chord-progression-network 0.1.7

Network transition chord progressions

Chord Progression Network

Network transition chord progression generator

DESCRIPTION

This class generates network transition chord progressions. The transitions are given by a net of scale positions, and the chord "flavors" are defined by a chord_map of types. The chords that are returned are either named chords or lists of three or more named notes with octaves.

The chord types are as follows:

'' (i.e. an empty string) means a major chord.
'm' signifies a minor chord.
'7' is a seventh chord and 'M7' is a major 7th chord.
'dim' is a diminished chord and 'aug' is augmented.
'9', '11', and '13' are extended 7th chords.
'M9', 'M11', and 'M13' are extended major-7th chords.
'm9', 'm11', and 'm13' are extended minor-7th chords.

For the major scale (ionian mode), this chord_map is ['', 'm', 'm', '', '', 'm', 'dim']. The dorian mode is ['m', 'm', '', '', 'm', 'dim', '']. A chromatic scale is all minors. This can be set in the constructor, or seen by printing it after Generator construction.

The tonic attribute means that if the first chord of the progression is being generated, then for 0 choose a random successor of the first chord, as defined by the net attribute. For 1, return the first chord in the scale. For any other value, choose a random value of the entire scale.

The resolve attribute means that if the last progression chord is being generated, then for 0 choose a random successor. As for the tonic, for 1, return the first chord in the scale, and for any other value, choose a random value of the entire scale. In all other cases (i.e. the middle chords of the progression), choose a random successor.

By default, all chords and notes with accidentals are returned as sharps. If you want flats, set the flat attribute to True in the constructor.

If the substitute attribute is set to True, then the progression chords are subject to extended, "jazz" chord, including tritone substitution. For now, for this work-in-progress advanced option, please see the substitution() method in the source...

SYNOPSIS

from chord_progression_network import Generator

g = Generator( # defaults
    max=8,
    scale_note='C',
    scale_name='major',
    octave=4,
    net={
        1: [1, 2, 3, 4, 5, 6],
        2: [3, 4, 5],
        3: [1, 2, 4, 6],
        4: [1, 3, 5, 6],
        5: [1, 4, 6],
        6: [1, 2, 4, 5],
        7: [],
    },
    chord_map=[ '', 'm', 'm', '', '', 'm', 'dim' ],
    tonic=1,
    resolve=1,
    flat=False,
    chord_phrase=False,
    substitute=False,
    verbose=False,
)
phrase = g.generate()

MUSICAL EXAMPLES

from music21 import chord, stream
from chord_progression_network import Generator

g = Generator(verbose=True)
phrase = g.generate()

s = stream.Score()
p = stream.Part()

for notes in phrase:
    p.append(chord.Chord(notes, type='whole'))

s.append(p)

s.show()

from music21 import chord, duration, stream
from chord_progression_network import Generator
from random_rhythms import Rhythm

r = Rhythm(
    durations=[ 1/2, 1/3, 1, 3/2, 2 ],
    groups={1/3: 3, 1/2: 2},
)
motifs = [ r.motif() for _ in range(4) ]

s = stream.Score()
p = stream.Part()

g = Generator()

for m in motifs:
    g.max = len(m)
    phrase = g.generate()
    for i, d in enumerate(m):
        c = chord.Chord(phrase[i])
        c.duration = duration.Duration(d)
        p.append(c)
s.append(p)

s.show()