add support for Baidu yiyan (#2049)

### What problem does this PR solve?

add support for Baidu yiyan

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>

rag/llm/rerank_model.py

@@ -24,6 +24,7 @@ from abc import ABC
 import numpy as np
 from api.utils.file_utils import get_home_cache_dir
 from rag.utils import num_tokens_from_string, truncate
+import json
 
 def sigmoid(x):
     return 1 / (1 + np.exp(-x))
@@ -288,3 +289,25 @@ class SILICONFLOWRerank(Base):
             rank[indexs],
             response["meta"]["tokens"]["input_tokens"] + response["meta"]["tokens"]["output_tokens"],
         )
+
+
+class BaiduYiyanRerank(Base):
+    def __init__(self, key, model_name, base_url=None):
+        from qianfan.resources import Reranker
+
+        key = json.loads(key)
+        ak = key.get("yiyan_ak", "")
+        sk = key.get("yiyan_sk", "")
+        self.client = Reranker(ak=ak, sk=sk)
+        self.model_name = model_name
+
+    def similarity(self, query: str, texts: list):
+        res = self.client.do(
+            model=self.model_name,
+            query=query,
+            documents=texts,
+            top_n=len(texts),
+        ).body
+        rank = np.array([d["relevance_score"] for d in res["results"]])
+        indexs = [d["index"] for d in res["results"]]
+        return rank[indexs], res["usage"]["total_tokens"]