Add merge entities

README.md

@@ -849,6 +849,76 @@ All operations are available in both synchronous and asynchronous versions. The
 
 These operations maintain data consistency across both the graph database and vector database components, ensuring your knowledge graph remains coherent.
 
+## Entity Merging
+
+<details>
+<summary> <b>Merge Entities and Their Relationships</b> </summary>
+
+LightRAG now supports merging multiple entities into a single entity, automatically handling all relationships:
+
+```python
+# Basic entity merging
+rag.merge_entities(
+    source_entities=["Artificial Intelligence", "AI", "Machine Intelligence"],
+    target_entity="AI Technology"
+)
+```
+
+With custom merge strategy:
+
+```python
+# Define custom merge strategy for different fields
+rag.merge_entities(
+    source_entities=["John Smith", "Dr. Smith", "J. Smith"],
+    target_entity="John Smith",
+    merge_strategy={
+        "description": "concatenate",  # Combine all descriptions
+        "entity_type": "keep_first",   # Keep the entity type from the first entity
+        "source_id": "join_unique"     # Combine all unique source IDs
+    }
+)
+```
+
+With custom target entity data:
+
+```python
+# Specify exact values for the merged entity
+rag.merge_entities(
+    source_entities=["New York", "NYC", "Big Apple"],
+    target_entity="New York City",
+    target_entity_data={
+        "entity_type": "LOCATION",
+        "description": "New York City is the most populous city in the United States.",
+    }
+)
+```
+
+Advanced usage combining both approaches:
+
+```python
+# Merge company entities with both strategy and custom data
+rag.merge_entities(
+    source_entities=["Microsoft Corp", "Microsoft Corporation", "MSFT"],
+    target_entity="Microsoft",
+    merge_strategy={
+        "description": "concatenate",  # Combine all descriptions
+        "source_id": "join_unique"     # Combine source IDs
+    },
+    target_entity_data={
+        "entity_type": "ORGANIZATION",
+    }
+)
+```
+
+When merging entities:
+* All relationships from source entities are redirected to the target entity
+* Duplicate relationships are intelligently merged
+* Self-relationships (loops) are prevented
+* Source entities are removed after merging
+* Relationship weights and attributes are preserved
+
+</details>
+
 ## Cache
 
 <details>