music21.analysis.transposition

TranspositionChecker

class music21.analysis.transposition.TranspositionChecker(pitches=None)

Given a list of pitches, checks for the number of distinct transpositions.

>>> pList = [pitch.Pitch('C4'), pitch.Pitch('E4'), pitch.Pitch('G#4')]
>>> tc = analysis.transposition.TranspositionChecker(pList)
>>> tc.numDistinctTranspositions()
4
>>> allNormalOrderPitchTuples = tc.getPitchesOfDistinctTranspositions()
>>> allNormalOrderPitchTuples
[(<music21.pitch.Pitch C>, <music21.pitch.Pitch E>,
                                     <music21.pitch.Pitch G#>),
 (<music21.pitch.Pitch C#>, <music21.pitch.Pitch F>,
                                     <music21.pitch.Pitch A>),
 (<music21.pitch.Pitch D>, <music21.pitch.Pitch F#>,
                                     <music21.pitch.Pitch A#>),
 (<music21.pitch.Pitch E->, <music21.pitch.Pitch G>,
                                     <music21.pitch.Pitch B>)]
>>> myChord = chord.Chord(['C', 'E-', 'F#', 'A'])
>>> pList = myChord.pitches
>>> tc = analysis.transposition.TranspositionChecker(pList)
>>> allNormalOrderChords = tc.getChordsOfDistinctTranspositions()
>>> allNormalOrderChords
[<music21.chord.Chord C E- F# A>,
 <music21.chord.Chord C# E G A#>,
 <music21.chord.Chord D F G# B>]

TranspositionChecker methods

TranspositionChecker.getChordsOfDistinctTranspositions()

Outputs chords for each distinct transposition (normal order).

>>> pList = [pitch.Pitch('C4'), pitch.Pitch('E4'), pitch.Pitch('G#4')]
>>> tc = analysis.transposition.TranspositionChecker(pList)
>>> tc.getChordsOfDistinctTranspositions()
[<music21.chord.Chord C E G#>,
 <music21.chord.Chord C# F A>,
 <music21.chord.Chord D F# A#>,
 <music21.chord.Chord E- G B>]
TranspositionChecker.getPitchesOfDistinctTranspositions()

Outputs pitch tuples for each distinct transposition (normal order).

>>> pList = [pitch.Pitch('C4'), pitch.Pitch('E4'), pitch.Pitch('G#4')]
>>> tc = analysis.transposition.TranspositionChecker(pList)
>>> tc.getPitchesOfDistinctTranspositions()
[(<music21.pitch.Pitch C>, <music21.pitch.Pitch E>, <music21.pitch.Pitch G#>),
 (<music21.pitch.Pitch C#>, <music21.pitch.Pitch F>, <music21.pitch.Pitch A>),
 (<music21.pitch.Pitch D>, <music21.pitch.Pitch F#>, <music21.pitch.Pitch A#>),
 (<music21.pitch.Pitch E->, <music21.pitch.Pitch G>, <music21.pitch.Pitch B>)]
TranspositionChecker.getTranspositions()

Gets all 12 transpositions (distinct or otherwise)

>>> p = [pitch.Pitch('D#')]
>>> tc = analysis.transposition.TranspositionChecker(p)
>>> tc.getTranspositions()
[[<music21.pitch.Pitch E->],
[<music21.pitch.Pitch E>],
[<music21.pitch.Pitch F>],
[<music21.pitch.Pitch F#>],
[<music21.pitch.Pitch G>],
[<music21.pitch.Pitch G#>],
[<music21.pitch.Pitch A>],
[<music21.pitch.Pitch B->],
[<music21.pitch.Pitch B>],
[<music21.pitch.Pitch C>],
[<music21.pitch.Pitch C#>],
[<music21.pitch.Pitch D>]]
TranspositionChecker.listDistinctNormalOrders()

List the distinct normal orders (without duplication).

>>> pList = [pitch.Pitch('C4'), pitch.Pitch('E4'), pitch.Pitch('G#4')]
>>> tc = analysis.transposition.TranspositionChecker(pList)
>>> tc.listDistinctNormalOrders()
[[0, 4, 8], [1, 5, 9], [2, 6, 10], [3, 7, 11]]
TranspositionChecker.listNormalOrders()

List the normal orders for all 12 transpositions

>>> pList = [pitch.Pitch('C4'), pitch.Pitch('E4'), pitch.Pitch('G#4')]
>>> tc = analysis.transposition.TranspositionChecker(pList)
>>> tc.listNormalOrders()
[[0, 4, 8], [1, 5, 9], [2, 6, 10], [3, 7, 11],
 [0, 4, 8], [1, 5, 9], [2, 6, 10], [3, 7, 11],
 [0, 4, 8], [1, 5, 9], [2, 6, 10], [3, 7, 11]]
TranspositionChecker.numDistinctTranspositions()

Gives the number of distinct transpositions (normal orders).

>>> pList = [pitch.Pitch('C4'), pitch.Pitch('E4'), pitch.Pitch('G#4')]
>>> tc = analysis.transposition.TranspositionChecker(pList)
>>> tc.numDistinctTranspositions()
4