R语言作图教科书 This book is here to help you get your job done. In general, you may use the code in this
book in your programs and documentation. You do not need to contact us for permission
unless you’re reproducing a significant portion of the code. For example, writing a
program that uses several chunks of code from this book does not require permission.
Selling or distributing a CD-ROM of examples from O’Reilly books does require permission.
Answering a question by citing this book and quoting example code does not
require permission. Incorporating a significant amount of example code from this book
into your product’s documentation does require permission.