This version detects major/minor key by counting the accidentals from
'pitch-alist and the tonic from 'tonic.
\version "2.18.2"
%{ P Gentry 25December 2014 12:36
;; Modified version of the LilyPond snippet enharmonic.ly (probably better as
enharmonic.ily)
;; This script will enharmonically spell a music object
;; Semi-tone intervals are dealt in accordance with the Key signature
;; If the Key is C Major or A Minor the first accidental encountered is chosen
as the preferred accidental
;; For other keys the preferred accidental is taken from the key signature
;; Minor keys are detected ie G major/E minor are treated the same.
;;It may not be elegant but it seems to work
%}
#(define k 0)
#(define nbuf 0)
#(define abuf 0)
#(define keysig 0)
# (define sharps 0)
# (define flats 0)
# (define ton 0)
#(define (count-sharps lst ns ton)
(if
(null? lst) (set! count-sharps sharps)
(begin
(if (eq? ns 0) set! (= ton (car(car lst))))
(if (> (cdr(assoc ns lst)) 0) (set! sharps ( + sharps 1 )) )
( set! ns (+ ns 1) )
(if (< ns 7) (count-sharps lst ns ton))
)
)
)
#(define (count-flats lst ns ton)
(if
(null? lst) (set! count-flats flats)
(begin
(if (eq? ns 0) set! (= ton (car(car lst))))
(if (< (cdr(assoc ns lst)) 0) (set! flats ( + flats 1 )) )
( set! ns (+ ns 1) )
(if (< ns 7) (count-flats lst ns ton))
)
)
)
#(define (naturalize-pitch p tonic key-list)
(define sharp-list '((0 . 0) (1 . 0) (2 . 1) (3 . 0) (4 . 0) (5 . 0) (6 .
1))) ; notes E# and B# may be changed to F and C
dependant on key
(define flat-list '((0 . 1) (1 . 0) (2 . 0) (3 . 1) (4 . 0) (5 . 0) (6 .
0))) ; notes Cb and Fb may be changed to B and E
dependant on key
(let ((o (ly:pitch-octave p))
(a (* 4 (ly:pitch-alteration p)))
(n (ly:pitch-notename p)))
;if keychange event detected determine if key contains flats s=1, naturals s=2
, or sharps s=3 ")
(cond ((eq? tonic 1 )
(begin
(set! sharps 0)
(count-sharps key-list 0 ton)
(set! flats 0)
(count-flats key-list 0 ton)
(if (and (eq? flats 0) (eq? sharps 0) (eq? n 0)) (display "C major"))
(if (and (eq? flats 0) (eq? sharps 0) (eq? n 5)) (display "A minor"))
(set! keysig 0) ;C Major & A minor contain no
accidentals
(set! k 0)
(if (> sharps 0) (set! keysig 3)) ; key contains sharps G D A E B F# C#
Major or E F# C# G# D# A# Minor
(if (> flats 0) (set! keysig 6)) ;key contains flats F Bb Eb Ab
Db Major or G C F Bb Eb Ab Minor
(if (eq? sharps 7 ) (set! keysig 1)) ;key C# Major or A# Minor
(if (eq? sharps 6 ) (set! keysig 2)) ;key F# Major or D# Minor
(if (eq? flats 7 ) (set! keysig 4)) ;key Cb Major or Ab Minor
(if (eq? flats 6 ) (set! keysig 5)) ;key Gb Major or Eb Minor
;; if not C major set preferred accidental type
(if (and (< keysig 4) (> keysig 0) (eq? k 0)) (set! k 2) ) ;; a sharp
key
(if (and (> keysig 3) (eq? k 0)) (set! k -2) ) ;; a
flat key
)
)
)
; if no keychange event naturalize the pitch
(set! nbuf n)
(set! abuf a)
; first remove double accidentals
; 1 deal with double sharps
(cond ((and (eq? tonic 0) (> a 2)) (begin (set! n (+ n 1)) (set! a (- a 4))
)))
(cond ((> n 6) (begin (set! n (- n 7)) (set! o(+ o 1)) )) )
(cond ((and (eq? (cdr(assoc nbuf sharp-list )) 1) (eq? abuf 4)) (begin (set! a
(+ a 2)) )))
; 2 deal with double flats
(cond ((and (eq? tonic 0) (< a -2)) (begin (set! n (- n 1)) (set! a(+ a 4)) )))
(cond ((< n 0) (begin (set! n(+ n 7)) (set! o(- o 1)) )))
(cond ((and (eq? (cdr(assoc nbuf flat-list )) 1) (eq? abuf -4)) (begin (set! a
(- a 2)) )))
;; if key C Major save first accidental as preferred type
(if (and (eq? tonic 0) (eq? keysig 0) (eq? k 0) (not (eq? a 0))) (set! k a)
)
;;deal with semi-tones Cb to B and Fb to E
; if keysig 6 or 0 and note is Cb or Fb make note B or E
(if (and (eq? tonic 0) (or (eq? keysig 6 ) (eq? keysig 0)) (< a -1) (eq?
