pitchtypes

A library for handling musical pitches and intervals in a systematic way. For other (and mostly compatible) implementations see:

• Pitches.jl (Julia)
• musicology-pitch (Haskell)
• purescript-pitches (Purescript)
• pitches.rs (Rust)

The main goals of this library are:

• providing types and operations (such as arithmetics, printing and parsing) for common types of pitches and intervals, (in particular spelled pitches and intervals, which are often difficult to handle),
• providing a generic interface for writing code that is agnostic to the specific pitch or interval types.

Installation

pip install pitchtypes

Minimal Example

import pitchtypes as pt

# write a generic function

def transposeby(pitches, interval):
    return [pitch + interval for pitch in pitches]

# use it with different pitch types

# spelled pitches correspond to written notes in Western notation
spelled_pitches = [pt.SpelledPitch(p)
                   for p in ["C4", "Eb4", "G#4"]]
print(transposeby(spelled_pitches, pt.SpelledInterval("m3:0"))

# spelled pitch classes work the same but they ignore octaves
spelled_pitch_classes = [pt.SpelledPitchClass(p)
                         for p in ["C", "Eb", "G#"]]
print(transposeby(spelled_pitches, pt.SpelledIntervalClass("m3"))

# enharmonic pitches correspond to keys on the piano
enharmonic_pitches = [pt.EnharmonicPitch(p)
                      for p in [60, 63, 68]]
print(transposeby(spelled_pitches, pt.EnharmonicInterval(3))

Output:

[Eb4, Gb4, B4]
[Eb, Gb, B]
[D#4, F#4, B4]

Old Example (delete/adapt?)

For instance, spelled pitch is handled correctly:

>>> from pitchtypes import SpelledPitchClass
>>> p1 = SpelledPitchClass("C#")
>>> p2 = SpelledPitchClass("Gb")
>>> i = p1 - p2
>>> type(i)
<class 'pitchtypes.datatypes.SpelledIntervalClass'>
>>> i
+AA4

Of course, you can also convert spelled pitches to their enharmonic equivalents:

>>> from pitchtypes import SpelledPitch, EnharmonicPitch
>>> spelled = SpelledPitch("C#4")
>>> enharmonic = spelled.convert_to(EnharmonicPitch)
>>> type(enharmonic)
<class 'pitchtypes.datatypes.EnharmonicPitch'>
>>> enharmonic.midi
61
>>> enharmonic.name('sharp')
C#4
>>> enharmonic.name('flat')
Db4

And used continuous log-frequency space (assuming twelve-tone equal temperament for enharmonic pitch):

>>> from pitchtypes import EnharmonicPitch, LogFreqPitch
>>> enharmonic = EnharmonicPitch("A4")
>>> logfreq = enharmonic.convert_to(LogFreqPitch)
>>> logfreq
440.Hz

For more examples, have a look at the Tutorial.ipynb!