Introduction to {rmarkdown}

class: center, middle, inverse, title-slide

# Introduction to {rmarkdown}
## R-ladies Barcelona
### Sarah Bonnin
### 2019-12-12

---

## What is Markdown ?

* **Lightweight markup language**

* **Easy-to-read** and **easy-to-write** plain text format

* Rendered as **HTML** document through [Blackfriday](https://gohugo.io/getting-started/configuration/)

---

## What is R Markdown ?

* Advanced version of "plain" Markdown: **embeds** and **executes R code**

* **Simple formatting syntax** for authoring **HTML, PDF, and MS Word** documents.

* Easy to **report** and **share** analysis.

* **Reproducibility** and **transparency**.

* Produce **high quality documents**.

---

## Install and load

{rmarkdown} package is **open-source** and can be installed and loaded as follows:

```r
install.packages("rmarkdown")
```

```r
library(rmarkdown)
```

---

## R Markdown Cheatsheet

R Markdown [Cheatsheet](https://rstudio.com/wp-content/uploads/2016/03/rmarkdown-cheatsheet-2.0.pdf)

---

## R Markdown (RMD) file

* Plain text file

* **.Rmd** extension

* Create, write and run from **R Studio**

---

## How does it work?

* **{rmarkdown}** feeds the input **.Rmd** file to **{knitr}**

* **{knitr}** creates a new **.md** file containing the output

* The **.md** file is then fed to **pandoc** that creates the final output

---

## R Markdown file and rendering

Example of a **source file** and its **rendering**:

---

## Create an .Rmd file in R Studio

File -> New File -> R Markdown...

---

## Create an .Rmd file in R Studio

Choose output format:

---

## Template .Rmd file

---

## First knit!

Knit the template **.Rmd** file to HTML!

---

## First knit!

---

## Blocks

* Header (optional) in **YAML** format surrounded by **3 dashes**

* R code chunks surrounded by **3 back ticks**

* (Formatted) text

---

## Header

The YAML header is surrounded by 3 dashes (**---**)

```r
---
title: "TEST"
author: "Sarah Bonnin"
date: "12/8/2019"
output: html_document
---
```

Add a table of content:

```r
---
title: "TEST"
author: "Sarah Bonnin"
date: "12/8/2019"
output: 
  html_document:
    toc: true
---
```

---

## Format text

```r
 *Italic* / _Italic_
 **Bold** / __Bold__
 ***Bold + Italic*** / ___Bold + Italic___
 superscript^2^   
 ~~strikethrough~~  
```

*Italic* / _Italic_

**Bold** / __Bold__

***Bold + Italic*** / ___Bold + Italic___

Superscript^2^   
 
~~Strikethrough~~

---

## Format text
### Headers

````r
# Header 1
## Header 2
### Header 3
#### Header 4
````

# Header 1
## Header 2
### Header 3
#### Header 4

---

## Format text
### Headers

* Headers will be automatically organized in the **table of content** !

````r
# Section 1
## Subsection 1.1

Some text

## Subsection 1.2

More text

# Section 2

## Subsection 2.1

Text from section 2.1

## Subsection 2.2

Text from section 2.2
````

---

## Format text
### Headers

---

## Lists

### unordered

````
 * first item
 * second item
   * first sub-item
   * second sub-item
````

* first item
* second item
  * first sub-item
  * second sub-item

---

## Lists

### ordered

````r
 1. first ordered item
 2. second ordered item
   + first sub-item
   + second sub-item
````
    
--

1. first ordered item
2. second ordered item
  + first sub-item
  + second sub-item

---

## Code blocks
### Options

Customize the rendering with **options**:

---

## Code blocks
### Load packages in the background

* **.Rmd** files are "independent": packages you will need in your code should be loaded **in a code block inside the document** !