(cdr(assoc n flat-list)) 1) )
(begin (set! a 0) (set! n (- n 1))))
; if keysig 4 and note is B or E make note Cb or Fb
(if (and (eq? tonic 0) (eq? keysig 4) (or (eq? n 2) (eq? n 6)) (eq? a 0))
(begin (set! a -2) (set! n (+ n 1))))
; if keysig 5 and note is E make note Fb
(if (and (eq? tonic 0) (eq? keysig 5) (eq? n 3) (eq? a 0))
(begin (set! a -2) (set! n (+ n 1))))
;;deal with semi-tones B# to C and E# toF
; if keysig 3 or 0 and note is E# or B# make note natural
(if (and (eq? tonic 0) (or (eq? keysig 3 ) (eq? keysig 0) ) (> a 1) (eq?
(cdr(assoc n sharp-list)) 1) )
(begin (set! a 0) (set! n (+ n 1))))
; if keysig 1 and note is C or F make note B# or E#
(if (and (eq? tonic 0) (eq? keysig 1) (or (eq? n 0) (eq? n 3)) (eq? a 0))
(begin (set! a 2) (set! n (- n 1))))
; if keysig 2 and note is F make note E#
(if (and (eq? tonic 0) (eq? keysig 2) (eq? n 3) (eq? a 0))
(begin (set! a 2) (set! n (- n 1))))
;; modify the octave if necessary
(if ( < n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
(if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
;take account of preferred flats
(cond ( (and (eq? tonic 0) ( < k 0 ) ( > a 0) (eq? (cdr(assoc n sharp-list
)) 0 )) (begin (set! a (* a -1)) (set! n (+ n 1)))))
(cond ( (and (eq? tonic 0) ( < k 0 ) ( > a 0) (eq? (cdr(assoc n sharp-list
)) 1 )) (begin (set! a 0) (set! n (+ n 1)))))
;take account of preferred sharps
(cond ((and (eq? tonic 0) ( > k 0 ) ( < a 0) (eq? (cdr(assoc n flat-list
)) 0 )) (begin (set! a (* a -1)) (set! n (- n
1)))))
(cond ((and (eq? tonic 0) ( > k 0 ) ( < a 0) (eq? (cdr(assoc n flat-list
)) 1 )) (begin (set! a 0) (set! n (- n
1)))))
;; modify the octave if necessary
(if ( < n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
(if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
(ly:make-pitch o n (/ a 4))
;; end scope of let
)
;; end scope of naturalize-pitch
)
#(define (naturalize music)
; get music data from the music file
(let ((es (ly:music-property music 'elements))
(e (ly:music-property music 'element))
(p (ly:music-property music 'pitch))
(t (ly:music-property music 'tonic))
(key-list (ly:music-property music 'pitch-alist)))
;write back to Lilypond
(if (pair? es)
(ly:music-set-property!
music 'elements
(map (lambda (x) (naturalize x)) es)))
(if (ly:music? e)
(ly:music-set-property!
music 'element
(naturalize e)))
; if lilypond pitch then naturalize before write back
(if (ly:pitch? p)
(begin
(set! p (naturalize-pitch p 0 key-list))
(ly:music-set-property! music 'pitch p)))
; if lilypond tonic then call naturalize but don't modify the pitch before
write back
(if (ly:pitch? t)
(begin
(set! t (naturalize-pitch t 1 key-list))
(ly:music-set-property! music 'tonic t)))
music )
)
naturalizeMusic =
#(define-music-function (parser location m)
(ly:music?)
(naturalize m))
Merry Christmas etc etc
Peter Gentry
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