instrument VA: 
Each instrument must have the same number of sequences for any given section: 
(RS1B RS3B)
   [Condition of type SIMPLE-ERROR]

SYNOPSIS

(defun check-num-sequences (rsm)

rthm-seq-map/get-map-refs [ Methods ]

[ Top ] [ rthm-seq-map ] [ Methods ]

DATE

 29-Dec-2010

DESCRIPTION

 Return the list of rthm-seq-palette references for the given player and
 section.

ARGUMENTS

 - A rthm-seq-map object.
 - The ID of the section in which the references are sought.
 - The ID of the player for whom the references are sought.

RETURN VALUE

 A list of references (each of which might also  be a list).

EXAMPLE

(let ((rsmt (make-rthm-seq-map 
             'rsm-test-5
             '((sec1 ((vn (rs1 rs3 rs2))
                      (va (rs2 rs3 rs1))
                      (vc (rs3 rs1 rs2))))
               (sec2 ((vn (rs1 rs2 rs1))
                      (va (rs2 rs1 rs3))
                      (vc (rs1 rs3 rs3))))
               (sec3 ((vn (rs1 rs1 rs3))
                      (va (rs1 rs3 rs2))
                      (vc (rs3 rs2 rs3)))))
             :palette (make-rsp 
                       'rs-pal
                       '((rs1 ((((2 4) q e s s))))
                         (rs2 ((((2 4) e s s q))))
                         (rs3 ((((2 4) s s q e)))))))))
  (get-map-refs rsmt 'sec3 'vc))

=> (RS3 RS2 RS3)

SYNOPSIS

(defmethod get-map-refs ((rsm rthm-seq-map) section player)

rthm-seq-map/get-time-sig-ral [ Methods ]

[ Top ] [ rthm-seq-map ] [ Methods ]

DESCRIPTION

 Collate the IDs of all rthm-seq objects in a given rthm-seq-map into groups
 based on identical time signatures and return this as a
 recursive-assoc-list object that has the same structure of the map. 

 Instead of having the list of rthm-seq references for each
 section/instrument, the method returns an assoc-list whose keys are the
 time-sig tags, with the corresponding data being circular-sclists of
 rthm-seq IDs.  

 The result is a recursive-assoc-list for each instrument/section that can
 be queried to find the rthm-seq refs of all rthm-seqs that share the same
 bar/time-sig structure; e.g., all those that have a 2/4 bar followed by a
 3/4 bar etc.

ARGUMENTS

 - A rthm-seq-map object.
 - A rthm-seq-palette object.

RETURN VALUE

 A recursive-assoc-list object.

EXAMPLE

(let* ((mini
        (make-slippery-chicken
         '+mini+
         :ensemble '(((sax (alto-sax :midi-channel 1))))
         :set-palette '((1 ((c2 d2 g2 a2 e3 fs3 b3 cs4 fs4 gs4 ds5 f5 bf5)))) 
         :set-map '((1 (1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1)))
         :rthm-seq-palette '((1 ((((4 4) h q e s s) ((2 4) h))))
                             (2 ((((4 4) h q e s s))))
                             (3 ((((4 4) h q e s s))))
                             (4 ((((4 4) h q q) ((2 4) q q))))
                             (5 ((((4 4) h q e s s))))
                             (6 ((((4 4) h q q) ((2 4) q q)))))
         :rthm-seq-map '((1 ((sax (1 2 3 5 2 4 6 2 3 1 3 2 3 2 1 3 2)))))))
       (tsral (get-time-sig-ral (rthm-seq-map mini) (rthm-seq-palette mini))))
  (get-data-data 1 tsral))

=> 
RECURSIVE-ASSOC-LIST: recurse-simple-data: T
                      num-data: 1
                      linked: T
                      full-ref: (1)
ASSOC-LIST: warn-not-found T
CIRCULAR-SCLIST: current 0
SCLIST: sclist-length: 1, bounds-alert: T, copy: T
LINKED-NAMED-OBJECT: previous: NIL, this: NIL, next: NIL
NAMED-OBJECT: id: "sub-ral-of-+MINI+-RTHM-SEQ-MAP", tag: NIL, 
data: (
ASSOC-LIST: warn-not-found T
CIRCULAR-SCLIST: current 0
SCLIST: sclist-length: 2, bounds-alert: T, copy: T
LINKED-NAMED-OBJECT: previous: NIL, this: (1 SAX), next: NIL
NAMED-OBJECT: id: SAX, tag: NIL, 
data: (
CIRCULAR-SCLIST: current 0
SCLIST: sclist-length: 3, bounds-alert: T, copy: T
LINKED-NAMED-OBJECT: previous: NIL, this: NIL, next: NIL
NAMED-OBJECT: id: "0404-0204", tag: NIL, 
data: (4 6 1)
**************

       
CIRCULAR-SCLIST: current 0
SCLIST: sclist-length: 3, bounds-alert: T, copy: T
LINKED-NAMED-OBJECT: previous: NIL, this: NIL, next: NIL
NAMED-OBJECT: id: "0404", tag: NIL, 
data: (5 3 2)
**************
)
**************
)
**************

SYNOPSIS

(defmethod get-time-sig-ral ((rsm rthm-seq-map) (rsp rthm-seq-palette))

rthm-seq-map/make-rthm-seq-map [ Functions ]

[ Top ] [ rthm-seq-map ] [ Functions ]

DESCRIPTION

 Make a rthm-seq-map object.

