Package org.apache.lucene.queries.function

# Class IndexReaderFunctions

java.lang.Object
org.apache.lucene.queries.function.IndexReaderFunctions

public final class IndexReaderFunctions extends Object
Class exposing static helper methods for generating DoubleValuesSource instances over some IndexReader statistics

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static DoubleValuesSource`
  `docCount(String field)`
  Creates a constant value source returning the docCount for a given field
  `static DoubleValuesSource`
  `docFreq(Term term)`
  Creates a constant value source returning the docFreq of a given term
  `static DoubleValuesSource`
  `maxDoc()`
  Creates a constant value source returning the index's maxDoc
  `static DoubleValuesSource`
  `numDeletedDocs()`
  Creates a constant value source returning the number of deleted docs in the index
  `static DoubleValuesSource`
  `numDocs()`
  Creates a constant value source returning the index's numDocs
  `static DoubleValuesSource`
  `sumDocFreq(String field)`
  Creates a constant value source returning the sumDocFreq for a given field
  `static LongValuesSource`
  `sumTotalTermFreq(String field)`
  Creates a constant value source returning the sumTotalTermFreq for a field
  `static DoubleValuesSource`
  `termFreq(Term term)`
  Creates a value source that returns the term freq of a given term for each document
  `static DoubleValuesSource`
  `totalTermFreq(Term term)`
  Creates a constant value source returning the totalTermFreq for a given term

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Method Details

  - ### docFreq

    public static DoubleValuesSource docFreq(Term term)
    Creates a constant value source returning the docFreq of a given term
    See Also:
      - `IndexReader.docFreq(Term)`

  - ### maxDoc

    public static DoubleValuesSource maxDoc()
    Creates a constant value source returning the index's maxDoc
    See Also:
      - `IndexReader.maxDoc()`

  - ### numDocs

    public static DoubleValuesSource numDocs()
    Creates a constant value source returning the index's numDocs
    See Also:
      - `IndexReader.numDocs()`

  - ### numDeletedDocs

    public static DoubleValuesSource numDeletedDocs()
    Creates a constant value source returning the number of deleted docs in the index
    See Also:
      - `IndexReader.numDeletedDocs()`

  - ### sumTotalTermFreq

    public static LongValuesSource sumTotalTermFreq(String field)
    Creates a constant value source returning the sumTotalTermFreq for a field
    See Also:
      - `IndexReader.getSumTotalTermFreq(String)`

  - ### termFreq

    public static DoubleValuesSource termFreq(Term term)
    Creates a value source that returns the term freq of a given term for each document
    See Also:
      - `PostingsEnum.freq()`

  - ### totalTermFreq

    public static DoubleValuesSource totalTermFreq(Term term)
    Creates a constant value source returning the totalTermFreq for a given term
    See Also:
      - `IndexReader.totalTermFreq(Term)`

  - ### sumDocFreq

    public static DoubleValuesSource sumDocFreq(String field)
    Creates a constant value source returning the sumDocFreq for a given field
    See Also:
      - `IndexReader.getSumDocFreq(String)`

  - ### docCount

    public static DoubleValuesSource docCount(String field)
    Creates a constant value source returning the docCount for a given field
    See Also:
      - `IndexReader.getDocCount(String)`