Building Machine Learning Systems with Python - Third Edition

Building our first classification model

If the goal is to separate the three types of flowers, we can immediately make a few suggestions just by looking at the data. For example, petal length seems to be able to separate Iris Setosa from the other two flower species on its own.

Intuitively, we can build a simple model in our heads: if the petal width is smaller than about 1, then this is an Iris Setosa flower; otherwise it is either Iris Virginica or Iris Versicolor. Machine learning is when we write code to look for this type of separation automatically.

The problem of recognizing Iris Setosa apart from the other two species was very easy. However, we cannot immediately identify the best cut for distinguishing Iris Virginica from Iris Versicolor. ...