Re: custom replace/map of one set of pitches to another

[Michael Winter]

Thank you Valentin for this solution and the following explanation why it is likely safer.

All responses have been much appreciated.

Best,

Michael

Sep 1, 2023, 00:15 by valentin@petzel.at:

Hi Michael,

some time ago I created a function for exactly that for a stackexchange

question:

https://music.stackexchange.com/questions/127175/lilypond-transpose-a-sequence-to-modes-with-different-intervallic-structure

Essentially it introduces a function to map one scale to another, and it does

so by basepitch to retain alteration. One could easily adapt this function to

match by base pitch and alteration:

transposePitchClasses =

#(define-music-function (scaleA scaleB music) (ly:music? ly:music? ly:music?)

(let* ((scaleA (ly:music-property scaleA 'elements))

(scaleB (ly:music-property scaleB 'elements))

(scaleA (map (lambda (x) (ly:music-property x 'pitch)) scaleA))

(scaleB (map (lambda (x) (ly:music-property x 'pitch)) scaleB))

(classesA (map (lambda (p) (cons (ly:pitch-notename p) (ly:pitch-

alteration p))) scaleA)))

(map-some-music

(lambda (m)

(let ((p (ly:music-property m 'pitch)))

(if (not (null? p))

(let* ((nn (ly:pitch-notename p))

(oct (ly:pitch-octave p))

(alt (ly:pitch-alteration p))

(pos (list-index (lambda (x) (and (= (car x) nn) (= (cdr x)

alt))) classesA)))

(if pos

(let* ((p2 (list-ref scaleA pos))

(oct2 (ly:pitch-octave p2))

(p3 (list-ref scaleB pos))

(new-pitch (ly:pitch-transpose p3 (ly:make-pitch (-

oct oct2) 0))))

(ly:music-set-property! m 'pitch new-pitch)))

m)

#f)))

music)

music))

\transposePitchClasses {d fih g aih} {dih f gis a}

{ c' cis' d' dis' f' fih' fis' g' a' aih' }

Am Donnerstag, 31. August 2023, 12:53:26 CEST schrieb Michael Winter via

LilyPond user discussion:

I would like to do something (hopefully simple), which is basically a custom

find and replace for a set of notes in an entire score.

For example {c cis d dis fih g aih} -> {c cis dih dis f gis a}

So basically on arbitrary list of pitches / scale to another.

Is this possible without writing a custom function. If not, any hints on how

to tackle the problem would be much appreciated. Thanks in advance.

-Michael