Most Popular Distance Metrics Used in KNN and When to Use Them - KDnuggets

KNN is the most commonly used and one of the simplest algorithms for finding patterns in classification and regression problems. It is an unsupervised algorithm and also known as lazy learning algorithm. It works by calculating the distance of 1 test observation from all the observation of the training dataset and then finding K nearest neighbors of it. This happens for each and every test observation and that is how it finds similarities in the data. For calculating distances KNN uses a distance metric from the list of available metrics.