说明：  R 是一种编程语言，也是用于数据分析和统计的软件环境。它是一个GNU 项目，这意味着它是自由的开源软件。它正在以指数级的速度不断成长——普遍认为，它的用户人数可能超过了100 万，它有4000 多个由开发社区贡献的附件包，而且每年以约25% 的速度增加。在本书创作之时，它在Tiobe 编程社区指数（Tiobe Programming Community Index）的开发语言流行榜上已排至第24 位，大致与SAS 和MATLAB 看齐。
(R is a programming language and a software environment for data analysis and statistics. It's a GNU Project, which means it's free open source software. It's growing exponentially - it's thought to have more than a million users, more than 4000 add ons contributed by the development community, and it's growing at about 25% a year. At the time of writing, it ranked 24th on the development language pop list of the tiobe programming community index, roughly in line with SAS and MATLAB)