In this section, I learned to use many kinds of tools and methods to evaluate a fitted model, and sometimes use this method to improve the model. R has provides so many packages for us. It requires much more practise to be proficient.

This is a practice. I am still learning.

《机器学习与R语言实战》中的案例，分别展示了两种分类树的构建、可视化和评估。