问题
I'm conducting a research using elasticsearch. I was planning to use cosine similarity but I noted that it is unavailable and instead we have BM25 as default scoring function.
Is there a reason for that? Is cosine similarity improper for querying documents? Why was BM25 chosen as default? Thanks
回答1:
Longtime elasticsearch use TF/IDF algorithm to find similarity in queries. But number versions ago is changed to BM25 as more efficient. You can read the information in the documentation. And good article explains what is elastic search and how to the similarity in ES.
You can also write a custom algorithm to elasticsearch. Here a good article about how to do.
来源：https://stackoverflow.com/questions/55174358/how-cosine-similarity-differs-from-okapi-bm25