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59 lines
1.7 KiB
Python
59 lines
1.7 KiB
Python
"""Explore a key — its chords, progressions, and relationships."""
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from pytheory import Key
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def explore_key(tonic, mode="major"):
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key = Key(tonic, mode)
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sig = key.signature
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acc = ", ".join(sig["accidentals"]) or "none"
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print(f"{'=' * 60}")
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print(f" {key}")
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print(f"{'=' * 60}")
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print()
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print(f" Scale: {' '.join(key.note_names)}")
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print(f" Signature: {sig['sharps']} sharps, {sig['flats']} flats ({acc})")
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print(f" Relative: {key.relative}")
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print(f" Parallel: {key.parallel}")
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print()
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# Diatonic triads
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print(" Diatonic Triads:")
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for chord in key.scale.harmonize():
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numeral = chord.analyze(tonic, mode) or "?"
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print(f" {numeral:6s} {chord.identify()}")
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print()
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# Seventh chords
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print(" Seventh Chords:")
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for name in key.seventh_chords:
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print(f" {name}")
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print()
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# Common progressions
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print(" Common Progressions:")
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progressions = {
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"Pop": ("I", "V", "vi", "IV"),
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"Blues": ("I", "IV", "V"),
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"50s": ("I", "vi", "IV", "V"),
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"Jazz": ("ii", "V", "I"),
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}
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for label, numerals in progressions.items():
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chords = key.progression(*numerals)
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names = [c.identify() for c in chords]
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print(f" {label:8s} {' → '.join(numerals):20s} {' → '.join(names)}")
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print()
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# Borrowed chords
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borrowed = key.borrowed_chords
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if borrowed:
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print(f" Borrowed from {key.parallel}:")
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for name in borrowed[:4]:
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print(f" {name}")
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print()
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# Explore several keys
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for tonic, mode in [("C", "major"), ("G", "major"), ("A", "minor"), ("E", "major")]:
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explore_key(tonic, mode)
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