Unsupervised learning

While supervised learning has made great advances over the last few years, most of this book will focus on working with labeled examples. However, sometimes we may not have labels. In this case, we can still use machine learning to find hidden patterns in data.

Clustering is a common form of unsupervised learning

Imagine a company that has a number of customers for its products. These customers can probably be grouped into different market segments, but what we don't know is what the different market segments are. We also cannot ask customers which market segment they belong to because they probably don't know. Which market segment of the shampoo market are you? Do you even know how shampoo firms segment their customers?

In this example, we would like an algorithm that looks at a lot of data from customers and groups them into segments. This is an example of unsupervised learning.

This area of machine learning is far less developed than supervised learning, but it still holds great potential.