June 2020
Beginner to intermediate
522 pages
9h 6m
Chinese
Content preview from R 语言经典实例（原书第 2 版）
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52
｜
第
2
章
优先级。
2.11.4 另请参阅
关于向量之间运算的细节，参阅 2.10 节；关于矩阵的运算，参阅 5.15 节；关于如何定
义所需要的运算符，参阅 12.17 节。可以查看 R 软件中算术运算与语法的帮助页面，也
可以参阅
R in a Nutshell
（
https://oreil.ly/2wUtwyf
）第 5 章和第 6 章的内容。
2.12 减少输入，得到更多命令
2.12.1 问题
你对于输入大量长长的命令，尤其是不断重复输入同一命令感到枯燥。
2.12.2 解决方案
打开一个编辑器窗口将经常使用的 R 代码存放其中，并直接从该窗口中执行这些命令。
在命令行仅仅输入一些简短的或者一次性的命令。
完成后，你可以把积累的命令存储为一个脚本文件，以便以后使用。
2.12.3 讨论
典型的 R 软件初学者会在控制台窗口中键入一个表达式，然后查看结果。当他有信心
后，就开始输入更加复杂的表达式，甚至开始输入多行表达式。很快，他一遍又一遍地
输入相同的多行命令（可能只有很小的变化），以便执行日益复杂的计算。
经验丰富的 R 用户通常不会重新键入复杂表达式。他们可能会输入相同的表达式一次或
两次，当他们意识到这些命令有用且可重复使用时，他们会将其剪切并粘贴到编辑器窗
口中。在以后需要使用部分命令时，他们会在编辑器窗口中选中这部分命令，并让 R 来
执行，而不是重新输入这些命令。这种技术特别强大，因为他们的代码片段有时候会演
变成很长的代码块。
在 RStudio 中，IDE 中的一些快捷方式可以促进这种工作方式 ...
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