Splitting chords: Difference between revisions

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-This snippet is a 2009 contribution by Gilles Thibault in [https://lists.gnu.org/archive/html/lilypond-user/2009-01/msg00685.html lilypond-user]. It splits a chord sequence into two separated voices: the first one built on the first note (usually the lowest) of every chord and the other on the remaining notes. It works well in 2.24.4 and even in 2.25.35. I find it very useful. It also preserves articulations and slurs. The only drawback: it doesn't work if you use «q» to repeat last chord.
+This snippet is a 2009 contribution by Gilles Thibault in [https://lists.gnu.org/archive/html/lilypond-user/2009-01/msg00685.html lilypond-user]. It provides two functions to split a chord sequence into two separate voices, also preserving articulations and slurs: <code>\keepOnlyFirstNote</code> extracts the first note (as given in the input; this is usually the lowest one) of every chord, and <code>\deleteFirstNote</code> collects the remaining notes.
+Note that these functions don't support <code>q</code> to repeat the last chord.
 <lilypond version="2.24">
+#(define (has-duration? music)
+   (ly:duration? (ly:music-property music 'duration)))
+#(define (not-has-duration? music)
+   (not (has-duration? music)))
+keepOnlyFirstNote =
+#(define-music-function (music) (ly:music?)
+   (music-map
+    (lambda (evt)
+      (when (eq? 'EventChord (ly:music-property evt 'name))
+ 	(let ((elts (ly:music-property evt 'elements)))
+ 	  (when (has-duration? (car elts))
+ 	    (ly:music-set-property!
+ 	     evt 'elements
+ 	     (cons (car elts)
+ 		   (filter not-has-duration? (cdr elts)))))))
+      evt)
+    music))
+deleteFirstNote =
+#(define-music-function (music) (ly:music?)
+   (music-map
+    (lambda (evt)
+      (when (eq? 'EventChord (ly:music-property evt 'name))
+ 	(let ((elts (ly:music-property evt 'elements)))
+          (when (has-duration? (car elts))
+            (ly:music-set-property! evt 'elements  (cdr elts)))))
+      evt)
+    music))
+music = \relative c' {
+  <c e>4-> <d f>( <b g'>) <c e>-. g2 c2
+}
+\markup { Music with chords }
+\new Staff \music
- #(define (has-duration? music)
+\markup { Music split into two staves }
- (ly:duration? (ly:music-property music 'duration)))
+<<
+  \new Staff \deleteFirstNote \music
- #(define (not-has-duration? music)
+  \new Staff \keepOnlyFirstNote \music
- (not (has-duration? music)))
+>>
- keepsOnlyFirstNote = #(define-music-function (parser location music) (ly:music?)
- (music-map
-  (lambda (evt)
-   (if (eq? 'EventChord (ly:music-property evt 'name))
-      (let ((elts (ly:music-property evt 'elements)))
-       (if (has-duration? (car elts))
-            (ly:music-set-property! evt 'elements (cons
-                 (car elts)
-                 (filter not-has-duration? (cdr elts)))))))
-  evt)
- music))
- deleteFirstNote = #(define-music-function (parser location music) (ly:music?)
- (music-map
-  (lambda (evt)
-   (if (eq? 'EventChord (ly:music-property evt 'name))
-      (let ((elts (ly:music-property evt 'elements)))
-           (if (has-duration? (car elts))
-                (ly:music-set-property! evt 'elements  (cdr elts)))))
-  evt)
- music))
- music =\relative c' {
- <c e>4-> <d f>( <b g'>) <c e>-. g2 c2
- }
- \markup { Music with chords }
- \new Staff \music
- \markup { Music splitted in 2 staffs }
- <<
-   \new Staff \deleteFirstNote \music
-   \new Staff \keepsOnlyFirstNote \music
- >>
 </lilypond>
 [[category:Chords]]
 [[category:Scheme]]
 [[category:Really cool]]