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45 lines
1.1 KiB
Python
45 lines
1.1 KiB
Python
from __future__ import division
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import unicodedata
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from typing import Tuple
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from multimethod import multimethod
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from uniseg.graphemecluster import grapheme_clusters
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from qurator.dinglehopper.edit_distance import distance
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from qurator.dinglehopper.ocr_files import ExtractedText
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@multimethod
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def character_error_rate_n(reference: str, compared: str) -> Tuple[float, int]:
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"""
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Compute character error rate.
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:return: character error rate and length of the reference
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"""
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d = distance(reference, compared)
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n = len(list(grapheme_clusters(unicodedata.normalize('NFC', reference))))
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if d == 0:
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return 0, n
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if n == 0:
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return float('inf'), n
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return d/n, n
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# XXX Should we really count newlines here?
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@multimethod
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def character_error_rate_n(reference: ExtractedText, compared: ExtractedText) -> Tuple[float, int]:
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return character_error_rate_n(reference.text, compared.text)
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def character_error_rate(reference, compared) -> float:
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"""
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Compute character error rate.
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:return: character error rate
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"""
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cer, _ = character_error_rate_n(reference, compared)
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return cer
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