What Is Unsupervised Learning?

The one point that I want to emphasize here is that the adjective "unsupervised" does not mean that these algorithms run by themselves without human supervision. It simply indicates the absence of a desired or ideal output corresponding to each input. An analyst (or a data scientist) who is training an unsupervised learning model has to exercise a similar kind of modeling discipline as does the one who is training a supervised model. Alternatively, an analyst who is training an unsupervised learning model can exercise a similar amount of control on the resulting output by configuring model parameters as does the one who is training a supervised model. While supervised algorithms derive a mapping function from x to y so as to accurately estimate the y's corresponding to new x's, unsupervised algorithms employ predefined distance/similarity functions to map the distribution of input x's.