Implemented sort order matches by common letter count largest to smallest #295
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maxbachmann
reviewed
Dec 17, 2020
| sorted(sl, key=lambda i: i[1], reverse=True) | ||
| else: | ||
| best_list = sorted(sl, key=lambda i: i[1], reverse=True) | ||
| return sortByCommonLetter(sl, query)[0: min(limit, len(sl))] if limit is not None else \ |
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from a performance standpoint this is a bad idea. When the user is only interested in 5 elements (the default), but has e.g. 1 million choices, this will sort 1 million choices (with a slow algorithm, since it counts all the letters) and then only takes the best 5 elements.
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| def sortByCommonLetter(sl, query): | ||
| """This function further sorts the strings with the same scores by common letter count to the query.""" | ||
| current_score, last_index = -1, -1 | ||
| # Iterate over list and look for words with the same scores | ||
| for i in range(0, len(sl)): | ||
| # Identify the indexes of the strings with the same scores | ||
| if sl[i][1] != current_score or i == len(sl) - 1: | ||
| current_score = sl[i][1] | ||
| # First iteration, there are no previous words so we do not have to do anything | ||
| if last_index == -1: | ||
| last_index = i | ||
| continue | ||
| # Found a group of words with the same scores! Now sort them | ||
| if i - last_index > 1: | ||
| count_list = [] | ||
| for j in range(last_index, i): | ||
| count_list.append((sl[j][0], calculateCommonLetter(query, sl[j][0]))) | ||
| count_list = sorted(count_list, key=lambda k: k[1], reverse=True) | ||
| # Copy the sorted portion | ||
| for j in range(0, len(count_list)): | ||
| sl[last_index + j] = (count_list[j][0], current_score) | ||
| last_index = i | ||
| return sl |
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This algorithm is broken for quite a few cases. A couple quick examples:
- When a processor is used the results might not be correct:
query_1 = 'COMPANY'
choices_1 = ['Company 1', 'company', 'company', 'Company 2', 'Awesome Company']
process.extractOne(query_1, choices_1, scorer=fuzz.partial_token_set_ratio, char_sort=True)
-> ('Company 1', 100)
- it matters wether a element is query or choice
query_1 = 'Company'
choices_1 = ['Company 1', 'Company', 'Company 2', 'Awesome Company']
process.extractOne(query_1, choices_1, scorer=fuzz.partial_token_set_ratio, char_sort=True)
-> ('Company 1', 100)
|
Overall I am personally not really convinced, this should be added at all for two reasons
|
Added penalty for character mismatches in sortByCommonLetter Added call to full_process in sortByCommonLetter Fixed incorrect variable names (weird!)
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This pull request addresses the problem in this issue: #280
All the code changes + unit tests are in process.py and test_fuzzywuzzy.py.
All the old and new test cases in test_fuzzywuzzy.py are passed.