diff --git a/qurator/dinglehopper/flexible_character_accuracy.py b/qurator/dinglehopper/flexible_character_accuracy.py
index 241ef4a..4ace63c 100644
--- a/qurator/dinglehopper/flexible_character_accuracy.py
+++ b/qurator/dinglehopper/flexible_character_accuracy.py
@@ -13,12 +13,12 @@ Note that we deviated from the original algorithm at some places.
import sys
from collections import Counter
-from functools import lru_cache, reduce
+from functools import lru_cache, reduce, partial
from itertools import product, takewhile
-from typing import List, Tuple, Optional
+from multiprocessing import cpu_count, get_context
+from typing import List, Tuple, Optional, Union
from Levenshtein import editops
-from multimethod import multimethod
from . import ExtractedText
@@ -38,57 +38,57 @@ else:
)
-@multimethod
def flexible_character_accuracy(
- gt: ExtractedText, ocr: ExtractedText
+ gt: Union[str, ExtractedText],
+ ocr: Union[str, ExtractedText],
+ n_cpu: int = cpu_count(),
) -> Tuple[float, List[Match]]:
"""Calculate the flexible character accuracy.
Reference: contains steps 1-7 of the flexible character accuracy algorithm.
- :param gt: The ground truth ExtractedText object.
- :param ocr: The ExtractedText object to compare the ground truth with.
- :return: Score between 0 and 1 and match objects.
- """
- return flexible_character_accuracy(gt.text, ocr.text)
-
-
-@multimethod
-def flexible_character_accuracy(gt: str, ocr: str) -> Tuple[float, List[Match]]:
- """Calculate the flexible character accuracy.
-
- Reference: contains steps 1-7 of the flexible character accuracy algorithm.
-
:param gt: The ground truth text.
:param ocr: The text to compare the ground truth with.
+ :param n_cpu: numbers of cpus to use for multiprocessing.
:return: Score between 0 and 1 and match objects.
"""
+ if isinstance(gt, ExtractedText):
+ gt = gt.text
+ if isinstance(ocr, ExtractedText):
+ ocr = ocr.text
+
best_score = -sys.maxsize
best_matches = []
# TODO: should this be configurable?
- combinations = product(
- range(15, 31, 5), range(0, 24, 3), range(0, 4, 1), range(0, 6, 1)
- )
- # TODO: place to parallelize the algorithm?
- for (edit_dist, length_diff, offset, length) in combinations:
- coef = Coefficients(
+ coeffs = (
+ Coefficients(
edit_dist=edit_dist, length_diff=length_diff, offset=offset, length=length
)
+ for edit_dist, length_diff, offset, length in product(
+ range(15, 31, 5), range(0, 24, 3), range(0, 4, 1), range(0, 6, 1)
+ )
+ )
+ with get_context("spawn").Pool(processes=n_cpu) as pool:
# Steps 1 - 6 of the flexible character accuracy algorithm.
- matches = match_with_coefficients(gt, ocr, coef)
- # Step 7 of the flexible character accuracy algorithm.
- score = character_accuracy_for_matches(matches)
- if score > best_score:
- best_score = score
- best_matches = matches
- # early breaking: we only need one perfect fit
- if best_score >= 1:
- break
+ # We only use multiprocessing if we have more than 2 cpus available.
+ # Otherwise the overhead for creating processes and filling caches is too big.
+ map_fun = partial(pool.imap_unordered, chunksize=10) if n_cpu > 2 else map
+ for matches in map_fun(
+ partial(match_with_coefficients, gt=gt, ocr=ocr), coeffs
+ ):
+ # Step 7 of the flexible character accuracy algorithm.
+ score = character_accuracy_for_matches(matches)
+ if score > best_score:
+ best_score = score
+ best_matches = matches
+ # early breaking: we only need one perfect fit
+ if best_score >= 1:
+ break
return best_score, best_matches
-def match_with_coefficients(gt: str, ocr: str, coef: Coefficients) -> List[Match]:
+def match_with_coefficients(coef: Coefficients, gt: str, ocr: str) -> List[Match]:
"""Match ground truth with ocr and consider a given set of coefficients.
Reference: contains steps 1 - 6 of the flexible character accuracy algorithm.
diff --git a/qurator/dinglehopper/tests/test_flexible_character_accuracy.py b/qurator/dinglehopper/tests/test_flexible_character_accuracy.py
index ad62798..6ef316b 100644
--- a/qurator/dinglehopper/tests/test_flexible_character_accuracy.py
+++ b/qurator/dinglehopper/tests/test_flexible_character_accuracy.py
@@ -104,7 +104,7 @@ def extended_case_to_text(gt, ocr):
@pytest.mark.parametrize(CASE_ARGS, [*SIMPLE_CASES, *COMPLEX_CASES])
def test_flexible_character_accuracy_str(gt, ocr, first_line_score, all_line_score):
- score, _ = flexible_character_accuracy(gt, ocr)
+ score, _ = flexible_character_accuracy(gt, ocr, 1)
assert score == pytest.approx(all_line_score)
@@ -132,7 +132,7 @@ def test_flexible_character_accuracy_xml(gt, ocr, first_line_score, all_line_sco
gt_text = get_extracted_text(gt)
ocr_text = get_extracted_text(ocr)
- score, _ = flexible_character_accuracy(gt_text, ocr_text)
+ score, _ = flexible_character_accuracy(gt_text, ocr_text, 1)
assert score == pytest.approx(all_line_score)
@@ -186,7 +186,7 @@ def test_flexible_character_accuracy(config, ocr):
)
expected_score = character_accuracy(expected_dist)
- result, matches = flexible_character_accuracy(gt, ocr)
+ result, matches = flexible_character_accuracy(gt, ocr, 1)
agg = reduce(
lambda acc, match: acc + Counter(match.dist._asdict()), matches, Counter()
)
@@ -201,7 +201,7 @@ def test_flexible_character_accuracy_extended(
):
"""Tests from figure 4 in the 10.1016/j.patrec.2020.02.003."""
gt_sentence, ocr_sentence = extended_case_to_text(gt, ocr)
- result, _ = flexible_character_accuracy(gt_sentence, ocr_sentence)
+ result, _ = flexible_character_accuracy(gt_sentence, ocr_sentence, 1)
assert result == pytest.approx(all_line_score, abs=0.001)
@@ -210,7 +210,7 @@ def test_match_with_coefficients(gt, ocr, first_line_score, all_line_score):
coef = Coefficients()
if not isinstance(gt, str):
gt, ocr = extended_case_to_text(gt, ocr)
- matches = match_with_coefficients(gt, ocr, coef)
+ matches = match_with_coefficients(coef, gt, ocr)
score = character_accuracy_for_matches(matches)
assert score == pytest.approx(all_line_score, abs=0.001)