ARGUMENTS

 - The ID of the rthm-seq-map object to be made.
 - A list of nested lists, generally taking the form 
   '((section1 ((player1 (rthm-seq ids))
                (player2 (rthm-seq ids))
                (etc... (etc...))))
     (section2 ((player1 (rthm-seq ids))
                (player2 (rthm-seq ids))
                (etc...)))
     (etc...))

OPTIONAL ARGUMENTS

 keyword arguments:
 - :palette. A palette object or NIL. If a palette object is specified or
   defined here, it will be automatically bound to the given rthm-seq-map
   object. Default = NIL.
 - :warn-not-found. T or NIL to indicate whether a warning is printed when
   an index which doesn't exist is used for look-up.  
   T = warn. Default = NIL.
 - :replacements. A list of lists in the format 
   '(((1 2 vla) 3 20b) ((2 3 vln) 4 16a)) that indicate changes to
   individual elements of lists within the given rthm-seq-map object. (Often
   rthm-seq-map data is generated algorithmically but individual elements of
   the lists need to be changed.)  Each such list indicates a change, the
   first element of the list being the reference into the rthm-seq-map (the
   vla player of section 1, subsection 2 in the first example here), the
   second element is the nth of the data list for this key to change, and
   the third is the new data. Default = NIL.
 - :recurse-simple-data. T or NIL to indicate whether to recursively
   instantiate a recursive-assoc-list in place of data that appears to be a
   simple assoc-list (i.e. a 2-element list). If NIL, the data of 2-element
   lists whose second element is a number or a symbol will be ignored,
   therefore remaining as a list. For example, this data would normally
   result in a recursive call: (y ((2 23) (7 28) (18 2))).  
   T = recurse. Default = T.

RETURN VALUE

 A rthm-seq-map object.

EXAMPLE

;;; Straightforward usage
(make-rthm-seq-map 'rsm-test
                    '((1 ((vn (1 2 3 4))
                          (va (2 3 4 1))
                          (vc (3 4 1 2))))
                      (2 ((vn (4 5 6))
                          (va (5 6 4))
                          (vc (6 4 5))))
                      (3 ((vn (7 8 9 1 2))
                          (va (8 9 1 2 7))
                          (vc (9 1 2 7 8))))))

=>

RTHM-SEQ-MAP: num-players: 3 
              players: (VA VC VN)
SC-MAP: palette id: NIL
RECURSIVE-ASSOC-LIST: recurse-simple-data: T
                      num-data: 9
                      linked: NIL
                      full-ref: NIL
ASSOC-LIST: warn-not-found NIL
CIRCULAR-SCLIST: current 0
SCLIST: sclist-length: 3, bounds-alert: T, copy: T
LINKED-NAMED-OBJECT: previous: NIL, this: NIL, next: NIL
NAMED-OBJECT: id: RSM-TEST, tag: NIL, 
data: (
[...]

;;; An example using the :replacements argument and binding directly to a
;;; specified rthm-seq-palette object.
(make-rthm-seq-map 'rsm-test
                   '((1 ((vn (1 2 3 4))
                         (va (2 3 4 1))
                         (vc (3 4 1 2))))
                     (2 ((vn (4 5 6))
                         (va (5 6 4))
                         (vc (6 4 5))))
                     (3 ((vn (7 8 9 1 2))
                         (va (8 9 1 2 7))
                         (vc (9 1 2 7 8)))))
                   :palette (make-rsp 
                             'rs-pal
                             '((rs1 ((((2 4) q e s s))))
                               (rs2 ((((2 4) e s s q))))
                               (rs3 ((((2 4) s s q e))))))
                   :replacements '(((1 vn) 2 7)
                                   ((2 va) 1 1)
                                   ((3 vc) 1 0)))

=>
RTHM-SEQ-MAP: num-players: 3 
              players: (VA VC VN)
SC-MAP: palette id: RS-PAL
RECURSIVE-ASSOC-LIST: recurse-simple-data: T
                      num-data: 9
                      linked: NIL
                      full-ref: NIL
ASSOC-LIST: warn-not-found NIL
CIRCULAR-SCLIST: current 0
SCLIST: sclist-length: 3, bounds-alert: T, copy: T
LINKED-NAMED-OBJECT: previous: NIL, this: NIL, next: NIL
NAMED-OBJECT: id: RSM-TEST, tag: NIL, 
data: (
[...]

