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0914f284bb
The cross encoder re-ranked results are much better for more distant queries. It does take more time with the cross-encoder re-ranking but it seems worth it to get more relevant results
71 lines
2.8 KiB
Python
71 lines
2.8 KiB
Python
#!/usr/bin/env python
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import json
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from sentence_transformers import SentenceTransformer, CrossEncoder, util
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import time
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import gzip
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import os
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import sys
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# We use the Bi-Encoder to encode all passages, so that we can use it with sematic search
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model_name = 'msmarco-MiniLM-L-6-v3'
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bi_encoder = SentenceTransformer(model_name)
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top_k = 100 # Number of passages we want to retrieve with the bi-encoder
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# The bi-encoder will retrieve 100 documents.
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# We use a cross-encoder, to re-rank the results list to improve the quality
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cross_encoder = CrossEncoder('cross-encoder/ms-marco-MiniLM-L-6-v2')
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# We split these articles into paragraphs and encode them with the bi-encoder
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notes_filepath = 'Notes.jsonl.gz'
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passages = []
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with gzip.open(notes_filepath, 'rt', encoding='utf8') as fIn:
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for line in fIn:
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data = json.loads(line.strip())
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passages.extend([f'{data["Title"]}\n{data["Body"] if "Body" in data else ""}'])
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print(f"Passages: {len(passages)}")
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# Here, we compute the corpus_embeddings from scratch (which can take a while depending on the GPU)
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corpus_embeddings = bi_encoder.encode(passages, convert_to_tensor=True, show_progress_bar=True)
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# This function will search all notes for passages that answer the query
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def search(query):
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print("Input question:", query)
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##### Sematic Search #####
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# Encode the query using the bi-encoder and find potentially relevant passages
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question_embedding = bi_encoder.encode(query, convert_to_tensor=True)
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#question_embedding = question_embedding.cuda()
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hits = util.semantic_search(question_embedding, corpus_embeddings, top_k=top_k)
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hits = hits[0] # Get the hits for the first query
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##### Re-Ranking #####
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# Now, score all retrieved passages with the cross_encoder
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cross_inp = [[query, passages[hit['corpus_id']]] for hit in hits]
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cross_scores = cross_encoder.predict(cross_inp)
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# Sort results by the cross-encoder scores
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for idx in range(len(cross_scores)):
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hits[idx]['cross-score'] = cross_scores[idx]
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# Output of top-5 hits from bi-encoder
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print("\n-------------------------\n")
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print("Top-3 Bi-Encoder Retrieval hits")
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hits = sorted(hits, key=lambda x: x['score'], reverse=True)
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for hit in hits[0:3]:
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print("\t{:.3f}\t{}".format(hit['score'], passages[hit['corpus_id']].replace("\n", " ")))
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# Output of top-5 hits from re-ranker
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print("\n-------------------------\n")
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print("Top-3 Cross-Encoder Re-ranker hits")
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hits = sorted(hits, key=lambda x: x['cross-score'], reverse=True)
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for hit in hits[0:3]:
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print("\t{:.3f}\t{}".format(hit['cross-score'], passages[hit['corpus_id']].replace("\n", " ")))
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while True:
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user_query = input("Enter your query: ")
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if user_query == "exit":
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exit(0)
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search(query = user_query)
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