This module defines objects for representing key signatures as well as key areas. The KeySignature is used in Measure objects for defining notated key signatures.
Given a pitch or music21.pitch.Pitch object, return the number of sharps found in that mode. The mode parameter can be ‘major’, ‘minor’, or most of the common church/jazz modes (‘dorian’, ‘mixolydian’, etc.) but not Locrian yet. If mode is omitted, the default mode is major. (extra points to anyone who can find the earliest reference to the Locrian mode in print. David Cohen and I (MSC) have been looking for this for years).
>>> from music21 import *
>>> key.pitchToSharps('c')
0
>>> key.pitchToSharps('c', 'minor')
-3
>>> key.pitchToSharps('a', 'minor')
0
>>> key.pitchToSharps('d')
2
>>> key.pitchToSharps('e-')
-3
>>> key.pitchToSharps('a')
3
>>> key.pitchToSharps('e', 'minor')
1
>>> key.pitchToSharps('f#', 'major')
6
>>> key.pitchToSharps('g-', 'major')
-6
>>> key.pitchToSharps('c#')
7
>>> key.pitchToSharps('g#')
8
>>> key.pitchToSharps('e', 'dorian')
2
>>> key.pitchToSharps('d', 'dorian')
0
>>> key.pitchToSharps('g', 'mixolydian')
0
>>> key.pitchToSharps('e-', 'lydian')
-2
>>> key.pitchToSharps('e-', 'lydian')
-2
>>> key.pitchToSharps('a', 'phrygian')
-1
>>> key.pitchToSharps('e', 'phrygian')
0
Given a number a positive/negative number of sharps, return a Pitch object set to the appropriate major key value.
>>> from music21 import *
>>> key.sharpsToPitch(1)
G
>>> key.sharpsToPitch(1)
G
>>> key.sharpsToPitch(2)
D
>>> key.sharpsToPitch(-2)
B-
>>> key.sharpsToPitch(-6)
G-
Note that these are :class:`music21.pitch.Pitch` objects not just names:
>>> k1 = key.sharpsToPitch(6)
>>> k1
F#
>>> k1.step
'F'
>>> k1.accidental
<accidental sharp>
Inherits from: Music21Object, JSONSerializer
>>> from music21 import *
>>> a = key.KeySignature(3)
>>> a
<music21.key.KeySignature of 3 sharps>
KeySignature attributes
- classSortOrder¶
Property which returns an number (int or otherwise) depending on the class of the Music21Object that represents a priority for an object based on its class alone – used as a tie for stream sorting in case two objects have the same offset and priority. Lower numbers are sorted to the left of higher numbers. For instance, Clef, KeySignature, TimeSignature all come (in that order) before Note. All undefined classes have classSortOrder of 20 – same as note.Note
>>> from music21 import * >>> tc = clef.TrebleClef() >>> tc.classSortOrder 0 >>> ks = key.KeySignature(3) >>> ks.classSortOrder 1New classes can define their own default classSortOrder
>>> class ExampleClass(base.Music21Object): ... classSortOrderDefault = 5 ... >>> ec1 = ExampleClass() >>> ec1.classSortOrder 5Attributes inherited from Music21Object: id, groups
KeySignature properties
- alteredPitches¶
Return a list of music21.pitch.Pitch objects that are altered by this KeySignature. That is, all Pitch objects that will receive an accidental.
>>> from music21 import * >>> a = key.KeySignature(3) >>> a.alteredPitches [F#, C#, G#] >>> b = key.KeySignature(1) >>> b.alteredPitches [F#] >>> c = key.KeySignature(9) >>> c.alteredPitches [F#, C#, G#, D#, A#, E#, B#, F##, C##] >>> d = key.KeySignature(-3) >>> d.alteredPitches [B-, E-, A-] >>> e = key.KeySignature(-1) >>> e.alteredPitches [B-] >>> f = key.KeySignature(-6) >>> f.alteredPitches [B-, E-, A-, D-, G-, C-] >>> g = key.KeySignature(-8) >>> g.alteredPitches [B-, E-, A-, D-, G-, C-, F-, B--]
- lily¶
returns the Lilypond representation of a KeySignature object
>>> from music21 import * >>> d = key.KeySignature(-1) >>> d.mode = 'minor' >>> print d.lily \key d \minor Major is assumed: >>> fsharp = key.KeySignature(6) >>> print fsharp.lily \key fis \major
- mode¶
- Get or set the mode.
- mx¶
Returns a musicxml.KeySignature object
>>> a = KeySignature(3) >>> a.sharps = -3 >>> mxKey = a.mx >>> mxKey.get('fifths') -3
- pitchAndMode¶
Returns a a two value list containing a music21.pitch.Pitch object that names this key and the value of mode.
>>> from music21 import * >>> key.KeySignature(-7).pitchAndMode (C-, None) >>> key.KeySignature(-6).pitchAndMode (G-, None) >>> key.KeySignature(-3).pitchAndMode (E-, None) >>> key.KeySignature(0).pitchAndMode (C, None) >>> key.KeySignature(1).pitchAndMode (G, None) >>> csharp = key.KeySignature(4) >>> csharp.mode = "minor" >>> csharp.pitchAndMode (C#, 'minor') >>> csharpPitch = csharp.pitchAndMode[0] >>> csharpPitch.accidental <accidental sharp>
- sharps¶
- Get or set the number of sharps.
Properties inherited from Music21Object: activeSite, beat, beatDuration, beatStr, beatStrength, classes, duration, measureNumberLocal, offset, priority
Properties inherited from JSONSerializer: json
KeySignature methods
- accidentalByStep(step)¶
given a step (C, D, E, F, etc.) return the accidental for that note in this key (using the natural minor for minor) or None if there is none.
