swirl包——R语言自学神器+期末救星

马上就要期末考试了，学了一学期的R语言，但感觉相关的知识点非常的繁琐，复习起来光看代码和课堂笔记也很困，所以一直在想有没有相关的平台可以进行操练。

最后找到了一个R语言的包，叫swirl，它是JHU开发出来的一个交互式R语言自学包，听上去很高级，自己练习了一天以后感觉非常不错，很基础，适合初学者上手，而且学习起来一点也不困，因为一直在思考+敲键盘。不过也需要你英语水平过关，因为是全英文的互动界面：

那么怎么开始呢，你只需要先清空工作台：

rm(list = ls())

然后在RStudio里面进行包的安装，根据指令就可以进行开始自学啦：

> install.packages("swirl")
> library(swirl)
| Hi! Type swirl() when you are ready to begin.

> swirl()
'''
| Welcome to swirl! Please sign in. If you've been here before, use the same name
| as you did then. If you are new, call yourself something unique.
'''
What shall I call you? Lucas
'''
| Thanks, Lucas. Let's cover a couple of quick housekeeping items before we begin
| our first lesson. First of all, you should know that when you see '...', that
| means you should press Enter when you are done reading and ready to continue.
'''
...  <-- That's your cue to press Enter to continue
'''
| Also, when you see 'ANSWER:', the R prompt (>), or when you are asked to select
| from a list, that means it's your turn to enter a response, then press Enter to
| continue.
'''
Select 1, 2, or 3 and press Enter 

1: Continue.
2: Proceed.
3: Let's get going!

Selection: 1
'''
| You can exit swirl and return to the R prompt (>) at any time by pressing the Esc
| key. If you are already at the prompt, type bye() to exit and save your progress.
| When you exit properly, you'll see a short message letting you know you've done
| so.

| When you are at the R prompt (>):
| -- Typing skip() allows you to skip the current question.
| -- Typing play() lets you experiment with R on your own; swirl will ignore what
| you do...
| -- UNTIL you type nxt() which will regain swirl's attention.
| -- Typing bye() causes swirl to exit. Your progress will be saved.
| -- Typing main() returns you to swirl's main menu.
| -- Typing info() displays these options again.

| Let's get started!
'''

开场白结束以后，它会提供5个大的课程，每个课程里面对应多个章节，每个章节为一个小课，因此不要以为学完该章节就把整个学完了， That’s not even close!

| To begin, you must install a course. I can install a course for you from the
| internet, or I can send you to a web page
| (https://github.com/swirldev/swirl_courses) which will provide course options and
| directions for installing courses yourself. (If you are not connected to the
| internet, type 0 to exit.)

1: R Programming: The basics of programming in R
2: Regression Models: The basics of regression modeling in R
3: Statistical Inference: The basics of statistical inference in R
4: Exploratory Data Analysis: The basics of exploring data in R
5: Don't install anything for me. I'll do it myself.

Selection: 1
  |==========================================================================| 100%

| Course installed successfully!


| Please choose a course, or type 0 to exit swirl.

1: R Programming
2: Take me to the swirl course repository!

Selection: 1

先选择大课，然后选择小课?

| Please choose a lesson, or type 0 to return to course menu.

 1: Basic Building Blocks      2: Workspace and Files     
 3: Sequences of Numbers       4: Vectors                 
 5: Missing Values             6: Subsetting Vectors      
 7: Matrices and Data Frames   8: Logic                   
 9: Functions                 10: lapply and sapply       
11: vapply and tapply         12: Looking at Data         
13: Simulation                14: Dates and Times         
15: Base Graphics             

Selection: 7
|                                                                          |   0%

| In this lesson, we'll cover matrices and data frames. Both represent
| 'rectangular' data types, meaning that they are used to store tabular data, with
| rows and columns.

开始快乐学习吧！