23RAG7 / retrieval.py
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import json
import numpy as np
from langchain.schema import Document
import faiss
from rank_bm25 import BM25Okapi
from data_processing import embedding_model
from sentence_transformers import CrossEncoder
#import string
# import nltk
# nltk.download('punkt')
# nltk.download('punkt_tab')
from nltk.tokenize import word_tokenize
reranker = CrossEncoder("cross-encoder/ms-marco-MiniLM-L-6-v2")
retrieved_docs = None
# Tokenize the documents and remove punctuation
# def preprocess(doc):
# return [word.lower() for word in word_tokenize(doc) if word not in string.punctuation]
def retrieve_documents_hybrid(query, q_dataset, top_k=5):
with open( f"data_local/{q_dataset}_chunked_docs.json", "r") as f:
chunked_documents = json.load(f) # Contains all documents for this dataset
faiss_index_path = f"data_local/{q_dataset}_quantized.faiss"
index = faiss.read_index(faiss_index_path)
# Tokenize documents for BM25
tokenized_docs = [doc.split() for doc in chunked_documents]
bm25 = BM25Okapi(tokenized_docs)
query_embedding = np.array(embedding_model.embed_documents([query]), dtype=np.float32)
query_embedding = query_embedding.reshape(1, -1)
# FAISS Search
_, faiss_indices = index.search(query_embedding, top_k)
faiss_docs = [chunked_documents[i] for i in faiss_indices[0]]
# BM25 Search
tokenized_query = query.split() #preprocess(query)
bm25_scores = bm25.get_scores(tokenized_query)
bm25_top_indices = np.argsort(bm25_scores)[::-1][:top_k]
bm25_docs = [chunked_documents[i] for i in bm25_top_indices]
# Combine FAISS + BM25 scores and retrieve docs
# combined_results = set(bm25_top_indices).union(set(faiss_indices[0]))
# combined_scores = rerank_docs_bm25faiss_scores(combined_results,bm25_scores, faiss_distances,faiss_indices)
# reranked_docs = [chunked_documents[result[0]] for result in combined_scores[:top_k]]
# Merge FAISS + BM25 Results and re-rank
retrieved_docs = list(set(faiss_docs + bm25_docs))[:top_k]
reranked_docs = rerank_documents(query, retrieved_docs)
return reranked_docs
def rerank_docs_bm25faiss_scores(combined_results_,bm25_scores_, faiss_distances_,faiss_indices_):
final_results = []
for idx in combined_results_:
# Combine BM25 score and FAISS score for ranking (this could be more sophisticated)
bm25_score = bm25_scores_[idx]
faiss_score = 1 / (1 + faiss_distances_[0][np.where(faiss_indices_[0] == idx)]) # Inverse distance for relevance
final_results.append((idx, bm25_score, faiss_score))
# Sort final results by combined score (you can adjust the ranking strategy here)
final_results.sort(key=lambda x: (x[1] + x[2]), reverse=True)
return final_results
# Retrieval Function
# def retrieve_documents(query, top_k=5):
# query_dataset = find_query_dataset(query)
# #index, chunk_docs = load_data_from_faiss(query)
# with open( f"data_local/{query_dataset}_chunked_docs.json", "r") as f:
# documents = json.load(f) # Contains all documents for this dataset
# faiss_index_path = f"data_local/{query_dataset}_quantized.faiss"
# index = faiss.read_index(faiss_index_path)
# query_embedding = np.array(embedding_model.embed_documents([query]), dtype=np.float32)
# _, nearest_indices = index.search(query_embedding, top_k)
# retrieved_docs = [Document(page_content=documents[i]) for i in nearest_indices[0]]
# return retrieved_docs
def remove_duplicate_documents(documents):
unique_documents = []
seen_documents = set()
for doc in documents:
doc_content = doc.page_content
if doc_content not in seen_documents:
unique_documents.append(doc)
seen_documents.add(doc_content)
return unique_documents
def find_query_dataset(query):
index = faiss.read_index("data_local/question_quantized.faiss")
with open("data_local/dataset_mapping.json", "r") as f:
dataset_names = json.load(f)
question_embedding = np.array(embedding_model.embed_documents([query]), dtype=np.float32)
_, nearest_index = index.search(question_embedding, 1)
best_dataset = dataset_names[nearest_index[0][0]]
return best_dataset
def rerank_documents(query, retrieved_docs):
doc_texts = [doc for doc in retrieved_docs]
scores = reranker.predict([[query, doc] for doc in doc_texts])
ranked_docs = [doc for _, doc in sorted(zip(scores, retrieved_docs), reverse=True)]
return ranked_docs[:5] # Return top k most relevant