Before I roll up my sleeves and build something that might already exist --

Is there already an abstraction somewhere for diatonic scale degree mapping? cf. http://doc.sccode.org/Classes/SimpleNumber.html#-degreeToKey

degreeToKey is relatively easy (basically wrapped indexing into an array, with octave displacement).

The inverse operation keyToDegree is a little trickier -- if somebody has already done it, I would rather not reinvent the wheel.

Thanks,
hjh

@ddw_music I am not a musician so...... but this might be a starting point...... rtc library and uses other "extended" libraries. [list-len] you can change to [list length] for vanilla....... and [bassemu~] is just part of the final midi "player" and so should be replaceable scale.zip
I know [list-idx] can be replaced.
If you check it out in extended and it looks like it is useful then I can work to make it vanilla compatible today.... there are quite a few other objects to replace.
David.

OK, thanks.

hjh

@ddw_music You can have a quick look at pdmtl abstraction:
https://github.com/aalex/pdmtl

Look for all musical.* might have something there that would help you a bit?

@ddw_music It should be easy to implement that as long both scales have the same length and it is clear what should happen with notes that are not part of the first scale (i.e. skip them, map them to the scale or keep the distance to the next lower note of the scale).

Implementation would also be easier if the input and output is Midi notes and the scales could have a format like [0 2 4 5 7 9 11( for major, i.e. a list of whole/half tone steps.

If you have trouble building this, i could give it a shot, if you could say what conditions of the above could be met.

@ddw_music Well, i haven't really understood what keyToDegree does in your example. Anyhow, here is an abstraction that maps notes to a specific scale:

https://forum.pdpatchrepo.info/topic/11722/mscale-transpose-notes-according-to-given-scale-and-root

It does not however map the degrees of one scale to another, so it does not for example map the dominant of one scale to the dominant of another scale. Therefor two scales would have to be given (source and destination) what keyToDegree doesn't seem to do.

[mscale] only takes any note and maps it to the nearest note of a given scale.

There is actually a difference between SC's 'degree' and mscale.

[mscale] is more like an analog modular quantizer -- put in chromatic data, and it gets rounded off to the scale.

What I was looking for is a diatonic data representation: scale degrees 0 1 2 3 4 5 6 7 map onto major scale chromatic semitones 0 2 4 5 7 9 11 12. That way, a root position triad is always note, note+2, note+4 and this becomes major, minor or diminished at the time of mapping.

Diatonic transposition is really hard when the data are chromatic. It's really easy when the data are diatonic.

degreeToKey was as easy as I expected. keyToDegree isn't critical for me at the moment, so I'll deal with that later.

hjh

degree2key.pd