Kieren MacMillan wrote:
Hi Alexander,
It's certainly easier for this special case, but the applyRhythm as is
gives far more freedom than your example.
If you have a rhythm like "4 4 8 8 4" in several voices, you can just say
rhythmA = "4 4 8 8 4"
sop = \applyRhythm #rhythmA { c d e f g | g f e d c }
alt = \applyRhythm #rhythmA { g f e d c | c d e f g }
and don't have to care at all about the rhythm while entering the notes.
Very nice!
I'm looking forward to hearing from others whether this is the
"cleanest" and most efficient implementation, or whether your fears
about "production-stage" limitations are warranted — until then, I'll
use it and consider myself a guinea pig. =)
Well then, guinea pig and all the others, :-)
here we go. Still, the functionality is what was there before (besides
support of newlines in the rhythmic pattern, which is very handy
sometimes), but I did some cleaning up and added a check to see whether
the durations are well-formed. So I'm not that suspicious of it anymore.
Still, I'm not a Schemer, so there may be some room left for
optimizations, and also some hidden errors for which I don't have the
intuition to guess them.
Anyway; feel free to test it, and perhaps it can be merged into the
cited LSR entry.
Cheers,
Alexander
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% applyRhythm
%%
%% 2009, Alexander Kobel (www.a-kobel.de)
%%
%% This program is free software. It comes without any warranty, to
%% the extent permitted by applicable law. You can redistribute it
%% and/or modify it under the terms of the Do What The Fuck You Want
%% To Public License, Version 2, as published by Sam Hocevar. See
%% http://sam.zoy.org/wtfpl/COPYING for more details.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% inspired by: http://lsr.dsi.unimi.it/LSR/Item?id=390
%% Thanks to the unknown contributor!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Version 1.1
%%
%% Changes to http://lsr.dsi.unimi.it/LSR/Item?id=390:
%%
%% - \makeRhythm => \applyRhythm
%% - reversed order of arguments for \applyRhythm
%% - name changes in the backend (no more camel case, e.g.)
%% - checking well-formedness of duration strings
%% - support *num/den arguments
%% - support rests and skips
%% - support additional (arbitrary) whitespace in the rhythm string
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% This should also work with older version,
%% probably up to <= 2.10.
%% Please report if this is the case.
\version "2.12.2"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Parsing single duration strings, like "4..*2/3"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(use-modules (ice-9 regex))
#(define duration-string-pattern "^[0-9]+\\.*(\\*[0-9]+)?(/[0-9]+)?$")
#(define (string->duration str)
(if (not (string-match duration-string-pattern str))
(begin
(display (string-append "warning: `" str "' does denote a valid
duration. "
"Using `128...*256'
instead.")
(current-error-port))
(ly:make-duration 7 3 256 1))
(let* (
(dot-index (string-index str #\.))
(nom-index (string-index str #\*))
(den-index (string-index str #\/))
(end-of-nom (or den-index (string-length str)))
(end-of-dots (or nom-index end-of-nom))
(end-of-length (or dot-index end-of-dots))
(length (ly:intlog2 (string->number (substring str 0
end-of-length))))
(dot-count (if dot-index
(- end-of-dots
dot-index)
0))
(nom (if nom-index
;; get rid of the "*"
(string->number (substring str (1+
nom-index) end-of-nom))
1))
(den (if den-index
;; get rid of the "/"
(string->number (substring str (1+
den-index) (string-length str)))
1)))
(ly:make-duration length dot-count nom den))))
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Parsing rhythm strings, like "4. 8 4 8.*8/9 16*4/3"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(define (string->duration-vector rhythm)
(let ((duration-string-list (string-tokenize rhythm)))
(list->vector (map string->duration duration-string-list))))
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Replace the duration of a chord by a duration
%% given as a specific element of a vector of durations
%%
%% Only apply to certain types of events (in particular,
%% not to multi measure rests)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(define (replace-chord-duration chord duration-vector index)
(begin
(if (or
(eq? 'NoteEvent (ly:music-property chord 'name))
(eq? 'RestEvent (ly:music-property chord 'name))
(eq? 'SkipEvent (ly:music-property chord 'name))
)
(set! (ly:music-property chord 'duration) (vector-ref
duration-vector index)))
chord))
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Apply the rhythm scheme of duration-vector at index
%% if music is a chord event; do nothing otherwise
%% Returns:
%% The transformed event and the index of the next duration
%% in the rhythm vector
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(define (replace-event-duration event duration-vector index)
(begin
(if (eq? 'EventChord (ly:music-property event 'name))
(begin
(map (lambda (chord) (replace-chord-duration chord
duration-vector index))
(ly:music-property event 'elements))
(set! index (modulo (1+ index) (vector-length
duration-vector)))))
(cons event index)))
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% The end-user function:
%% Apply rhythm (given as string) to music
%%
%% Example usage:
%% \applyRhythm "4 8 8 4 8.*8/9 16*4/3" { c d e f g a }
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
applyRhythm =
#(define-music-function (parser location rhythm music) (string? ly:music?)
(let (
(duration-vector (string->duration-vector rhythm))
(index 0)
)
(music-map
(lambda (event)
(let ((result (replace-event-duration event duration-vector
index)))
(begin
(set! index (cdr result))
(car result))))
music)))
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Test
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
applyRhythmTestCaseString = "
4... 32
8. 16 8.*8/9 16*4/3 "
applyRhythmTestCase = \new Score {
<<
\new Staff \applyRhythm \applyRhythmTestCaseString \relative c'
{ <c e> c <c e> c c c | R1 | c r r c r c }
\new Staff \repeat unfold 3 { \repeat unfold 4 \times 2/3 {
c''8 c'' c'' } \break }
>>
}
%% \score { \applyRhythmTestCase }
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