khodowany
57 lines
3.0 KiB
Python
57 lines
3.0 KiB
Python
"""Pure musical contracts; no reference files or filesystem access."""
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from __future__ import annotations
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import dataclasses
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import fractions
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import generator.solo.types as types
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F = fractions.Fraction
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def identifying_features(notes, source):
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"""Select a characteristic leap followed by return, wherever it occurs."""
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notes = tuple(notes)
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candidates = []
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for i in range(len(notes) - 2):
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a, b, c = notes[i:i + 3]
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leap, reply = b.pitch.number() - a.pitch.number(), c.pitch.number() - b.pitch.number()
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if 3 <= abs(leap) <= 9 and leap * reply < 0 and c.start - a.start <= 4:
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group = notes[i:min(len(notes), i + 4)]
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rhythm = tuple((n.start - a.start, n.end - n.start) for n in group)
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intervals = tuple(y.pitch.number() - x.pitch.number() for x, y in zip(group, group[1:]))
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candidates.append(types.IdentifyingFeature(a.event_id + '_identity', tuple(n.event_id for n in group), rhythm, intervals, source))
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return tuple(candidates[:1])
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def feature_error(feature, notes):
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by_id = {n.event_id: n for n in notes}
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actual = [by_id.get(identity) for identity in feature.events]
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if not actual or not all(actual):
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return 1.0
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first = actual[0].start
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rhythm = tuple((n.start - first, n.end - n.start) for n in actual)
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movement = tuple(b.pitch.number() - a.pitch.number() for a, b in zip(actual, actual[1:]))
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errors = []
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if 'rhythm' in feature.preserves:
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errors.append(1.0 if len(rhythm) != len(feature.rhythm) else sum(a != b for a,b in zip(rhythm,feature.rhythm))/max(1,len(rhythm)))
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if 'intervals' in feature.preserves or 'contour' in feature.preserves:
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if len(movement) != len(feature.intervals) or not movement and feature.intervals:
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errors.append(1.0)
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else:
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errors.append(sum(((a>0)-(a<0)) != ((b>0)-(b<0)) or 'intervals' in feature.preserves and abs(a-b)>2 for a,b in zip(movement,feature.intervals))/max(1,len(movement)))
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if 'exact_intervals' in feature.preserves:
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errors.append(float(movement != feature.intervals))
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if 'pitches' in feature.preserves:
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errors.append(float(tuple(n.pitch.number() for n in actual) != feature.pitches))
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return max(errors,default=0.0)
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def relationship(notes, reference):
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"""One joint relationship cost: timed movement, not absolute-pitch copying."""
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notes = tuple(notes)
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if len(notes) < 2 or len(reference.notes) < 2:
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return 0.0 if len(notes) == len(reference.notes) == 1 else 1.0
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actual = tuple(b.pitch.number() - a.pitch.number() for a, b in zip(notes, notes[1:]))
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expected = reference.contour()
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count = min(len(actual), len(expected))
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contour = sum(0.75 * (((a > 0) - (a < 0)) != ((b > 0) - (b < 0))) + 0.25 * min(1, max(0, abs(a - b) - 2) / 7) for a, b in zip(actual, expected)) / max(1, count)
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start, ref_start = notes[0].start, reference.notes[0].start
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rhythm = sum(min(1, float(abs((n.start - start) - (r.start - ref_start))) / 2) for n, r in zip(notes, reference.notes)) / min(len(notes), len(reference.notes))
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evidence = max(0, min(3, len(reference.notes)) - len(notes)) / 3
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return max(evidence, (contour + rhythm) / 2)
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