49 lines
1.5 KiB
Python
49 lines
1.5 KiB
Python
# SPDX-FileCopyrightText: 2022 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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"""Utilities to measure OCR quality."""
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from __future__ import annotations
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import re
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from collections.abc import Iterable
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class OcrQualityDictionary:
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"""Manages a dictionary for simple OCR quality checks."""
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def __init__(self, *, wordlist: Iterable[str]):
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"""Construct a dictionary from a list of words.
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Words for which capitalization is important should be capitalized in the
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dictionary. Words that contain spaces or other punctuation will never match.
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"""
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self.dictionary = set(wordlist)
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def measure_words_matched(self, ocr_text: str) -> float:
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"""Check how many unique words in the OCR text match a dictionary.
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Words with mixed capitalized are only considered a match if the test word
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matches that capitalization.
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Returns:
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number of words that match / number
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"""
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text = re.sub(r"[0-9_]+", ' ', ocr_text)
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text = re.sub(r'\W+', ' ', text)
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text_words_list = re.split(r'\s+', text)
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text_words = {w for w in text_words_list if len(w) >= 3}
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matches = 0
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for w in text_words:
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if w in self.dictionary or (
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w != w.lower() and w.lower() in self.dictionary
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):
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matches += 1
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if matches > 0:
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hit_ratio = matches / len(text_words)
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else:
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hit_ratio = 0.0
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return hit_ratio
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