Fixed ZeroDivisionError in JoinDocuments

haystack/components/joiners/document_joiner.py

@@ -196,8 +196,12 @@ def _distribution_based_rank_fusion(self, document_lists: List[List[Document]])
             min_score = mean_score - 3 * std_dev
             max_score = mean_score + 3 * std_dev
 
-            for doc in documents:
-                doc.score = (doc.score - min_score) / (max_score - min_score)
+            if max_score == min_score:
+                for doc in documents:
+                    doc.score = 0
+            else:
+                for doc in documents:
+                    doc.score = (doc.score - min_score) / (max_score - min_score)
 
         output = self._concatenate(document_lists=document_lists)
 

releasenotes/notes/release-note-9b2bc03a8a398078.yaml

@@ -0,0 +1,65 @@
+---
+prelude: >
+    Replace this text with content to appear at the top of the section for this
+    release. All of the prelude content is merged together and then rendered
+    separately from the items listed in other parts of the file, so the text
+    needs to be worded so that both the prelude and the other items make sense
+    when read independently. This may mean repeating some details. Not every
+    release note requires a prelude. Usually only notes describing major
+    features or adding release theme details should have a prelude.
+features:
+  - |
+    List new features here, or remove this section.  All of the list items in
+    this section are combined when the release notes are rendered, so the text
+    needs to be worded so that it does not depend on any information only
+    available in another section, such as the prelude. This may mean repeating
+    some details.
+issues:
+  - |
+    List known issues here, or remove this section.  All of the list items in
+    this section are combined when the release notes are rendered, so the text
+    needs to be worded so that it does not depend on any information only
+    available in another section, such as the prelude. This may mean repeating
+    some details.
+upgrade:
+  - |
+    List upgrade notes here, or remove this section.  All of the list items in
+    this section are combined when the release notes are rendered, so the text
+    needs to be worded so that it does not depend on any information only
+    available in another section, such as the prelude. This may mean repeating
+    some details.
+deprecations:
+  - |
+    List deprecations notes here, or remove this section.  All of the list
+    items in this section are combined when the release notes are rendered, so
+    the text needs to be worded so that it does not depend on any information
+    only available in another section, such as the prelude. This may mean
+    repeating some details.
+critical:
+  - |
+    Add critical notes here, or remove this section.  All of the list items in
+    this section are combined when the release notes are rendered, so the text
+    needs to be worded so that it does not depend on any information only
+    available in another section, such as the prelude. This may mean repeating
+    some details.
+security:
+  - |
+    Add security notes here, or remove this section.  All of the list items in
+    this section are combined when the release notes are rendered, so the text
+    needs to be worded so that it does not depend on any information only
+    available in another section, such as the prelude. This may mean repeating
+    some details.
+fixes:
+  - |
+    Add normal bug fixes here, or remove this section.  All of the list items
+    in this section are combined when the release notes are rendered, so the
+    text needs to be worded so that it does not depend on any information only
+    available in another section, such as the prelude. This may mean repeating
+    some details.
+other:
+  - |
+    Add other notes here, or remove this section.  All of the list items in
+    this section are combined when the release notes are rendered, so the text
+    needs to be worded so that it does not depend on any information only
+    available in another section, such as the prelude. This may mean repeating
+    some details.

test/components/joiners/test_document_joiner.py

@@ -145,6 +145,36 @@ def test_run_with_distribution_based_rank_fusion_join_mode(self):
         ]
         assert all(doc.id in expected_document_ids for doc in output["documents"])
 
+    def test_run_with_zeroexceptionerror_distribution_based_rank_fusion_join_mode(self):
+        joiner = DocumentJoiner(join_mode="distribution_based_rank_fusion")
+        documents_1 = [
+            Document(content="a", score=0.2),
+            Document(content="b", score=0.2),
+            Document(content="c", score=0.2),
+        ]
+        documents_2 = [
+            Document(content="d", score=0.5),
+            Document(content="e", score=0.8),
+            Document(content="f", score=1.1, meta={"key": "value"}),
+            Document(content="g", score=0.3),
+            Document(content="a", score=0.3),
+        ]
+        output = joiner.run([documents_1, documents_2])
+        assert len(output["documents"]) == 7
+        expected_document_ids = [
+            doc.id
+            for doc in [
+                Document(content="a", score=0),
+                Document(content="b", score=0),
+                Document(content="c", score=0),
+                Document(content="d", score=0.44),
+                Document(content="e", score=0.60),
+                Document(content="f", score=0.76, meta={"key": "value"}),
+                Document(content="g", score=0.33),
+            ]
+        ]
+        assert all(doc.id in expected_document_ids for doc in output["documents"])
+
     def test_run_with_top_k_in_run_method(self):
         joiner = DocumentJoiner()
         documents_1 = [Document(content="a"), Document(content="b"), Document(content="c")]