# Today I Learned

Some of the things I've learned every day since Oct 10, 2016

## 76: Probabilistic Classifiers

As used in machine learning, the term probabilistic classifier refers to a function $f: X \rightarrow \pi _Y$, where $X$ is the set of objects to be classified, $Y$ is the set of classes, and $\pi _Y$ is the set of probability distributions over $Y$. That is, a probabilistic classifier takes an object to be classified and gives the probability of that object belonging to each of the possible classes.

This contrasts with a non-probabilistic classifier, which instead is simply a function $g: X \rightarrow Y$ that assigns a single class given an object. Often, the choice is simply that category with the highest probability.