pub fn pitch_class_distribution<'a>(
notes: impl IntoIterator<Item = (&'a [Pitch], FloatType)>,
) -> Option<[FloatType; 12]>Expand description
How long each pitch class sounds: for each note, its pitches and its
length in quarter notes, every pitch counting for the whole length.
Nothing when there are no notes. music21’s
_getPitchClassDistribution, a quarter tone rounding to the even class
as music21’s pitchClass does.