From d6ce5be4889e462fa69968feb90f8ebad30cdb0f Mon Sep 17 00:00:00 2001
From: Gustaf Rydholm <gustaf.rydholm@gmail.com>
Date: Tue, 23 Apr 2024 00:49:36 +0200
Subject: Add reranking

---
 rag/generator/cohere.py | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/rag/generator/cohere.py b/rag/generator/cohere.py
index 16dfe88..3499e3b 100644
--- a/rag/generator/cohere.py
+++ b/rag/generator/cohere.py
@@ -1,6 +1,6 @@
 import os
 from dataclasses import asdict
-from typing import Any, Dict, Generator, List
+from typing import Any, Generator
 
 import cohere
 from loguru import logger as log
@@ -13,8 +13,23 @@ class Cohere(metaclass=AbstractGenerator):
     def __init__(self) -> None:
         self.client = cohere.Client(os.environ["COHERE_API_KEY"])
 
+    def rerank(self, prompt: Prompt):
+        response = self.client.rerank(
+            model="rerank-english-v3.0",
+            query=prompt.query,
+            documents=[d.text for d in prompt.documents],
+            top_n=3,
+        )
+        ranking = list(
+            filter(lambda x: x.relevance_score > 0.5, response.results)
+        )
+        prompt.documents = [prompt.documents[r.index] for r in ranking]
+        return prompt
+
     def generate(self, prompt: Prompt) -> Generator[Any, Any, Any]:
         log.debug("Generating answer from cohere...")
+        if prompt.documents:
+            prompt = self.rerank(prompt)
         query = f"{prompt.query}\n\n{ANSWER_INSTRUCTION}"
         for event in self.client.chat_stream(
             message=query,
@@ -27,21 +42,3 @@ class Cohere(metaclass=AbstractGenerator):
                 yield event.citations
             elif event.event_type == "stream-end":
                 yield event.finish_reason
-
-    def chat(
-        self, prompt: Prompt, messages: List[Dict[str, str]]
-    ) -> Generator[Any, Any, Any]:
-        log.debug("Generating answer from cohere...")
-        query = f"{prompt.query}\n\n{ANSWER_INSTRUCTION}"
-        for event in self.client.chat_stream(
-            message=query,
-            documents=[asdict(d) for d in prompt.documents],
-            chat_history=messages,
-            prompt_truncation="AUTO",
-        ):
-            if event.event_type == "text-generation":
-                yield event.text
-            # elif event.event_type == "citation-generation":
-            #     yield event.citations
-            elif event.event_type == "stream-end":
-                yield event.finish_reason
-- 
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