Train a classifier on an unbalanced training set:

Obtain class probabilities for a new example:

Set a uniform prior distribution for the classes:

Set the prior distribution of classes inside the classifier:

Priors of unspecified classes are functions of the remaining probability mass:

Restrict the built-in language classifier to only two languages:

Train a classifier to recognize if an organism is diseased on a balanced training set:

Find the probability that a new organism is diseased:

Find the probability that the same organism is diseased, incorporating prior knowledge that diseased organisms represent only 1% of the population:

Train a classifier able to predict if a website user will buy a given item based on his behavior:

Define and visualize a model for the probability of buying the item as a function of the outside temperature:

Use this model and WeatherData to increase the prediction performance for a Parisian user, without additional training: