feat(RAG):add tree retriever based on document directory level (#2669)

examples/rag/doc_tree_retriever_example.py

@@ -0,0 +1,36 @@
+import asyncio
+
+from dbgpt.model.proxy import DeepseekLLMClient
+from dbgpt.rag.knowledge.base import ChunkStrategy
+from dbgpt.rag.transformer.keyword_extractor import KeywordExtractor
+from dbgpt_ext.rag import ChunkParameters
+from dbgpt_ext.rag.knowledge import KnowledgeFactory
+from dbgpt_ext.rag.retriever.doc_tree import DocTreeRetriever
+
+
+async def main():
+    knowledge = KnowledgeFactory.from_file_path("../../docs/docs/awel/awel.md")
+    chunk_parameters = ChunkParameters(
+        chunk_strategy=ChunkStrategy.CHUNK_BY_MARKDOWN_HEADER.name
+    )
+    docs = knowledge.load()
+    docs = knowledge.extract(docs, chunk_parameters)
+    llm_client = DeepseekLLMClient(api_key="your_api_key")
+    keyword_extractor = KeywordExtractor(
+        llm_client=llm_client, model_name="deepseek-chat"
+    )
+    # doc tree retriever retriever
+    retriever = DocTreeRetriever(
+        docs=docs,
+        top_k=10,
+        keywords_extractor=keyword_extractor,
+        with_content=False,
+    )
+    tree_index = retriever._tree_indexes[0]
+    nodes = await retriever.aretrieve("Introduce awel Operators")
+    for node in nodes:
+        tree_index.display_tree(node)
+
+
+if __name__ == "__main__":
+    asyncio.run(main())