Data Mining: Practical Machine Learning Tools and Techniques, Second Edition

Now, finally, we can say what this book is about. It is about techniques for

finding and describing structural patterns in data. Most of the techniques that

we cover have developed within a field known as machine learning.But first let

us look at what structural patterns are.

Describing structural patterns

What is meant by structural patterns?How do you describe them? And what

form does the input take? We will answer these questions by way of illustration

rather than by attempting formal, and ultimately sterile, definitions. There will

be plenty of examples later in this chapter, but let’s examine one right now to

get a feeling for what we’re talking about.

Look at the contact lens data in Table 1.1. This gives the conditions under

which an optician might want to prescribe soft contact lenses, hard contact

lenses, or no contact lenses at all; we will say more about what the individual

6 CHAPTER 1| WHAT’S IT ALL ABOUT?

Table 1.1 The contact lens data.

Spectacle Tear production Recommended
Age prescription Astigmatism rate lenses

young myope no reduced none
young myope no normal soft
young myope yes reduced none
young myope yes normal hard
young hypermetrope no reduced none
young hypermetrope no normal soft
young hypermetrope yes reduced none
young hypermetrope yes normal hard
pre-presbyopic myope no reduced none
pre-presbyopic myope no normal soft
pre-presbyopic myope yes reduced none
pre-presbyopic myope yes normal hard
pre-presbyopic hypermetrope no reduced none
pre-presbyopic hypermetrope no normal soft
pre-presbyopic hypermetrope yes reduced none
pre-presbyopic hypermetrope yes normal none
presbyopic myope no reduced none
presbyopic myope no normal none
presbyopic myope yes reduced none
presbyopic myope yes normal hard
presbyopic hypermetrope no reduced none
presbyopic hypermetrope no normal soft
presbyopic hypermetrope yes reduced none
presbyopic hypermetrope yes normal none