fix: dbsf zero div error (#872)

* fix: dbsf zero division error closes #871 * review suggestion Co-authored-by: Andrey Vasnetsov <[email protected]> --------- Co-authored-by: Andrey Vasnetsov <[email protected]>
qdrant · Jan 2, 2025 · 67b7eb8 · 67b7eb8
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diff --git a/qdrant_client/hybrid/fusion.py b/qdrant_client/hybrid/fusion.py
@@ -33,6 +33,9 @@ def distribution_based_score_fusion(
     responses: list[list[models.ScoredPoint]], limit: int
 ) -> list[models.ScoredPoint]:
     def normalize(response: list[models.ScoredPoint]) -> list[models.ScoredPoint]:
+        if len(response) <= 1:
+            return response
+
         total = sum([point.score for point in response])
         mean = total / len(response)
         variance = sum([(point.score - mean) ** 2 for point in response]) / (len(response) - 1)

diff --git a/qdrant_client/hybrid/test_reranking.py b/qdrant_client/hybrid/test_reranking.py
@@ -50,6 +50,9 @@ def test_distribution_based_score_fusion() -> None:
     assert fused[1].id == 0
     assert fused[2].id == 4
 
+    fused = distribution_based_score_fusion([[responses[0][0]]], limit=3)
+    assert fused[0].id == 1
+
 
 def test_reciprocal_rank_fusion_empty_responses() -> None:
     responses: list[list[models.ScoredPoint]] = [[]]