Fix: evolution flows for test generation (#602)

fixes : #599

Author: shahules786

src/ragas/testset/evolutions.py

@@ -63,12 +63,23 @@ class Evolution:
 
     @staticmethod
     def merge_nodes(nodes: CurrentNodes) -> Node:
-        return Node(
+        # TODO: while merging merge according to the order of documents
+        # if any nodes from same document take account their page order
+
+        new_node = Node(
             doc_id="merged",
             page_content="\n".join(n.page_content for n in nodes.nodes),
             keyphrases=[phrase for n in nodes.nodes for phrase in n.keyphrases],
         )
 
+        embed_dim = len(nodes.nodes[0].embedding) if nodes.nodes[0].embedding else None
+        if embed_dim:
+            node_embeddings = np.array([n.embedding for n in nodes.nodes]).reshape(
+                -1, embed_dim
+            )
+            new_node.embedding = np.average(node_embeddings, axis=0)
+        return new_node
+
     def init(self, is_async: bool = True, run_config: t.Optional[RunConfig] = None):
         self.is_async = is_async
         if run_config is None:
@@ -191,7 +202,10 @@ async def generate_datarow(
                 root_node=current_nodes.root_node, nodes=current_nodes.nodes
             )
         else:
-            relevant_context = current_nodes
+            selected_nodes = [current_nodes.nodes[i] for i in relevant_context_indices]
+            relevant_context = CurrentNodes(
+                root_node=selected_nodes[0], nodes=selected_nodes
+            )
 
         merged_nodes = self.merge_nodes(relevant_context)
         results = await self.generator_llm.generate(
@@ -207,7 +221,7 @@ async def generate_datarow(
 
         return DataRow(
             question=question,
-            contexts=[n.page_content for n in current_nodes.nodes],
+            contexts=[n.page_content for n in relevant_context.nodes],
             ground_truth="" if answer is None else answer,
             evolution_type=evolution_type,
         )
@@ -253,7 +267,7 @@ async def _aevolve(
         assert self.question_filter is not None, "question_filter cannot be None"
 
         merged_node = self.merge_nodes(current_nodes)
-        passed = await self.node_filter.filter(current_nodes.root_node)
+        passed = await self.node_filter.filter(merged_node)
         if not passed["score"]:
             nodes = self.docstore.get_random_nodes(k=1)
             new_current_nodes = CurrentNodes(root_node=nodes[0], nodes=nodes)
@@ -334,16 +348,19 @@ async def _acomplex_evolution(
         assert self.question_filter is not None, "question_filter cannot be None"
         assert self.se is not None, "simple evolution cannot be None"
 
-        simple_question, _, _ = await self.se._aevolve(current_tries, current_nodes)
+        simple_question, current_nodes, _ = await self.se._aevolve(
+            current_tries, current_nodes
+        )
         logger.debug(
             "[%s] simple question generated: %s",
             self.__class__.__name__,
             simple_question,
         )
 
+        merged_node = self.merge_nodes(current_nodes)
         result = await self.generator_llm.generate(
             prompt=question_prompt.format(
-                question=simple_question, context=current_nodes.root_node.page_content
+                question=simple_question, context=merged_node.page_content
             )
         )
         reasoning_question = result.generations[0][0].text.strip()
@@ -409,42 +426,53 @@ async def _aevolve(
         assert self.question_filter is not None, "question_filter cannot be None"
         assert self.se is not None, "simple evolution cannot be None"
 
-        simple_question, _, _ = await self.se._aevolve(current_tries, current_nodes)
+        simple_question, current_nodes, _ = await self.se._aevolve(
+            current_tries, current_nodes
+        )
         logger.debug(
             "[MultiContextEvolution] simple question generated: %s", simple_question
         )
-
         # find a similar node and generate a question based on both
-        similar_node = self.docstore.get_similar(current_nodes.root_node)
+        merged_node = self.merge_nodes(current_nodes)
+        similar_node = self.docstore.get_similar(merged_node, top_k=1)
         if similar_node == []:
             # retry
-            current_nodes = self.se._get_more_adjacent_nodes(current_nodes)
+            new_random_nodes = self.docstore.get_random_nodes(k=1)
+            current_nodes = CurrentNodes(
+                root_node=new_random_nodes[0], nodes=new_random_nodes
+            )
             return await self.aretry_evolve(current_tries, current_nodes)
+        else:
+            assert isinstance(similar_node[0], Node), "similar_node must be a Node"
+            current_nodes = CurrentNodes(
+                root_node=merged_node, nodes=[merged_node, similar_node[0]]
+            )
 
         prompt = self.multi_context_question_prompt.format(
             question=simple_question,
-            context1=current_nodes.root_node.page_content,
-            context2=similar_node,
+            context1=merged_node.page_content,
+            context2=similar_node[0].page_content,
         )
         results = await self.generator_llm.generate(prompt=prompt)
         question = results.generations[0][0].text.strip()
         logger.debug(
             "[MultiContextEvolution] multicontext question generated: %s", question
         )
 
+        if not await self.question_filter.filter(question):
+            # retry
+            current_nodes = self.se._get_more_adjacent_nodes(current_nodes)
+            return await self.aretry_evolve(current_tries, current_nodes)
+
         # compress the question
         compressed_question = await self._transform_question(
             prompt=self.compress_question_prompt, question=question
         )
         logger.debug(
-            "[MultiContextEvolution] multicontext question compressed: %s", question
+            "[MultiContextEvolution] multicontext question compressed: %s",
+            compressed_question,
         )
 
-        if not await self.question_filter.filter(compressed_question):
-            # retry
-            current_nodes = self.se._get_more_adjacent_nodes(current_nodes)
-            return await self.aretry_evolve(current_tries, current_nodes)
-
         assert self.evolution_filter is not None, "evolution filter cannot be None"
         if await self.evolution_filter.filter(simple_question, compressed_question):
             # retry