org.apache.lucene.search.similarities

## Class BasicStats

- java.lang.Object
- - org.apache.lucene.search.similarities.Similarity.SimWeight
  - - org.apache.lucene.search.similarities.BasicStats

- Direct Known Subclasses:
    LMSimilarity.LMStats

      public class BasicStats
      extends Similarity.SimWeight

  Stores all statistics commonly used ranking methods.
  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected float` | `avgFieldLength` The average field length.
    `protected long` | `docFreq` The document frequency.
    `protected long` | `numberOfDocuments` The number of documents.
    `protected long` | `numberOfFieldTokens` The total number of tokens in the field.
    `protected float` | `queryBoost` Query's inner boost.
    `protected float` | `topLevelBoost` Any outer query's boost.
    `protected float` | `totalBoost` For most Similarities, the immediate and the top level query boosts are not handled differently.
    `protected long` | `totalTermFreq` The total number of occurrences of this term across all documents.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `BasicStats(String field, float queryBoost)` Constructor.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `float` | `getAvgFieldLength()` Returns the average field length.
    `long` | `getDocFreq()` Returns the document frequency.
    `long` | `getNumberOfDocuments()` Returns the number of documents.
    `long` | `getNumberOfFieldTokens()` Returns the total number of tokens in the field.
    `float` | `getTotalBoost()` Returns the total boost.
    `long` | `getTotalTermFreq()` Returns the total number of occurrences of this term across all documents.
    `float` | `getValueForNormalization()` The square of the raw normalization value.
    `void` | `normalize(float queryNorm, float topLevelBoost)` No normalization is done.
    `protected float` | `rawNormalizationValue()` Computes the raw normalization value.
    `void` | `setAvgFieldLength(float avgFieldLength)` Sets the average field length.
    `void` | `setDocFreq(long docFreq)` Sets the document frequency.
    `void` | `setNumberOfDocuments(long numberOfDocuments)` Sets the number of documents.
    `void` | `setNumberOfFieldTokens(long numberOfFieldTokens)` Sets the total number of tokens in the field.
    `void` | `setTotalTermFreq(long totalTermFreq)` Sets the total number of occurrences of this term across all documents.

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

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

- - ### Field Detail

    - #### numberOfDocuments

          protected long numberOfDocuments

      The number of documents.

    - #### numberOfFieldTokens

          protected long numberOfFieldTokens

      The total number of tokens in the field.

    - #### avgFieldLength

          protected float avgFieldLength

      The average field length.

    - #### docFreq

          protected long docFreq

      The document frequency.

    - #### totalTermFreq

          protected long totalTermFreq

      The total number of occurrences of this term across all documents.

    - #### queryBoost

          protected final float queryBoost

      Query's inner boost.

    - #### topLevelBoost

          protected float topLevelBoost

      Any outer query's boost.

    - #### totalBoost

          protected float totalBoost

      For most Similarities, the immediate and the top level query boosts are not handled differently. Hence, this field is just the product of the other two.

  - ### Constructor Detail

    - #### BasicStats

          public BasicStats(String field,
                    float queryBoost)

      Constructor. Sets the query boost.

  - ### Method Detail

    - #### getNumberOfDocuments

          public long getNumberOfDocuments()

      Returns the number of documents.

    - #### setNumberOfDocuments

          public void setNumberOfDocuments(long numberOfDocuments)

      Sets the number of documents.

    - #### getNumberOfFieldTokens

          public long getNumberOfFieldTokens()

      Returns the total number of tokens in the field.
      See Also:
        `Terms.getSumTotalTermFreq()`

    - #### setNumberOfFieldTokens

          public void setNumberOfFieldTokens(long numberOfFieldTokens)

      Sets the total number of tokens in the field.
      See Also:
        `Terms.getSumTotalTermFreq()`

    - #### getAvgFieldLength

          public float getAvgFieldLength()

      Returns the average field length.

    - #### setAvgFieldLength

          public void setAvgFieldLength(float avgFieldLength)

      Sets the average field length.

    - #### getDocFreq

          public long getDocFreq()

      Returns the document frequency.

    - #### setDocFreq

          public void setDocFreq(long docFreq)

      Sets the document frequency.

    - #### getTotalTermFreq

          public long getTotalTermFreq()

      Returns the total number of occurrences of this term across all documents.

    - #### setTotalTermFreq

          public void setTotalTermFreq(long totalTermFreq)

      Sets the total number of occurrences of this term across all documents.

    - #### getValueForNormalization

          public float getValueForNormalization()

      The square of the raw normalization value.
      Specified by:
        `getValueForNormalization` in class `Similarity.SimWeight`
      See Also:
        `rawNormalizationValue()`

    - #### rawNormalizationValue

          protected float rawNormalizationValue()

      Computes the raw normalization value. This basic implementation returns the query boost. Subclasses may override this method to include other factors (such as idf), or to save the value for inclusion in `normalize(float, float)`, etc.

    - #### normalize

          public void normalize(float queryNorm,
                       float topLevelBoost)

      No normalization is done. `topLevelBoost` is saved in the object, however.
      Specified by:
        `normalize` in class `Similarity.SimWeight`

    - #### getTotalBoost

          public float getTotalBoost()

      Returns the total boost.

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