Package org.apache.lucene.classification

Class BM25NBClassifier

java.lang.Object
org.apache.lucene.classification.BM25NBClassifier
All Implemented Interfaces:
Classifier<org.apache.lucene.util.BytesRef>
public class BM25NBClassifier extends Object implements Classifier<org.apache.lucene.util.BytesRef>
A classifier approximating naive bayes classifier by using pure queries on BM25.
WARNING: This API is experimental and might change in incompatible ways in the next release.

  • Constructor Details

    • BM25NBClassifier

      public BM25NBClassifier(org.apache.lucene.index.IndexReader indexReader, org.apache.lucene.analysis.Analyzer analyzer, org.apache.lucene.search.Query query, String classFieldName, String... textFieldNames)
      Creates a new NaiveBayes classifier.
      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
      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, NO boosting supported per field

  • Method Details

    • assignClass

      public ClassificationResult<org.apache.lucene.util.BytesRef> assignClass(String inputDocument) throws IOException
      Description copied from interface: Classifier
      Assign a class (with score) to the given text String
      Specified by:
      assignClass in interface Classifier<org.apache.lucene.util.BytesRef>
      Parameters:
      inputDocument - 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<org.apache.lucene.util.BytesRef>> getClasses(String text) throws IOException
      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<org.apache.lucene.util.BytesRef>
      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.
      Throws:
      IOException - If there is a low-level I/O error.

    • getClasses

      public List<ClassificationResult<org.apache.lucene.util.BytesRef>> getClasses(String text, int max) throws IOException
      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<org.apache.lucene.util.BytesRef>
      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.
      Throws:
      IOException - If there is a low-level I/O error.