I've read in several papers that K-nearest neighbor can be supervised or unsupervised learning. Is Knn always unsupervised when one use it for clustering and supervised when one used it for classification? I've to know if there is a unsupervised Knn in classification as well.
Thanks in advance!
Phil
Best Answer
Assuming K is given, strictly speaking, KNN does not have any learning involved, i.e., there are no parameters we can tune to make the performance better. Or we are not trying to optimize an objective function from the training data set. This is a major differences from most supervised learning algorithms.
It is a rule that can be used in production time that can classify or clustering a instance based on its neighbors. Compute neighbors does not require label but label can be used to make the decision for the classification.