weka.classifiers.bayes

## Class NaiveBayesMultinomial

- java.lang.Object
- - weka.classifiers.AbstractClassifier
  - - weka.classifiers.bayes.NaiveBayesMultinomial

- All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable, Classifier, CapabilitiesHandler, CapabilitiesIgnorer, OptionHandler, RevisionHandler, TechnicalInformationHandler, WeightedInstancesHandler
  Direct Known Subclasses:
    NaiveBayesMultinomialUpdateable

      public class NaiveBayesMultinomial
      extends AbstractClassifier
      implements WeightedInstancesHandler, TechnicalInformationHandler

  Class for building and using a multinomial Naive Bayes classifier. For more information see,
  Andrew Mccallum, Kamal Nigam: A Comparison of Event Models for Naive Bayes Text Classification. In: AAAI-98 Workshop on 'Learning for Text Categorization', 1998.
  The core equation for this classifier:
  P[Ci|D] = (P[D|Ci] x P[Ci]) / P[D] (Bayes rule)
  where Ci is class i and D is a document.

  BibTeX:

       @inproceedings{Mccallum1998,
          author = {Andrew Mccallum and Kamal Nigam},
          booktitle = {AAAI-98 Workshop on 'Learning for Text Categorization'},
          title = {A Comparison of Event Models for Naive Bayes Text Classification},
          year = {1998}
       }

  Valid options are:

       -D
        If set, classifier is run in debug mode and
        may output additional info to the console

  Version:
    $Revision: 11301 $
  Author:
    Andrew Golightly (acg4@cs.waikato.ac.nz), Bernhard Pfahringer (bernhard@cs.waikato.ac.nz)
  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `NaiveBayesMultinomial()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `buildClassifier(Instances instances)` Generates the classifier.
    `double[]` | `distributionForInstance(Instance instance)` Calculates the class membership probabilities for the given test instance.
    `Capabilities` | `getCapabilities()` Returns default capabilities of the classifier.
    `java.lang.String` | `getRevision()` Returns the revision string.
    `TechnicalInformation` | `getTechnicalInformation()` Returns an instance of a TechnicalInformation object, containing detailed information about the technical background of this class, e.g., paper reference or book this class is based on.
    `java.lang.String` | `globalInfo()` Returns a string describing this classifier
    `double` | `lnFactorial(int n)` Fast computation of ln(n!) for non-negative ints negative ints are passed on to the general gamma-function based version in weka.core.SpecialFunctions if the current n value is higher than any previous one, the cache is extended and filled to cover it the common case is reduced to a simple array lookup
    `static void` | `main(java.lang.String[] argv)` Main method for testing this class.
    `java.lang.String` | `toString()` Returns a string representation of the classifier.

    - ### Methods inherited from class weka.classifiers.AbstractClassifier

      `classifyInstance, debugTipText, doNotCheckCapabilitiesTipText, forName, getDebug, getDoNotCheckCapabilities, getOptions, listOptions, makeCopies, makeCopy, runClassifier, setDebug, setDoNotCheckCapabilities, setOptions`

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

      `equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### NaiveBayesMultinomial

          public NaiveBayesMultinomial()

  - ### Method Detail

    - #### globalInfo

          public java.lang.String globalInfo()

      Returns a string describing this classifier
      Returns:
        a description of the classifier suitable for displaying in the explorer/experimenter gui

    - #### getTechnicalInformation

          public TechnicalInformation getTechnicalInformation()

      Returns an instance of a TechnicalInformation object, containing detailed information about the technical background of this class, e.g., paper reference or book this class is based on.
      Specified by:
        `getTechnicalInformation` in interface `TechnicalInformationHandler`
      Returns:
        the technical information about this class

    - #### getCapabilities

          public Capabilities getCapabilities()

      Returns default capabilities of the classifier.
      Specified by:
        `getCapabilities` in interface `Classifier`
      Specified by:
        `getCapabilities` in interface `CapabilitiesHandler`
      Overrides:
        `getCapabilities` in class `AbstractClassifier`
      Returns:
        the capabilities of this classifier
      See Also:
        `Capabilities`

    - #### buildClassifier

          public void buildClassifier(Instances instances)
                               throws java.lang.Exception

      Generates the classifier.
      Specified by:
        `buildClassifier` in interface `Classifier`
      Parameters:
        `instances` - set of instances serving as training data
      Throws:
        `java.lang.Exception` - if the classifier has not been generated successfully

    - #### distributionForInstance

          public double[] distributionForInstance(Instance instance)
                                           throws java.lang.Exception

      Calculates the class membership probabilities for the given test instance.
      Specified by:
        `distributionForInstance` in interface `Classifier`
      Overrides:
        `distributionForInstance` in class `AbstractClassifier`
      Parameters:
        `instance` - the instance to be classified
      Returns:
        predicted class probability distribution
      Throws:
        `java.lang.Exception` - if there is a problem generating the prediction

    - #### lnFactorial

          public double lnFactorial(int n)

      Fast computation of ln(n!) for non-negative ints negative ints are passed on to the general gamma-function based version in weka.core.SpecialFunctions if the current n value is higher than any previous one, the cache is extended and filled to cover it the common case is reduced to a simple array lookup
      Parameters:
        `n` - the integer
      Returns:
        ln(n!)

    - #### toString

          public java.lang.String toString()

      Returns a string representation of the classifier.
      Overrides:
        `toString` in class `java.lang.Object`
      Returns:
        a string representation of the classifier

    - #### getRevision

          public java.lang.String getRevision()

      Returns the revision string.
      Specified by:
        `getRevision` in interface `RevisionHandler`
      Overrides:
        `getRevision` in class `AbstractClassifier`
      Returns:
        the revision

    - #### main

          public static void main(java.lang.String[] argv)

      Main method for testing this class.
      Parameters:
        `argv` - the options