mirror of
https://github.com/kennethreitz/pytheory.git
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kennethreitz
9da3ac8b28
- circle_of_fifths.py — visualize keys around the circle - chord_identifier.py — identify chords from notes and fingerings - key_explorer.py — explore keys, signatures, progressions, borrowed chords - temperament_comparison.py — compare equal, Pythagorean, and meantone - chord_tension.py — analyze tension, consonance, and voice leading - world_scales.py — scales from 6 musical traditions - fretboard_explorer.py — instruments, tunings, capo transposition - midi_converter.py — MIDI ↔ note ↔ frequency reference - progression_writer.py — famous progressions, Nashville numbers, random generation - interval_trainer.py — interval names, songs, and consonance ranking - overtone_series.py — harmonics and why chords sound good - key_detection.py — detect keys from melodies and chord progressions Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
82 lines
2.6 KiB
Python
82 lines
2.6 KiB
Python
"""Build and analyze chord progressions in any key."""
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from pytheory import Key, Chord
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def show_progression(key, numerals, label=""):
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chords = key.progression(*numerals)
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if label:
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print(f" {label}")
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print(f" Key: {key}")
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print(f" Progression: {' – '.join(numerals)}")
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print()
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for numeral, chord in zip(numerals, chords):
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t = chord.tension
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print(
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f" {numeral:6s} {chord.identify():20s} "
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f"tension={t['score']:.2f} "
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f"{'*** DOMINANT ***' if t['has_dominant_function'] else ''}"
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)
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print()
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# ── Famous Progressions ─────────────────────────────────────────────────
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print("Famous Chord Progressions")
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print("=" * 65)
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print()
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key_c = Key("C", "major")
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show_progression(key_c, ("I", "V", "vi", "IV"),
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"The Pop Progression (Let It Be, No Woman No Cry, Someone Like You)")
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show_progression(key_c, ("I", "vi", "IV", "V"),
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"The 50s Progression (Stand By Me, Every Breath You Take)")
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show_progression(key_c, ("ii", "V", "I"),
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"Jazz ii–V–I (the backbone of jazz harmony)")
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show_progression(key_c, ("I", "IV", "V", "I"),
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"The Three-Chord Trick (blues, rock, country)")
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# ── Same Progression in Different Keys ──────────────────────────────────
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print("─" * 65)
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print()
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print("I – V – vi – IV in every key:")
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print()
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for tonic in ["C", "G", "D", "A", "E", "F", "Bb", "Eb"]:
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key = Key(tonic, "major")
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chords = key.progression("I", "V", "vi", "IV")
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names = [c.identify() for c in chords]
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print(f" {tonic} major: {' → '.join(names)}")
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# ── Nashville Number System ─────────────────────────────────────────────
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print()
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print("─" * 65)
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print()
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print("Nashville Number System:")
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print(" (Same thing as Roman numerals, but with integers)")
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print()
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key_g = Key("G", "major")
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chords = key_g.nashville(1, 5, 6, 4)
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names = [c.identify() for c in chords]
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print(f" G major: 1 – 5 – 6 – 4 → {' → '.join(names)}")
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# ── Random Progression Generator ────────────────────────────────────────
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print()
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print("─" * 65)
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print()
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print("Random 8-bar progressions:")
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print()
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for _ in range(3):
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key = Key("C", "major")
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chords = key.random_progression(8)
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names = [c.identify().split()[0] for c in chords] # Just root names
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print(f" | {' | '.join(names)} |")
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