R Markdown

R Markdown is a useful tool for creating documents, reports, presentations, dashboards and even websites. In this chapter, we will cover basics of R Markdown for creating documents including your R codes and results. After reading this chapter, the readers will be able to:

  • write R codes and show the results in a R Markdown file.

  • knit a R Markdown script into a pdf file.

2.4 Basics of R Markdown

2.4.1 Creating a new R Markdown file

To crate a new R Markdown file, click on the New File icon and select R Marmdown....

Let’s select PDF in the Default Output Format: section and click OK.

On the top shows the title, author, date, and the output format. When we knit this R Markdown file, it will create a pdf document.

2.4.2 Knitting a document

In order to knit an R Markdown file, just click on the knit icon . Or use the keyboard short cut, Shift + Ctrl + K. Then the R Studio will create a pdf/html file and save it under the current working directory.

2.4.3 Writing code chunks

Inside a code chunk goes the R codes you want to run and show in your document. You can create a code chunk by Code -> Insert Chucnk, or the keyboard short cut, Ctrl + Alt + I. Below is an example of a code chunk.

In order to run the R codes inside a code chunk, click on the top right side of your code chunk.

Inside the braces tells us that this is an R code chunk, and the name of this chunk is chunkname. Naming your code chunk helps you keep track of which part of your R Markdown file yields error when knitting it.

The echo=FASLE option prevents the code from appearing in your document, but not the results. This option is useful when embedding a figure. If you set echo=TRUE, the code will appear in the knitted document.

2.4.4 Structure of a document

# signs indicate headers. You can use up to 6-level headers by increasing the number of #.

# Header 1
## Header 2
### Header 3

Outside the code chunks, you can write plain text explaining the R codes and results.

In order to list an unordered list, put * in front of the list.

  • Item 1
  • Item 2

You can create an ordered list by writing 1., 2., and so on.

  1. Item 1
  2. Item 2