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

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and 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 Detail

    - #### 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)`

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