Package org.apache.lucene.classification.document

# Class KNearestNeighborDocumentClassifier

java.lang.Object
org.apache.lucene.classification.KNearestNeighborClassifier
org.apache.lucene.classification.document.KNearestNeighborDocumentClassifier

All Implemented Interfaces:
  `Classifier<BytesRef>`, `DocumentClassifier<BytesRef>`

public class KNearestNeighborDocumentClassifier extends KNearestNeighborClassifier implements DocumentClassifier<BytesRef>
A k-Nearest Neighbor Document classifier (see `http://en.wikipedia.org/wiki/K-nearest_neighbors`) based on `MoreLikeThis` .

WARNING: This API is experimental and might change in incompatible ways in the next release.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected final Map<String,Analyzer>`
  `field2analyzer`
  map of per field analyzers

  ### Fields inherited from class org.apache.lucene.classification.KNearestNeighborClassifier

  `classFieldName, indexSearcher, k, mlt, query, textFieldNames`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `KNearestNeighborDocumentClassifier(IndexReader indexReader, Similarity similarity, Query query, int k, int minDocsFreq, int minTermFreq, String classFieldName, Map<String,Analyzer> field2analyzer, String... textFieldNames)`
  Creates a `KNearestNeighborClassifier`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `ClassificationResult<BytesRef>`
  `assignClass(Document document)`
  Assign a class (with score) to the given `Document`
  `List<ClassificationResult<BytesRef>>`
  `getClasses(Document document)`
  Get all the classes (sorted by score, descending) assigned to the given `Document`.
  `List<ClassificationResult<BytesRef>>`
  `getClasses(Document document, int max)`
  Get the first `max` classes (sorted by score, descending) assigned to the given text String.

  ### Methods inherited from class org.apache.lucene.classification.KNearestNeighborClassifier

  `assignClass, buildListFromTopDocs, classifyFromTopDocs, getClasses, getClasses, toString`

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

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

- ## Field Details

  - ### field2analyzer

    protected final Map<String,Analyzer> field2analyzer
    map of per field analyzers

- ## Constructor Details

  - ### KNearestNeighborDocumentClassifier

    public KNearestNeighborDocumentClassifier(IndexReader indexReader, Similarity similarity, Query query, int k, int minDocsFreq, int minTermFreq, String classFieldName, Map<String,Analyzer> field2analyzer, String... textFieldNames) throws IOException
    Creates a `KNearestNeighborClassifier`.
    Parameters:
      `indexReader` - the reader on the index to be used for classification
      `similarity` - the `Similarity` to be used by the underlying `IndexSearcher` or `null` (defaults to `BM25Similarity`)
      `query` - a `Query` to eventually filter the docs used for training the classifier, or `null` if all the indexed docs should be used
      `k` - the no. of docs to select in the MLT results to find the nearest neighbor
      `minDocsFreq` - `MoreLikeThis.minDocFreq` parameter
      `minTermFreq` - `MoreLikeThis.minTermFreq` parameter
      `classFieldName` - the name of the field used as the output for the classifier
      `field2analyzer` - map with key a field name and the related {org.apache.lucene.analysis.Analyzer}
      `textFieldNames` - the name of the fields used as the inputs for the classifier, they can contain boosting indication e.g. title^10
    Throws:
      `IOException`

- ## Method Details

  - ### assignClass

    public ClassificationResult<BytesRef> assignClass(Document document) throws IOException
    Description copied from interface: `DocumentClassifier`
    Assign a class (with score) to the given `Document`
    Specified by:
      `assignClass` in interface `DocumentClassifier<BytesRef>`
    Parameters:
      `document` - a `Document` to be classified. Fields are considered features for the classification.
    Returns:
      a `ClassificationResult` holding assigned class of type `T` and score
    Throws:
      `IOException` - If there is a low-level I/O error.

  - ### getClasses

    public List<ClassificationResult<BytesRef>> getClasses(Document document) throws IOException
    Description copied from interface: `DocumentClassifier`
    Get all the classes (sorted by score, descending) assigned to the given `Document`.
    Specified by:
      `getClasses` in interface `DocumentClassifier<BytesRef>`
    Parameters:
      `document` - a `Document` to be classified. Fields are considered features for the classification.
    Returns:
      the whole list of `ClassificationResult`, the classes and scores. Returns `null` if the classifier can't make lists.
    Throws:
      `IOException` - If there is a low-level I/O error.

  - ### getClasses

    public List<ClassificationResult<BytesRef>> getClasses(Document document, int max) throws IOException
    Description copied from interface: `DocumentClassifier`
    Get the first `max` classes (sorted by score, descending) assigned to the given text String.
    Specified by:
      `getClasses` in interface `DocumentClassifier<BytesRef>`
    Parameters:
      `document` - a `Document` to be classified. Fields are considered features for the classification.
      `max` - the number of return list elements
    Returns:
      the whole list of `ClassificationResult`, the classes and scores. Cut for "max" number of elements. Returns `null` if the classifier can't make lists.
    Throws:
      `IOException` - If there is a low-level I/O error.