#### Code

##### demo

To get a sense of what R can do graphically, enter demo()at the command prompt. A sample of the graphs produced is included in figure 1.5. Other demonstrations include demo(Hershey), demo(persp), and demo(image). To see a complete list of demonstrations, enter demo() without parameters.

demo直接给出简洁的代码示例来解释如何使用相关的功能，可以说是十分有帮助的。这里拓展一下：

• [ ] demo()

• [ ] demo(package = .packages(all.available = TRUE))

• [ ] demo(“zoo-overplot”, package = “zoo”)

a character vector giving the packages to look into for demos, or NULL. By default, all packages in the search path are used. 这里，我们可以通过指定package的值来搜索指定包下的demo。如果不指定，则在所有已导入的包中搜索。

##### help functions

The vignettes returned by the vignette() function are practical introductory articles provided in PDF format. Not all packages have vignettes