Method IdfExplain

IdfExplain(Term, Searcher)

Computes a score factor for a simple term and returns an explanation for that score factor.

The default implementation uses:

idf(searcher.docFreq(term), searcher.MaxDoc);

Note that MaxDoc is used instead of NumDocs() because it is proportional to DocFreq(Term) , i.e., when one is inaccurate, so is the other, and in the same direction.

Declaration
public virtual Explanation.IDFExplanation IdfExplain(Term term, Searcher searcher)
Parameters
Type Name Description
Term term

the term in question
Searcher searcher

the document collection being searched
Returns
Type Description
Explanation.IDFExplanation

an IDFExplain object that includes both an idf score factor and an explanation for the term.

IdfExplain(ICollection<Term>, Searcher)

Computes a score factor for a phrase.

The default implementation sums the idf factor for each term in the phrase.

Declaration
public virtual Explanation.IDFExplanation IdfExplain(ICollection<Term> terms, Searcher searcher)
Parameters
Type Name Description
ICollection<Term> terms

the terms in the phrase
Searcher searcher

the document collection being searched
Returns
Type Description
Explanation.IDFExplanation

an IDFExplain object that includes both an idf score factor for the phrase and an explanation for each term.