Other inversions of dominant 7ths

[malcolmsailor]

music21 version

8.0.0a9

Problem summary

According to the docs, "Dominant 7ths can be specified by putting d7 at end". Naively, I expected "d43" to then be a dominant 7th in 43 position. It isn't, but we can get that with "43d7". Perhaps a note of clarification in the docs could be useful? Or just changing the behavior for "d43"?

Steps to reproduce

>>> from music21 import roman
>>> RN = roman.RomanNumeral
>>> RN("IV7").pitches
(<music21.pitch.Pitch F4>, <music21.pitch.Pitch A4>, <music21.pitch.Pitch C5>, <music21.pitch.Pitch E5>)
>>> RN("IVd7").pitches
(<music21.pitch.Pitch F4>, <music21.pitch.Pitch A4>, <music21.pitch.Pitch C5>, <music21.pitch.Pitch E-5>)
>>> RN("IV43").pitches
(<music21.pitch.Pitch C4>, <music21.pitch.Pitch E4>, <music21.pitch.Pitch F4>, <music21.pitch.Pitch A4>)
>>> RN("IVd43").pitches # I naively expected C-Eb-F-A
(<music21.pitch.Pitch C4>, <music21.pitch.Pitch E4>, <music21.pitch.Pitch F4>, <music21.pitch.Pitch A4>)
>>> RN("IV43d7").pitches # OK
(<music21.pitch.Pitch F4>, <music21.pitch.Pitch E-5>, <music21.pitch.Pitch A5>, <music21.pitch.Pitch B5>)

[malcolmsailor]

Actually I just noticed that the last pitch of RN("IV43d7").pitches is B, which is not what I expected. So maybe there is no way to use "d" to change an inversion to a dominant 7th?

[malcolmsailor]

It looks to me like this could be solved by matching patterns beyond "d7" here:

music21/music21/roman.py

Line 2337 in de1be4b

elif workingFigure.endswith('d7'):

A regex that matches d followed by the various 7th chord patterns (7, 65, 43, 42, 2... others?) should do it. I could implement this if you like.