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librosa.key_to_notes

librosa.key_to_notes(key, *, unicode=True)[source]

Lists all 12 note names in the chromatic scale, as spelled according to a given key (major or minor).

This function exists to resolve enharmonic equivalences between different spellings for the same pitch (e.g. C♯ vs D♭), and is primarily useful when producing human-readable outputs (e.g. plotting) for pitch content.

Note names are decided by the following rules:

  1. If the tonic of the key has an accidental (sharp or flat), that accidental will be used consistently for all notes.

  2. If the tonic does not have an accidental, accidentals will be inferred to minimize the total number used for diatonic scale degrees.

  3. If there is a tie (e.g., in the case of C:maj vs A:min), sharps will be preferred.

Parameters:
keystring

Must be in the form TONIC:key. Tonic must be upper case (CDEFGAB), key must be lower-case (maj or min).

Single accidentals (b!♭ for flat, or #♯ for sharp) are supported.

Examples: C:maj, Db:min, A♭:min.

unicodebool

If True (default), use Unicode symbols (♯𝄪♭𝄫)for accidentals.

If False, Unicode symbols will be mapped to low-order ASCII representations:

♯ -> #, 𝄪 -> ##, ♭ -> b, 𝄫 -> bb
Returns:
noteslist

notes[k] is the name for semitone k (starting from C) under the given key. All chromatic notes (0 through 11) are included.

See also

midi_to_note

Examples

C:maj will use all sharps

>>> librosa.key_to_notes('C:maj')
['C', 'C♯', 'D', 'D♯', 'E', 'F', 'F♯', 'G', 'G♯', 'A', 'A♯', 'B']

A:min has the same notes

>>> librosa.key_to_notes('A:min')
['C', 'C♯', 'D', 'D♯', 'E', 'F', 'F♯', 'G', 'G♯', 'A', 'A♯', 'B']

A♯:min will use sharps, but spell note 0 (C) as B♯

>>> librosa.key_to_notes('A#:min')
['B♯', 'C♯', 'D', 'D♯', 'E', 'E♯', 'F♯', 'G', 'G♯', 'A', 'A♯', 'B']

G♯:maj will use a double-sharp to spell note 7 (G) as F𝄪:

>>> librosa.key_to_notes('G#:maj')
['B♯', 'C♯', 'D', 'D♯', 'E', 'E♯', 'F♯', 'F𝄪', 'G♯', 'A', 'A♯', 'B']

F♭:min will use double-flats

>>> librosa.key_to_notes('Fb:min')
['D𝄫', 'D♭', 'E𝄫', 'E♭', 'F♭', 'F', 'G♭', 'A𝄫', 'A♭', 'B𝄫', 'B♭', 'C♭']