TF-IDF and BM25 Ranking

TextFieldIndex supports two ranking algorithms.

BM25

• Better default for mixed-length content
• Common search-engine ranking baseline
• Configurable with k1 and b

TF-IDF

• Simple and familiar
• Useful for debugging or comparison

import { RankingAlgorithm, TextFieldIndex } from "@tryformation/querylight-ts";

const bm25 = new TextFieldIndex(undefined, undefined, RankingAlgorithm.BM25);
const tfidf = new TextFieldIndex(undefined, undefined, RankingAlgorithm.TFIDF);

The docs browser keeps both indexes live and lets you switch between them from the toolbar.

Learn more

• TF-IDF on Wikipedia
• Okapi BM25 on Wikipedia
• The Probabilistic Relevance Framework: BM25 and Beyond