C# Lucene.Net.Index.IndexReader.NumDocs方法代码示例

		/// <summary> Extracts all terms texts of a given Query into an array of WeightedTerms
		/// 
		/// </summary>
		/// <param name="query">     Query to extract term texts from
		/// </param>
		/// <param name="reader">used to compute IDF which can be used to a) score selected fragments better 
		/// b) use graded highlights eg chaning intensity of font color
		/// </param>
		/// <param name="fieldName">the field on which Inverse Document Frequency (IDF) calculations are based
		/// </param>
		/// <returns> an array of the terms used in a query, plus their weights.
		/// </returns>
		public static WeightedTerm[] GetIdfWeightedTerms(Query query, IndexReader reader, System.String fieldName)
		{
			WeightedTerm[] terms = GetTerms(query, false, fieldName);
			int totalNumDocs = reader.NumDocs();
			for (int i = 0; i < terms.Length; i++)
			{
				try
				{
					int docFreq = reader.DocFreq(new Term(fieldName, terms[i].term));
					//IDF algorithm taken from DefaultSimilarity class
					float idf = (float) (System.Math.Log((float) totalNumDocs / (double) (docFreq + 1)) + 1.0);
					terms[i].weight *= idf;
				}
				catch (System.IO.IOException e)
				{
					//ignore 
				}
			}
			return terms;
		}

			public virtual Explanation Explain(IndexReader reader, int doc)
			{
				
				ComplexExplanation result = new ComplexExplanation();
				result.SetDescription("weight(" + GetQuery() + " in " + doc + "), product of:");
				
				Explanation idfExpl = new Explanation(idf, "idf(docFreq=" + reader.DocFreq(Enclosing_Instance.term) + ", numDocs=" + reader.NumDocs() + ")");
				
				// explain query weight
				Explanation queryExpl = new Explanation();
				queryExpl.SetDescription("queryWeight(" + GetQuery() + "), product of:");
				
				Explanation boostExpl = new Explanation(Enclosing_Instance.GetBoost(), "boost");
				if (Enclosing_Instance.GetBoost() != 1.0f)
					queryExpl.AddDetail(boostExpl);
				queryExpl.AddDetail(idfExpl);
				
				Explanation queryNormExpl = new Explanation(queryNorm, "queryNorm");
				queryExpl.AddDetail(queryNormExpl);
				
				queryExpl.SetValue(boostExpl.GetValue() * idfExpl.GetValue() * queryNormExpl.GetValue());
				
				result.AddDetail(queryExpl);
				
				// explain field weight
				System.String field = Enclosing_Instance.term.Field();
				ComplexExplanation fieldExpl = new ComplexExplanation();
				fieldExpl.SetDescription("fieldWeight(" + Enclosing_Instance.term + " in " + doc + "), product of:");
				
				Explanation tfExpl = Scorer(reader).Explain(doc);
				fieldExpl.AddDetail(tfExpl);
				fieldExpl.AddDetail(idfExpl);
				
				Explanation fieldNormExpl = new Explanation();
				byte[] fieldNorms = reader.Norms(field);
				float fieldNorm = fieldNorms != null ? Similarity.DecodeNorm(fieldNorms[doc]) : 0.0f;
				fieldNormExpl.SetValue(fieldNorm);
				fieldNormExpl.SetDescription("fieldNorm(field=" + field + ", doc=" + doc + ")");
				fieldExpl.AddDetail(fieldNormExpl);
				
				fieldExpl.SetMatch(tfExpl.IsMatch());
				fieldExpl.SetValue(tfExpl.GetValue() * idfExpl.GetValue() * fieldNormExpl.GetValue());
				
				result.AddDetail(fieldExpl);
				System.Boolean tempAux = fieldExpl.GetMatch();
				result.SetMatch(tempAux);
				
				// combine them
				result.SetValue(queryExpl.GetValue() * fieldExpl.GetValue());
				
				if (queryExpl.GetValue() == 1.0f)
					return fieldExpl;
				
				return result;
			}