SYNOPSIS

(defun make-rthm-seq-map (id rsm &key (palette nil) (warn-not-found nil)
                                      (replacements nil)
                                      (recurse-simple-data t))

rthm-seq-map/rsm-count-notes [ Functions ]

[ Top ] [ rthm-seq-map ] [ Functions ]

DESCRIPTION

 Returns the number of notes in the given rthm-seq-map object for the
 specified player and rthm-seq-palette.

ARGUMENTS

 - A rthm-seq-map object.
 - The ID of the player whose notes are to be counted.
 - The rthm-seq-palette object whose rthm-seq object IDs are referred to by
   the given rthm-seq-map object.

OPTIONAL ARGUMENTS

 - T or NIL to indicate whether to count just the number of notes that need
   new events (i.e., not counting tied notes; also not counting chords,
   since chords need only one event) or the total number of notes in that
   player's part in the score. T = count just attacked notes. Default = T. 

RETURN VALUE

 Returns an integer that is the number of notes counted.

EXAMPLE

(let ((rsmt (make-rthm-seq-map 
             'rsm-test
             '((sec1 ((vn (rs1 rs3 rs2))
                      (va (rs2 rs3 rs1))
                      (vc (rs3 rs1 rs2))))
               (sec2 ((vn (rs1 rs2 rs1))
                      (va (rs2 rs1 rs3))
                      (vc (rs1 rs3 rs3))))
               (sec3 ((vn (rs1 rs1 rs3))
                      (va (rs1 rs3 rs2))
                      (vc (rs3 rs2 rs3)))))))
      (rspt (make-rsp 
             'rs-pal
             '((rs1 ((((2 4) q (e) s s))))
               (rs2 ((((2 4) e +s (s) q))))
               (rs3 ((((2 4) (s) s +q e))))))))
  (print (rsm-count-notes rsmt 'vn rspt))
  (print (rsm-count-notes rsmt 'va rspt nil)))

=> 
23 
27

SYNOPSIS

(defun rsm-count-notes (rthm-seq-map player palette &optional (just-attacks t))

rthm-seq-map/set-map-refs [ Methods ]

[ Top ] [ rthm-seq-map ] [ Methods ]

DATE

 30-Dec-2010

DESCRIPTION

 Change the reference IDs of the specified rthm-seq objects in the given
 rthm-seq-map object.

ARGUMENTS

 - A rthm-seq-map object.
 - The ID of the section in which references are to be set.
 - The ID of the player for whom the references are to be set.
 - A list of the new rthm-seq IDs (references) 

RETURN VALUE

 Returns the modified named object whose ID is the specified player.

EXAMPLE

(let ((rsmt (make-rthm-seq-map 
             'rsm-test-5
             '((sec1 ((vn (rs1 rs3 rs2))
                      (va (rs2 rs3 rs1))
                      (vc (rs3 rs1 rs2))))
               (sec2 ((vn (rs1 rs2 rs1))
                      (va (rs2 rs1 rs3))
                      (vc (rs1 rs3 rs3))))
               (sec3 ((vn (rs1 rs1 rs3))
                      (va (rs1 rs3 rs2))
                      (vc (rs3 rs2 rs3)))))
             :palette (make-rsp 
                       'rs-pal
                       '((rs1 ((((2 4) q e s s))))
                         (rs2 ((((2 4) e s s q))))
                         (rs3 ((((2 4) s s q e)))))))))
  (set-map-refs rsmt 'sec2 'vc '(rs2 rs3 rs2)))

=> 
NAMED-OBJECT: id: VC, tag: NIL, 
data: (RS2 RS3 RS2)

SYNOPSIS

(defmethod set-map-refs ((rsm rthm-seq-map) section player new-refs)

sc-map/rthm-seq-map [ Classes ]

[ Top ] [ sc-map ] [ Classes ]

NAME

 rthm-seq-map

 File:             rthm-seq-map.lsp

 Class Hierarchy:  named-object -> linked-named-object -> sclist -> 
                   circular-sclist -> assoc-list -> recursive-assoc-list ->
                   sc-map -> rthm-seq-map

 Version:          1.0.10

 Project:          slippery chicken (algorithmic composition)

 Purpose:          Implementation of the rthm-seq-map class which maps
                   references to rthm-seq objects for the players in the
                   piece.  Extensions to the sc-map superclass are the
                   collection of all the players in the piece and a
                   check to make sure that each list each instrument has the
                   same number of rthm-seq references for each section. 

                   Instances of this class must declare sections and
                   players so if the piece is in one section, give it
                   the label 1 or whatever, e.g.

                   '((1
                      ((vln (2 20 1 9 10 22 16 25 6 14 21 17 4 9 13 2))
                       (vla (2 23 3 7 13 22 19 3 8 12 23 14 2 10 15 4))
                       (vc (2 21 3 12 11 22 16 1 8 17 23 20 24 9 12 2)))))


 Author:           Michael Edwards: m@michael-edwards.org

 Creation date:    July 28th 2001

 $$ Last modified:  15:30:06 Fri Aug  9 2019 CEST

 SVN ID: $Id$