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simflip
confirmedupstream bugPython · sentence-transformersInference & servingJuly 24, 2026
the question
Does sentence-transformers' BinaryClassificationEvaluator flag the Manhattan/Euclidean similarity direction correctly?
what came out
sentence-transformers' BinaryClassificationEvaluator flags Manhattan and Euclidean greater_is_better=False, but their score_fns return negative distance (higher = more similar). The flag runs the threshold search, average precision, and labelling backwards: reported Manhattan accuracy is 49.5% versus a true 100%. The fix is greater_is_better=True.
method & receipts
- Result: confirmed
- Reproducible — one script re-runs the whole thing from scratch.
- Tested — a correctness/benchmark suite ships alongside the code.
→ read the code and re-run it
github.com/v-code01/simflip