* If you want to show **no output** and **no message** but still **execute the code**, use the option **include = FALSE**

* Load the packages you will need to run the code of your analysis, **at the beginning of the .Rmd file**:

````r
```{r, include = FALSE}
library(ggplot2)
library(dplyr)
library(kableExtra)
```
````

---

## Code blocks: examples

The following code:

````r
```{r, eval=TRUE, echo=TRUE, message=TRUE}
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```
````

Renders as:

```r
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```

```
## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
```

![](191212_rladies_rmarkdown_files/figure-html/unnamed-chunk-19-1.png)

---

## Code blocks: examples

The following code:

````r
```{r, eval=TRUE, echo=TRUE, message=TRUE, fig.height=3}
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```
````

Renders as:

```r
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```

```
## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
```

![](191212_rladies_rmarkdown_files/figure-html/unnamed-chunk-20-1.png)

---

## Code blocks: examples

The following code:

````r
```{r, eval=TRUE, echo=TRUE, message=FALSE, fig.height=3}
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```
````

Renders as:

```r
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```

![](191212_rladies_rmarkdown_files/figure-html/unnamed-chunk-21-1.png)

---

## Code blocks: examples

The following code:

````r
```{r, eval=TRUE, echo=FALSE, message=FALSE, fig.height=3}
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```
````

Renders as:

![](191212_rladies_rmarkdown_files/figure-html/unnamed-chunk-22-1.png)

---

## Code blocks: examples

The following code:

````r
```{r, eval=FALSE, echo=TRUE, message=FALSE, fig.height=3}
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```
````

Renders as:

```r
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```

---

## Code blocks: examples

The following code:

````r
```{r, eval=FALSE, echo=FALSE, message=FALSE, fig.height=3}
 ggplot(data=cars, aes(x=speed)) + geom_histogram()
```
````

Renders as:

NOTHING! No code, no output, no message...

---

## Code blocks: examples (tidy)

The following code:

````r
```{r, eval=FALSE, echo=TRUE, message=FALSE, fig.height=3, tidy=TRUE}
 ggplot(data=cars,aes(x=speed))+geom_histogram()
```
````

Renders as:

```r
ggplot(data = cars, aes(x = speed)) + geom_histogram()
```

---

## Code blocks

Include options globally:

````r
```{r setup, include=FALSE}
 knitr::opts_chunk$set(echo = TRUE, tidy = TRUE, message = FALSE)
```
````

---

## Code blocks: Python and bash

{rmarkdown} can also execute, for example, **bash** and **Python** blocks of code.

````bash
```{bash}
ls *
```
````

```bash
ls *
```

```
## 191212_rladies_rmarkdown.html
## 191212_rladies_rmarkdown.Rmd
## index.html
## README.md
## 
## 191212_rladies_rmarkdown_files:
## figure-html
## 
## images:
## RMD_choose_output.png
## RMD_create.png
## RMD_knit.png
## RMD_knit_template_output.png
## RMD_knit_template.png
## RMD_options.png
## RMD_template.png
## RMD_TOC_output.png
## 
## libs:
## kePrint-0.0.1
## remark-css-0.0.1
```

---

## Code blocks: Python and bash

{rmarkdown} can also execute, for example, **bash** and **Python** blocks of code.

````python
```{python}
x = 'Rladies Barcelona'
print(x.split(' '))
```
````

```python
x = 'Rladies Barcelona'
print(x.split(' '))
```

```
## ['Rladies', 'Barcelona']
```

---

## Code blocks: knitr language engines

{rmarkdown} can execute **many different languages!**

See this [knitr language engines guide](https://bookdown.org/yihui/rmarkdown/language-engines.html)

---

## Insert images

Recommended / easier to format way with **knitr::include_graphics**:

````r
```{r}
knitr::include_graphics("https://rladies.org/wp-content/uploads/2016/12/R-LadiesGlobal.png")
```
````

```r
knitr::include_graphics("https://rladies.org/wp-content/uploads/2016/12/R-LadiesGlobal.png")
```

![](https://rladies.org/wp-content/uploads/2016/12/R-LadiesGlobal.png)

---

## Insert images

Recommended / easier to format way with **knitr::include_graphics**:

````r
```{r, out.width="50%", echo=FALSE, fig.align="center"}
knitr::include_graphics("https://rladies.org/wp-content/uploads/2016/12/R-LadiesGlobal.png")
```
````

---

## Links

You can **link** web pages:
--

