filterChordChanges

\version "2.19.82"

#(define (filterChanges music)
   (let ((es (ly:music-property music 'elements))
         (e (ly:music-property music 'element))
         (p (ly:music-property music 'pitch)))
     (if (and
          (pair? es)
          (not
           (music-is-of-type? music 'event-chord)))
         (ly:music-set-property!
          music 'elements
          (map (lambda (x) (filterChanges x)) es)))
     (if (ly:music? e)
         (ly:music-set-property!
          music 'element
          (filterChanges e)))
     (if (and (not (pair? es))
              (music-is-of-type? music 'event-chord))
         (set! music (make-music
                        'RestEvent
                        'duration
                        (ly:music-property music 'duration))))

     (if (ly:pitch? p)
         (begin
           (set! music (make-music
                        'RestEvent
                        'duration
                        (ly:music-property music 'duration)))))
     music))

filterChordChanges =
#(define-music-function (parser location m)
     (ly:music?)
   (filterChanges m))

music = { d \chordmode { d:m/a } f, q d q f, q  e, \chordmode { e:7^5/gis }  gis, q e, q gis, q }

\new Staff { \clef "bass"
  <<
    \new ChordNames {
      \set noChordSymbol = ""
      \filterChordChanges \music
  }
  \music
  >>
}