Concept逆文档频率 / Inverse Document Frequency
IDF
A metric in information retrieval that measures how rare a term is. The lower the document frequency, the higher the weight; it is a core component of ranking algorithms such as BM25.
Timeline (last 90 days)
Sep 7
The standard form of IDF, log(N/df), essentially measures the amount of information or surprise carried by a word, and has a deep connection with the concept of self-information I(x)=-log(P(x)) in information theory.
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