
Ubiquitous Data Mining 195
Figure 12.2: Example of a 2-sensor network. Although the number of cells to
monitor increases exponentially with the number of sensors (dimensions), and
unless data is uniformly distributed in all dimensions (extremely unlikely in
usual data) the data occupy much fewer cells. Left plot presents an equal-width
discretization, while right plot presents an equal-frequency discretization.
cess of updating the first layer works online, doing a single scan over the data
stream, hence being able to process infinite sequences of data, processing each
example in constant time and (almost) constant space. The update process of
the second ...