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Orange.classification.majority.rst

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.. py:currentmodule:: Orange.classification.majority

Majority (majority)

.. index:: majority classifier
   pair: classification; majority classifier

Accuracy of classifiers is often compared with the "default accuracy", that is, the accuracy of a classifier which classifies all instances to the majority class. The training of such classifier consists of computing the class distribution and its modus. The model is represented as an instance of :obj:`Orange.classification.ConstantClassifier`.

MajorityLearner has two components, which are seldom used.

.. attribute:: estimator_constructor

    An estimator constructor that can be used for estimation of
    class probabilities. If left ``None``, probability of each class is
    estimated as the relative frequency of instances belonging to
    this class.


.. attribute:: apriori_distribution

    Apriori class distribution that is passed to estimator
    constructor if one is given.

Example

This "learning algorithm" will most often be used as a baseline, that is, to determine if some other learning algorithm provides any information about the class (:download:`majority-classification.py <code/majority-classification.py>`):

.. literalinclude:: code/majority-classification.py
    :lines: 7-