What is k-NN?

k-Nearest Neighbors (k-NN) is a simple, non-parametric algorithm used for both classification and regression. In k-NN classification, an object is classified by a majority vote of its neighbors, with the object being assigned to the class most common among its k nearest neighbors (k is a positive integer, typically small). In k-NN regression, the output is the average (or weighted average) of the values of its k nearest neighbors. k-NN is widely used in pattern recognition, data mining, and intrusion detection.