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.