51 lines
2.1 KiB
Python
51 lines
2.1 KiB
Python
"""Confidence bands: the single source of truth for the cut points.
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Copy this file into the backend. Everything that needs a band (the review queue,
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an exported sheet, the approve gate) imports from here, so they never disagree
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about what counts as red.
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GREEN >= 0.95 clean print, straight through
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AMBER 0.90-0.95 slightly unclear, check it
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RED < 0.90 handwriting or a messy scan
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BLANK a mandatory field with no value
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UNSCORED no word scores came back for the value
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The approve gate: every field that isn't green must be verified by a person before the
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run can be approved (needs_review). Amber is not sampled; it is checked like red.
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Calibration (from the prototype these rules came from): crisp print scored 0.90 and
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up, handwriting clustered in 0.80-0.89, and 0.70-0.79 was empty. 0.90 sits in that
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gap. 0.95 splits off the slightly unclear 0.90-0.95 reads from clean print.
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What a band claims: the score is the model's own legibility rating. Green means the
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text was read cleanly, NOT that the value is correct; a confident misread scores
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green. Red is the useful direction: it reliably surfaces handwriting.
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"""
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from __future__ import annotations
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from typing import Iterable, Optional
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GREEN_THRESHOLD = 0.95
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CONFIDENCE_THRESHOLD = 0.90
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BANDS = ("green", "amber", "red", "blank", "unscored")
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def band_of(score: float) -> str:
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if score >= GREEN_THRESHOLD:
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return "green"
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return "amber" if score >= CONFIDENCE_THRESHOLD else "red"
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def field_band(word_scores: Optional[Iterable[float]], value: Optional[str], mandatory: bool = False) -> str:
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"""A field's band. It takes its WORST word score, so one shaky word can't hide in
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a clean-looking field. A blank mandatory field is flagged whatever its score."""
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if mandatory and not (value or "").strip():
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return "blank"
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scores = list(word_scores or [])
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return band_of(min(scores)) if scores else "unscored"
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def needs_review(band: str) -> bool:
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"""Every band but green must be verified by a person before the run can be approved."""
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return band != "green"
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