Introduction to RMarkdown
1 Don’t you want to improve your life? Let RMarkdown do the trick!
You may ask:
- How can I save time when I need to rerun my programs to update the results?
- How can I efficiently rewrite my report/homework if I need to change the data but keep all the analyses?
- How can I avoid dealing with the format of my report and focus on the content itself?
If these questions bother you at least once, then you need to learn “Markdown/RMarkdown”.
1.1 How to use R Markdown file in R-studio
The most recent version of R-studio has added the “R Markdown” file type as default. You can create an “R Markdown” file. 
The R Markdown file can generate three types of files as the report: HTML, pdf, and word. You can generate by clicking the “Knit” button as follows: 
If everything goes correct, you will have the HTML/pdf/word file generated and popped-up. PS: the pdf file generating process require LaTex (such as MikTex) installed.
1.2 Markdown Syntax: Simplest way of writing
headers - A single hashtag: first-level header. Two hashtags,
##, creates a second-level header, and so on.italicized and bold text - one asterisk, like this without realizing it. Two asterisks, like this, easy to use.
lists - Use asterisks or dash to create bullet points.
hyperlinks - create a hyperlink like this Data-Mining.
# Say Hello to **Data Mining** in Markdown
* [Data Mining in R on Github](https://xiaoruizhu.github.io/Data-Mining-R/)
* [Markdown Syntax](https://daringfireball.net/projects/markdown/basics)
* [StackOverflow](www.stackoverflow.com)
* [Reddit](www.reddit.com)
## R Markdown is a special type of Markdown in R1.3 How to communicate with codes? Use “knitr”
knitr is an R package that extends the markdown syntax. One of the most important functions of knitr is to include exectuable R code. Then, with the codes inside the paragraph, the technical report will be more readable than that not including codes. Besides, with knitr, the results of executed codes can be automatically included in the output report, which is a great feature. This feature makes your analyses “reproducible”. In this way, you can easily change your codes. Then, when you knit, the the results in your output report will be updated with your new codes.
Here’s some code
dim(iris)## [1] 150 5
Here’s a plot
More settings of the output of code chunks can be found rmarkdown and knitr websites.
1.4 Inline code
To include some calculation by R code in a line, one can surround the codes as follows:
Two plus two equals 4. (Use a pair of backticks and the letter r like this: ` r 2+2 `)