## org.apache.lucene.classification
Class KNearestNeighborClassifier

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

All Implemented Interfaces:
  Classifier<BytesRef>

    public class KNearestNeighborClassifier

extends Object
implements Classifier<BytesRef>

A k-Nearest Neighbor 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.

Constructor Summary
`KNearestNeighborClassifier(int k)` Create a `Classifier` using kNN algorithm

Method Summary
`ClassificationResult<BytesRef>` `assignClass(String text)` Assign a class (with score) to the given text String
`void` `train(AtomicReader atomicReader, String textFieldName, String classFieldName, Analyzer analyzer)` Train the classifier using the underlying Lucene index

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### KNearestNeighborClassifier

    public KNearestNeighborClassifier(int k)

  Create a `Classifier` using kNN algorithm

  Parameters:
    `k` - the number of neighbors to analyze as an `int`

Method Detail

### assignClass

    public ClassificationResult<BytesRef> assignClass(String text)
                                               throws IOException

  Assign a class (with score) to the given text String

  Specified by:
    `assignClass` in interface `Classifier<BytesRef>`
  Parameters:
    `text` - a String containing text to be classified
  Returns:
    a `ClassificationResult` holding assigned class of type `T` and score
  Throws:
    `IOException` - If there is a low-level I/O error.

### train

    public void train(AtomicReader atomicReader,
                      String textFieldName,
                      String classFieldName,
                      Analyzer analyzer)
               throws IOException

  Train the classifier using the underlying Lucene index

  Specified by:
    `train` in interface `Classifier<BytesRef>`
  Parameters:
    `atomicReader` - the reader to use to access the Lucene index
    `textFieldName` - the name of the field used to compare documents
    `classFieldName` - the name of the field containing the class assigned to documents
    `analyzer` - the analyzer used to tokenize / filter the unseen text
  Throws:
    `IOException` - If there is a low-level I/O error.

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