Machine Learning with Swift

Reasoning in high-dimensional spaces

Working with feature spaces of high dimensions requires special mental precautions, since our intuition used to deal with three-dimensional space starts to fail. For example, let's look at one peculiar property of n-dimensional spaces, known as an n-ball volume problem. N-ball is just a ball in n-dimensional Euclidean space. If we plot the volume of such n-ball (y axis) as a function of a number of dimensions (x axis), we'll see the following graph:

Figure 3.9: Volume of n-ball in n-dimensional space

Note that at the beginning the volume rises, until it reaches its peak in five-dimensional space, and then ...