Package org.apache.lucene.classification.document

# Class SimpleNaiveBayesDocumentClassifier

java.lang.Object
org.apache.lucene.classification.SimpleNaiveBayesClassifier
org.apache.lucene.classification.document.SimpleNaiveBayesDocumentClassifier

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

public class SimpleNaiveBayesDocumentClassifier extends SimpleNaiveBayesClassifier implements DocumentClassifier<BytesRef>
A simplistic Lucene based NaiveBayes classifier, see `http://en.wikipedia.org/wiki/Naive_Bayes_classifier`

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`
`Analyzer` to be used for tokenizing document fields

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

`analyzer, classFieldName, indexReader, indexSearcher, query, textFieldNames`

## Constructor Summary

Constructors
Constructor
Description
`SimpleNaiveBayesDocumentClassifier(IndexReader indexReader, Query query, String classFieldName, Map<String,Analyzer> field2analyzer, String... textFieldNames)`
Creates a new NaiveBayes classifier.

## 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.
`protected String[]`
`getTokenArray(TokenStream tokenizedText)`
Returns a token array from the `TokenStream` in input

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

`assignClass, assignClassNormalizedList, countDocsWithClass, getClasses, getClasses, normClassificationResults, tokenize`

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

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

## Field Details

### field2analyzer

protected final Map<String,Analyzer> field2analyzer
`Analyzer` to be used for tokenizing document fields

## Constructor Details

### SimpleNaiveBayesDocumentClassifier

public SimpleNaiveBayesDocumentClassifier(IndexReader indexReader, Query query, String classFieldName, Map<String,Analyzer> field2analyzer, String... textFieldNames)
Creates a new NaiveBayes classifier.

Parameters:
  `indexReader` - the reader on the index to be used for classification
  `query` - a `Query` to eventually filter the docs used for training the classifier, or `null` if all the indexed docs should be used
  `classFieldName` - the name of the field used as the output for the classifier NOTE: must not be heavely analyzed as the returned class will be a token indexed for this field
  `textFieldNames` - the name of the fields used as the inputs for the classifier, they can contain boosting indication e.g. title^10

## 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.

### getTokenArray

protected String[] getTokenArray(TokenStream tokenizedText) throws IOException
Returns a token array from the `TokenStream` in input

Parameters:
  `tokenizedText` - the tokenized content of a field
Returns:
  a `String` array of the resulting tokens
Throws:
  `IOException` - If tokenization fails because there is a low-level I/O error