/// <summary> Computes a score factor for a simple term and returns an explanation
/// for that score factor.
///
/// <p/>
/// The default implementation uses:
///
/// <pre>
/// idf(searcher.docFreq(term), searcher.maxDoc());
/// </pre>
///
/// Note that {@link Searcher#MaxDoc()} is used instead of
/// {@link Mono.Lucene.Net.Index.IndexReader#NumDocs()} because it is
/// proportional to {@link Searcher#DocFreq(Term)} , i.e., when one is
/// inaccurate, so is the other, and in the same direction.
///
/// </summary>
/// <param name="term">the term in question
/// </param>
/// <param name="searcher">the document collection being searched
/// </param>
/// <returns> an IDFExplain object that includes both an idf score factor
/// and an explanation for the term.
/// </returns>
/// <throws> IOException </throws>
public virtual IDFExplanation IdfExplain(Term term, Searcher searcher)
{
if (SupportedMethods.overridesTermIDF)
{
float idf = Idf(term, searcher);
return(new AnonymousClassIDFExplanation(idf, this));
}
int df = searcher.DocFreq(term);
int max = searcher.MaxDoc();
float idf2 = Idf(df, max);
return(new AnonymousClassIDFExplanation1(df, max, idf2, this));
}
/// <summary> Computes a score factor for a phrase.
///
/// <p/>
/// The default implementation sums the idf factor for
/// each term in the phrase.
///
/// </summary>
/// <param name="terms">the terms in the phrase
/// </param>
/// <param name="searcher">the document collection being searched
/// </param>
/// <returns> an IDFExplain object that includes both an idf
/// score factor for the phrase and an explanation
/// for each term.
/// </returns>
/// <throws> IOException </throws>
public virtual IDFExplanation idfExplain(System.Collections.ICollection terms, Searcher searcher)
{
if (SupportedMethods.overridesCollectionIDF)
{
float idf = Idf(terms, searcher);
return(new AnonymousClassIDFExplanation2(idf, this));
}
int max = searcher.MaxDoc();
float idf2 = 0.0f;
System.Text.StringBuilder exp = new System.Text.StringBuilder();
foreach (Term term in terms)
{
int df = searcher.DocFreq(term);
idf2 += Idf(df, max);
exp.Append(" ");
exp.Append(term.Text());
exp.Append("=");
exp.Append(df);
}
float fIdf = idf2;
return(new AnonymousClassIDFExplanation3(fIdf, exp, this));
}
public virtual float Idf(Term term, Searcher searcher)
{
return(Idf(searcher.DocFreq(term), searcher.MaxDoc()));
}
/// <summary> Computes a score factor for a phrase.
///
/// <p/>
/// The default implementation sums the idf factor for
/// each term in the phrase.
///
/// </summary>
/// <param name="terms">the terms in the phrase
/// </param>
/// <param name="searcher">the document collection being searched
/// </param>
/// <returns> an IDFExplain object that includes both an idf
/// score factor for the phrase and an explanation
/// for each term.
/// </returns>
/// <throws> IOException </throws>
public virtual IDFExplanation idfExplain(System.Collections.ICollection terms, Searcher searcher)
{
if (SupportedMethods.overridesCollectionIDF)
{
float idf = Idf(terms, searcher);
return new AnonymousClassIDFExplanation2(idf, this);
}
int max = searcher.MaxDoc();
float idf2 = 0.0f;
System.Text.StringBuilder exp = new System.Text.StringBuilder();
foreach (Term term in terms)
{
int df = searcher.DocFreq(term);
idf2 += Idf(df, max);
exp.Append(" ");
exp.Append(term.Text());
exp.Append("=");
exp.Append(df);
}
float fIdf = idf2;
return new AnonymousClassIDFExplanation3(fIdf, exp, this);
}
/// <summary> Computes a score factor for a simple term and returns an explanation
/// for that score factor.
///
/// <p/>
/// The default implementation uses:
///
/// <pre>
/// idf(searcher.docFreq(term), searcher.maxDoc());
/// </pre>
///
/// Note that {@link Searcher#MaxDoc()} is used instead of
/// {@link Mono.Lucene.Net.Index.IndexReader#NumDocs()} because it is
/// proportional to {@link Searcher#DocFreq(Term)} , i.e., when one is
/// inaccurate, so is the other, and in the same direction.
///
/// </summary>
/// <param name="term">the term in question
/// </param>
/// <param name="searcher">the document collection being searched
/// </param>
/// <returns> an IDFExplain object that includes both an idf score factor
/// and an explanation for the term.
/// </returns>
/// <throws> IOException </throws>
public virtual IDFExplanation IdfExplain(Term term, Searcher searcher)
{
if (SupportedMethods.overridesTermIDF)
{
float idf = Idf(term, searcher);
return new AnonymousClassIDFExplanation(idf, this);
}
int df = searcher.DocFreq(term);
int max = searcher.MaxDoc();
float idf2 = Idf(df, max);
return new AnonymousClassIDFExplanation1(df, max, idf2, this);
}
public virtual float Idf(Term term, Searcher searcher)
{
return Idf(searcher.DocFreq(term), searcher.MaxDoc());
}
