Algorithmic composition tools

A 'pitch set' is a set of pitches (i.e. MIDI pitch numbers) that's invariant under shifting by an octave. Examples include scales and chords.

Class PitchSet represents a pitch set. Its constructor is:

PitchSet(
    pitch_offsets: list[int],
    root: int,
    probs: list[float] = None
)

pitch_offsets is a list of pitch offsets (0..11). For example, the offsets for a major scale are [0,2,4,5,7,9,11].

root is a pitch corresponding to offset 0.

probs is a list of relative probabilities of choosing each of the pitch offsets in the random note selection functions described below. If not specified, weights are identical.

PitchSet.rnd_uniform(self, lo: int, hi: int)

returns a pitch in the set between lo and hi inclusive, or -1 if there are none. The pitch is chosen randomly, with probabilities proportional to the probs values.

PitchSet.rnd_normal(mean: float, stddev: float, maxsigma: float)

return a random pitch in the set from a distribution with the given mean and stddev, truncated to the given max stddev, with probabilities proportional to the probs values.

PitchSet.gt(p: int, index: int = -1)

returns the lowest pitch in the set that is greater than p and has the given offset index (if specified). Returns -1 if there is none.

PitchSet.ge(p: int, index: int = -1)

Same, but greater than or equal.

PitchSet.lt(p: int, index: int = -1)

Same, but less than.

PitchSet.le(p: int, index: int = -1)

Same, but less than or equal.