August 2018
Intermediate to advanced
227 pages
4h 16m
Chinese
Content preview from 高效R语言编程
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34
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第
2
章
下面代码将创建用户专用的
.Renviron
文件（文件将保存
API
密钥及交叉工程
环境变量），而不是改写任何已存在的文件。
user_renviron = path.expand
（
file.path
（
"~", ".Renviron"
））
file.edit
（
user_renviron
）
#
如该代码执行失败，使用其他文本编辑器打开
借助
pathological
包的 os_path() 函数，可以查找
.Rprofile
与
.Renviron
文
件在你系统中的位置，读读 example(Startup) 的输出也会很受益的。
下一节将给出位置、内容，以及各自用法的更详细解释。
.Rprofile
文件
默认情况下，
R
以特定的顺序查找
/
运行上述三个目录下的
.Rprofile
文
件。
.Rprofile
文件是每次
R
启动时均执行的简单的脚本文件。可在 R_HOME、
HOME 及项目
home
目录（可用 getwd() 命令查看）下找到它们。查看是否存
在所有用户启动
R
时都需运行的
.Rprofile
文件，代码如下
:
site_path = R.home(component = "home")
fname = file.path(site_path, "etc", "Rprofile.site")
file.exists(fname)
上述代码检查
Rprofile.site
是否存在 R_HOME 目录中。前面已介绍过你的
home
目录下的
.Rprofile
是用户专用的。同样，我们可用下列代码测试这个文件是
否存在：
file.exists("~/.Rprofile") ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.