pymusictheory

pymusictheory is a Python library for performing calculations with musical notes. It provides tools to work with notes, intervals, and chords, both in the context of octaves and without. This library is useful for music theory analysis, algorithmic composition, and other musical applications.

Key features:

• Correctly returning double accidentals when adding intervals to notes. Example: B# + M3 = D##

Not implemented:

• Adding intervals to notes with double accidentals. For example, B## + M3 = D###

Overview of Classes

1. NoteLetter

Represents the basic musical note letters (C, D, E, F, G, A, B). It supports operations like addition and subtraction to navigate the musical scale.

• Example Usage:

  from pymusictheory import NoteLetter
  
  note = NoteLetter.C + 4  # G
  print(note)  # Output: G
  

2. NoteAlteration

Represents alterations to a note (sharp, flat, natural). It defines how many semitones the alteration modifies the note by.

• Example Usage:

  from pymusictheory import NoteAlteration
  
  alteration = NoteAlteration.SHARP
  print(alteration.semitone_difference)  # Output: 1
  

3. Note

Represents a musical note without a specific octave. It combines a NoteLetter and a NoteAlteration to define a note like C#, Db, or F.

• Key Features:

  • Convert from string representation (e.g., "C#").
  • Calculate semitone offsets from C.
  • Generate all possible notes for a given semitone offset.

• Example Usage:

  from pymusictheory import Note
  
  note = Note.from_str("C#")
  print(note.semitone_offset)  # Output: 1
  

4. NoteInOctave

Represents a musical note in a specific octave. It extends Note by adding an octave number and supports operations like calculating absolute semitone offsets and adding intervals.

• Key Features:

  • Convert from string representation (e.g., "C4").
  • Calculate absolute semitone offsets from C0.
  • Add intervals to notes.

• Example Usage:

  from pymusictheory import NoteInOctave
  
  note = NoteInOctave.from_str("C4")
  print(note.absolute_semitone_offset)  # Output: 48
  

5. Interval

Represents musical intervals (e.g., major third, perfect fifth). It defines the semitone and letter distances for each interval.

• Example Usage:

  from pymusictheory import Interval
  
  interval = Interval.MAJOR_THIRD
  print(interval.semitone_distance)  # Output: 4
  

6. Chord

Represents a set of NoteInOctave objects, forming a chord. It allows iteration over the notes in the chord.

• Example Usage:

  from pymusictheory import NoteInOctave, Chord
  
  chord = Chord({NoteInOctave.from_str("C4"), NoteInOctave.from_str("E4"), NoteInOctave.from_str("G4")})
  for note in chord:
      print(note)
  

Relationships Between Classes

• NoteLetter and NoteAlteration combine to form a Note.
• Note and an octave number combine to form a NoteInOctave.
• Interval can be added to a NoteInOctave to calculate a new note.
• A Chord is a collection of NoteInOctave objects.

Common Use Cases

1. Calculate Semitone Offsets

from pymusictheory import Note

note = Note.from_str("F#")
print(note.semitone_offset)  # Output: 6

2. Add Intervals to Notes

from pymusictheory import NoteInOctave, Interval

note = NoteInOctave.from_str("C4")
new_note = note + Interval.PERFECT_FIFTH
print(new_note)  # Output: G4

note = NoteInOctave.from_str("B#3")
new_note = note + Interval.MAJOR_THIRD
print(new_note)  # Output: D##4

3. Generate Chords

from pymusictheory import NoteInOctave, Chord

chord = Chord({NoteInOctave.from_str("C4"), NoteInOctave.from_str("E4"), NoteInOctave.from_str("G4")})
print(chord)  # Output: {C4, E4, G4}

Installation

Ensure you have Python 3.13 or higher installed. Install the library using:

pip install pymusictheory

Contributing

Contributions are welcome! Please submit issues or pull requests on the GitHub repository.

License

This project is licensed under the MIT License.