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TF-IDF

Weights a word by its frequency in a document against its rarity across the corpus.

Formula

\text{tfidf} = tf \cdot \log\dfrac{N}{df}

Variables

tfTerm frequency

NTotal documents

dfDocuments containing the term

Example

Common words get low weight, rare terms high

Did You Know?

TF-IDF was the backbone of search engines and text mining for decades before embeddings.

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