K-nearest neighbors

K-nearest neighbors is a non-parametric machine learning model in which the model memorizes the training observation for classifying the unseen test data. It can also be called instance-based learning. This model is often termed as lazy learning, as it does not learn anything during the training phase like regression, random forest, and so on. Instead it starts working only during the testing/evaluation phase to compare the given test observations with nearest training observations, which will take significant time in comparing each test data point. Hence, this technique is not efficient on big data; also, performance does deteriorate when the number of variables is high due to the curse of dimensionality.

KNN voter example

KNN is explained better with the following short example. Objective is to predict the party for which voter will vote based on their neighborhood, precisely geolocation (latitude and longitude). Here we assume that we can identify the potential voter...