Roman Numeral Notation

[kevinhongw]

It would be nice to have a function to output the roman numeral notation of the chords. A lot of musicians I worked with prefer numeral notation. I could try to create a PR when I have time.

[MikeMijnheer]

I'm interested in this too! Did you implement it already by any chance @KevinHong913?

[OskarsPakers]

How would you expect the API to be? Conversion to Roman notation would not be a transposition so .transpose() method would not make sense, right? Or would something like this make sense?

 Transposer.transpose(
"G        C           Am7            C        D7       G" +
"Saying I love you is not the words I want to hear from you").toNumericNotation().toString()

'V       I          vi7            I       II7       V' +
'Saying I love you is not the words I want to hear from you'

[contributor]

I would call the method toRomanNumerals() @OskarsPakers your example correctly converts to roman numerals. If can be more tricky to convert non-diatonic chords, for example Bb is common to the key of C - it would be VIIb. I don't recall ever seeing sharps in roman numerals notation, only flats (but I'm not musician)

[contributor]

The hardest thing could be chord inversions (slash chords). Notation quite complex, for the first version we could just throw not implemented error