Classifiers Fujinaga
Bayes (optimal) Classifier (1) A priori probabilities: and Decision rule: given and decide if and probability of error Let be the feature(s). Let be the class (state)- conditional probability distribution function (pdf) for ; i.e., the pdf for given that the state of nature is
Bayes (optimal) Classifier (2) Assume we know and and also we discover the value of Using Bayes Rule: Decide if (Maximum likelihood)
Bayes (optimal) Classifier (3) A posteriori for a two class decision problem. The red region on the x axes depicts values for x for which you would decide ‘apple’ and the orange region is for ‘orange’. At every x, the posteriors must sum to 1.
Fisher’s Linear Discriminant If Petal Width < 3.272 - 0.3252xPetal Length, then Versicolor If Petal Width > 3.272 - 0.3252xPetal Length, then Verginica
Decision Tree If Petal Length < 2.65, then Setosa If Petal Length > 4.95, then Verginica If 2.65 < Petal Length < 4.95 then if Petal Width < 1.65 then Versicolor if Petal Width > 1.65 then Virginica