Package org.apache.lucene.classification

# Class BooleanPerceptronClassifier

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

All Implemented Interfaces:
  `Classifier<Boolean>`

public class BooleanPerceptronClassifier extends Object implements Classifier<Boolean>
A perceptron (see `http://en.wikipedia.org/wiki/Perceptron`) based `Boolean` `Classifier`. The weights are calculated using `TermsEnum.totalTermFreq()` both on a per field and a per document basis and then a corresponding `FST` is used for class assignment.

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

## Constructor Summary

Constructors
Constructor
Description
`BooleanPerceptronClassifier(IndexReader indexReader, Analyzer analyzer, Query query, Integer batchSize, Double bias, String classFieldName, String textFieldName)`
Creates a `BooleanPerceptronClassifier`

## Method Summary

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

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

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

## Constructor Details

### BooleanPerceptronClassifier

public BooleanPerceptronClassifier(IndexReader indexReader, Analyzer analyzer, Query query, Integer batchSize, Double bias, String classFieldName, String textFieldName) throws IOException
Creates a `BooleanPerceptronClassifier`

Parameters:
  `indexReader` - the reader on the index to be used for classification
  `analyzer` - an `Analyzer` used to analyze unseen text
  `query` - a `Query` to eventually filter the docs used for training the classifier, or `null` if all the indexed docs should be used
  `batchSize` - the size of the batch of docs to use for updating the perceptron weights
  `bias` - the bias used for class separation
  `classFieldName` - the name of the field used as the output for the classifier
  `textFieldName` - the name of the field used as input for the classifier
Throws:
  `IOException` - if the building of the underlying `FST` fails and / or `TermsEnum` for the text field cannot be found

## Method Details

### assignClass

public ClassificationResult<Boolean> assignClass(String text) throws IOException
Description copied from interface: `Classifier`
Assign a class (with score) to the given text String

Specified by:
  `assignClass` in interface `Classifier<Boolean>`
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.

### getClasses

public List<ClassificationResult<Boolean>> getClasses(String text)
Description copied from interface: `Classifier`
Get all the classes (sorted by score, descending) assigned to the given text String.

Specified by:
  `getClasses` in interface `Classifier<Boolean>`
Parameters:
  `text` - a String containing text to be classified
Returns:
  the whole list of `ClassificationResult`, the classes and scores. Returns `null` if the classifier can't make lists.

### getClasses

public List<ClassificationResult<Boolean>> getClasses(String text, int max)
Description copied from interface: `Classifier`
Get the first `max` classes (sorted by score, descending) assigned to the given text String.

Specified by:
  `getClasses` in interface `Classifier<Boolean>`
Parameters:
  `text` - a String containing text to be classified
  `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.