>>> from music21 import * >>> g = key.KeySignature(1) >>> g.accidentalByStep("F") <accidental sharp> >>> g.accidentalByStep("G") >>> f = KeySignature(-1) >>> bbNote = note.Note("B-5") >>> f.accidentalByStep(bbNote.step) <accidental flat>Fix a wrong note in F-major:
>>> wrongBNote = note.Note("B#4") >>> if f.accidentalByStep(wrongBNote.step) != wrongBNote.accidental: ... wrongBNote.accidental = f.accidentalByStep(wrongBNote.step) >>> wrongBNote <music21.note.Note B->Set all notes to the correct notes for a key using the note’s Context:
>>> from music21 import * >>> s1 = stream.Stream() >>> s1.append(key.KeySignature(4)) # E-major or C-sharp-minor >>> s1.append(note.HalfNote("C")) >>> s1.append(note.HalfNote("E-")) >>> s1.append(key.KeySignature(-4)) # A-flat-major or F-minor >>> s1.append(note.WholeNote("A")) >>> s1.append(note.WholeNote("F#")) >>> for n in s1.notes: ... n.accidental = n.getContextByClass(key.KeySignature).accidentalByStep(n.step) >>> s1.show()![]()
- getScale()¶
Return a scale that is representative of this key.
>>> from music21 import * >>> ks = key.KeySignature(3) >>> ks <music21.key.KeySignature of 3 sharps> >>> ks.getScale() <music21.scale.MajorScale A major>
- transpose(value, inPlace=False)¶
Transpose the KeySignature by the user-provided value. If the value is an integer, the transposition is treated in half steps. If the value is a string, any Interval string specification can be provided. Alternatively, a music21.interval.Interval object can be supplied.
>>> a = KeySignature(2) >>> a.pitchAndMode (D, None) >>> b = a.transpose('p5') >>> b.pitchAndMode (A, None) >>> b.sharps 3 >>> c = b.transpose('-m2') >>> c.pitchAndMode (G#, None) >>> c.sharps 8 >>> d = c.transpose('-a3') >>> d.pitchAndMode (E-, None) >>> d.sharps -3Methods inherited from Music21Object: searchParentByAttr(), getContextAttr(), setContextAttr(), addContext(), addLocation(), addLocationAndActiveSite(), freezeIds(), getAllContextsByClass(), getContextByClass(), getOffsetBySite(), getSiteIds(), getSites(), getSpannerSites(), hasContext(), mergeAttributes(), purgeLocations(), removeLocationBySite(), removeLocationBySiteId(), setOffsetBySite(), show(), splitAtDurations(), splitAtQuarterLength(), splitByQuarterLengths(), unfreezeIds(), unwrapWeakref(), wrapWeakref(), write()
Methods inherited from JSONSerializer: jsonAttributes(), jsonComponentFactory(), jsonPrint(), jsonRead(), jsonWrite()
Inherits from: KeySignature, DiatonicScale, ConcreteScale, Scale, Music21Object, JSONSerializer
Note that a key is a sort of hypothetical/conceptual object. It probably has a scale (or scales) associated with it and a KeySignature, but not necessarily. EXPERIMENTAL
>>> from music21 import *
>>> cm = key.Key('c') # cminor.
>>> cm
<music21.key.Key of c minor>
>>> cm.sharps
-3
>>> cm.pitchFromDegree(3)
E-4
>>> cm.pitchFromDegree(7)
B-4
>>> Csharpmaj = key.Key('C#')
>>> Csharpmaj
<music21.key.Key of C# major>
Key attributes
Attributes without Documentation: tonic
Attributes inherited from KeySignature: classSortOrder
Attributes inherited from ConcreteScale: boundRange
Attributes inherited from Scale: type
Attributes inherited from Music21Object: id
Key properties
Properties inherited from KeySignature: alteredPitches, lily, mode, mx, pitchAndMode, sharps
Properties inherited from DiatonicScale: musicxml
Properties inherited from ConcreteScale: abstract, chord, isConcrete, name, pitches
Properties inherited from Music21Object: activeSite, beat, beatDuration, beatStr, beatStrength, classes, duration, measureNumberLocal, offset, priority
Properties inherited from JSONSerializer: json
Key methods
Methods inherited from KeySignature: accidentalByStep(), getScale(), transpose()
Methods inherited from DiatonicScale: getDominant(), getLeadingTone(), getParallelMajor(), getParallelMinor(), getRelativeMajor(), getRelativeMinor(), getTonic()
Methods inherited from ConcreteScale: derive(), deriveByDegree(), deriveRanked(), findMissing(), getChord(), getDegreeMaxUnique(), getPitches(), getScaleDegreeFromPitch(), isNext(), match(), next(), pitchFromDegree(), pitchesFromScaleDegrees(), romanNumeral()
Methods inherited from Music21Object: searchParentByAttr(), getContextAttr(), setContextAttr(), addContext(), addLocation(), addLocationAndActiveSite(), freezeIds(), getAllContextsByClass(), getContextByClass(), getOffsetBySite(), getSiteIds(), getSites(), getSpannerSites(), hasContext(), mergeAttributes(), purgeLocations(), removeLocationBySite(), removeLocationBySiteId(), setOffsetBySite(), show(), splitAtDurations(), splitAtQuarterLength(), splitByQuarterLengths(), unfreezeIds(), unwrapWeakref(), wrapWeakref(), write()
Methods inherited from JSONSerializer: jsonAttributes(), jsonComponentFactory(), jsonPrint(), jsonRead(), jsonWrite()