idfExplain
Computes a score factor for a simple term and returns an explanation for that score factor.
The default implementation uses:
idf(docFreq, docCount);*
Note that CollectionStatistics.docCount is used instead of because also is used, and when the latter is inaccurate, so is , and in the same direction. In addition, does not skew when fields are sparse.
Return
an Explain object that includes both an idf score factor and an explanation for the term.
Parameters
collection-level statistics
term-level statistics for the term
Computes a score factor for a phrase.
The default implementation sums the idf factor for each term in the phrase.
Return
an Explain object that includes both an idf score factor for the phrase and an explanation for each term.
Parameters
collection-level statistics
term-level statistics for the terms in the phrase