Re: color notehead according to absolute pitch

[Damian leGassick]

thanks jay

it doesn't handle b-sharp yet  - but other than that it's pretty  
compact for absolute pitch

apologies in advance to kenny for slightly hijacking the thread but...

my own needs are for (e.g.) all d-sharps/e-flats/e-naturals/f-flats to  
be red etc (parsing webern with hexatonic/octatonic scales for  
analysis students)

i can make it work by modifying your previous suggestion, along these  
lines:

#(define (pitch-to-color pitch)
        (cond
		((and (eqv? (ly:pitch-alteration pitch) 0) (eqv? (ly:pitch-notename  
pitch) 0)) (x11-color 'red))
		((and (eqv? (ly:pitch-alteration pitch) 1/2) (eqv? (ly:pitch- 
notename pitch) 0)) (x11-color 'green))
		((and (eqv? (ly:pitch-alteration pitch) -1/2) (eqv? (ly:pitch- 
notename pitch) 1)) (x11-color 'green))
		((and (eqv? (ly:pitch-alteration pitch) 0) (eqv? (ly:pitch-notename  
pitch) 2)) (x11-color 'red))
		((and (eqv? (ly:pitch-alteration pitch) 1/2) (eqv? (ly:pitch- 
notename pitch) 2)) (x11-color 'green))
		((and (eqv? (ly:pitch-alteration pitch) -1/2) (eqv? (ly:pitch- 
notename pitch) 3)) (x11-color 'red))
		((and (eqv? (ly:pitch-alteration pitch) 0) (eqv? (ly:pitch-notename  
pitch) 3)) (x11-color 'green))
		((and (eqv? (ly:pitch-alteration pitch) 1/2) (eqv? (ly:pitch- 
notename pitch) 4)) (x11-color 'red))
		((and (eqv? (ly:pitch-alteration pitch) 0) (eqv? (ly:pitch-notename  
pitch) 5)) (x11-color 'green))
		((and (eqv? (ly:pitch-alteration pitch) -1/2) (eqv? (ly:pitch- 
notename pitch) 5)) (x11-color 'red))
		((and (eqv? (ly:pitch-alteration pitch) 1/2) (eqv? (ly:pitch- 
notename pitch) 6)) (x11-color 'red))		
		((and (eqv? (ly:pitch-alteration pitch) 0) (eqv? (ly:pitch-notename  
pitch) 1)) (x11-color 'blue))
		((and (eqv? (ly:pitch-alteration pitch) 1/2) (eqv? (ly:pitch- 
notename pitch) 3)) (x11-color 'blue))
		((and (eqv? (ly:pitch-alteration pitch) -1/2) (eqv? (ly:pitch- 
notename pitch) 4)) (x11-color 'blue))
		((and (eqv? (ly:pitch-alteration pitch) 1/2) (eqv? (ly:pitch- 
notename pitch) 5)) (x11-color 'blue))
		((and (eqv? (ly:pitch-alteration pitch) -1/2) (eqv? (ly:pitch- 
notename pitch) 6)) (x11-color 'blue))
        )
)


but, as you can see it's hardly great programming style and somewhat  
error prone.

any further help would be hugely appreciated — other than the obvious,  
which is 'go and learn scheme! ' ;-) — as i've been struggling with  
this one for months now.

thanks again

damian





On 9 Aug 2008, at 05:12, Jay Anderson wrote:

> > If anyone can come up with a nice solution, this should definitely be
> > added to the LSR...
>
> I'm not sure this is a nice solution yet, but it is at least a little
> easier to manipulate the color mapping and it handles enharmonic
> spellings easily. Let me know what you think.
>
> -----Jay
>
> \version "2.11.54"
>
> %Association list of semitones from middle c to colors.
> #(define color-mapping
>  (list
>    (cons (ly:pitch-semitones (ly:make-pitch 0 0 0)) (x11-color 'blue))
>    (cons 2 (x11-color 'yellow))
>    (cons 3 (x11-color 'red))
>    (cons -1 (x11-color 'green))
>    (cons 5 (x11-color 'purple))
>    (cons 7 (x11-color 'cyan))
>    (cons 8 (x11-color 'ForestGreen))
>    ))
>
> #(define (pitch-to-color pitch)
>  (let ((color (assv (ly:pitch-semitones pitch) color-mapping)))
>    (if color (cdr color))))
>
> #(define (color-notehead grob)
>  (pitch-to-color (ly:event-property (ly:grob-property grob 'cause)  
> 'pitch)))
>
> \score
> {
>  \new Staff \relative c'
>  {
>    \override NoteHead #'color = #color-notehead
>    c8 b d dis ees f g aes
>  }
> }