coloring noteheads different depending on parts

[takmi ikeda]

i'd like to change coloring by argument. have you any idea?

\version "2.16.0"

#(define-public ((color-notehead . nnn) grob)

   (define color-mapping
     (vector
      (list
       (cons (ly:make-pitch 0 0 0) (rgb-color 1 0 0))
       (cons (ly:make-pitch 0 4 0) (rgb-color 0 1 0))
       )
      (list
       (cons (ly:make-pitch 0 1 0) (rgb-color 0 1 1))
       (cons (ly:make-pitch 0 5 0) (rgb-color 1 0 1))
       )
      )
     )

   (define (pitch-to-color pitch)
     (let*
      (
       (vvv (vector-ref color-mapping num)) ;it does not works.
       ;(vvv (vector-ref color-mapping 0)) ;it works.
       (ccc (assoc pitch vvv))
       )
      (if ccc
          (cdr ccc))
      )
     )

   (pitch-to-color
    (ly:event-property (event-cause grob) 'pitch))
   )

aaa = \relative c' { c8 d e f g a b c }

\score {
  <<
    \new Staff <<
      \override Staff.NoteHead #'color = #(color-notehead 0)
      \aaa
    >>
    \new Staff <<
      \override Staff.NoteHead #'color = #(color-notehead 1)
      \aaa
    >>
  >>
}