````r
Here is a [link]("https://rmarkdown.rstudio.com/") 
to {rmarkdown} page on [R Studio](https://rstudio.com/) website.
````

Here is a [link]("https://rmarkdown.rstudio.com/") 
to {rmarkdown} page on [R Studio](https://rstudio.com/) website.

---

## Create tables

You can create tables:

````r
Date  | Workshop
----- | -----
12/12/2019 | R Markdown
21/01/2020 | Forecasting
````

Date  | Workshop
----- | -----
12/12/2019  | R Markdown
21/01/2020  | Forecasting

---

## Show R objects as tables

Format tables with **knitr::kable** and [**{kableExtra}**](http://haozhu233.github.io/kableExtra/awesome_table_in_html.html) package.

````r
```{r}
knitr::kable(head(iris))
```
````

---

## Show R objects as tables

**Bold** columns

````r
```{r}
knitr::kable(head(iris)) %>%
  column_spec(1:2, bold = TRUE)
```
````

<table>
 <thead>
  <tr>
   <th style="text-align:right;"> Sepal.Length </th>
   <th style="text-align:right;"> Sepal.Width </th>
   <th style="text-align:right;"> Petal.Length </th>
   <th style="text-align:right;"> Petal.Width </th>
   <th style="text-align:left;"> Species </th>
  </tr>
 </thead>
<tbody>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 5.1 </td>
   <td style="text-align:right;font-weight: bold;"> 3.5 </td>
   <td style="text-align:right;"> 1.4 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 4.9 </td>
   <td style="text-align:right;font-weight: bold;"> 3.0 </td>
   <td style="text-align:right;"> 1.4 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 4.7 </td>
   <td style="text-align:right;font-weight: bold;"> 3.2 </td>
   <td style="text-align:right;"> 1.3 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 4.6 </td>
   <td style="text-align:right;font-weight: bold;"> 3.1 </td>
   <td style="text-align:right;"> 1.5 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 5.0 </td>
   <td style="text-align:right;font-weight: bold;"> 3.6 </td>
   <td style="text-align:right;"> 1.4 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 5.4 </td>
   <td style="text-align:right;font-weight: bold;"> 3.9 </td>
   <td style="text-align:right;"> 1.7 </td>
   <td style="text-align:right;"> 0.4 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
</tbody>
</table>

---

## Show R objects as tables

**Colored** rows

````r
```{r}
knitr::kable(head(iris)) %>%
  row_spec(1:3, color = "white", background = "red")
```
````

<table>
 <thead>
  <tr>
   <th style="text-align:right;"> Sepal.Length </th>
   <th style="text-align:right;"> Sepal.Width </th>
   <th style="text-align:right;"> Petal.Length </th>
   <th style="text-align:right;"> Petal.Width </th>
   <th style="text-align:left;"> Species </th>
  </tr>
 </thead>
<tbody>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 5.1 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 3.5 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.4 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 4.9 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 3.0 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.4 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 4.7 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 3.2 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.3 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 4.6 </td>
   <td style="text-align:right;"> 3.1 </td>
   <td style="text-align:right;"> 1.5 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 5.0 </td>
   <td style="text-align:right;"> 3.6 </td>
   <td style="text-align:right;"> 1.4 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 5.4 </td>
   <td style="text-align:right;"> 3.9 </td>
   <td style="text-align:right;"> 1.7 </td>
   <td style="text-align:right;"> 0.4 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
</tbody>
</table>

---

## Show R objects as tables

Change **font size**

````r
```{r}
knitr::kable(head(iris)) %>%
  kable_styling(font_size = 10)
```
````

---

## Show R objects as tables

All together

````r
```{r}
knitr::kable(head(iris)) %>%
  kable_styling(font_size = 10) %>%
  row_spec(1:3, color = "white", background = "red") %>%
  column_spec(1:2, bold = TRUE)
```
````

<table class="table" style="font-size: 10px; margin-left: auto; margin-right: auto;">
 <thead>
  <tr>
   <th style="text-align:right;"> Sepal.Length </th>
   <th style="text-align:right;"> Sepal.Width </th>
   <th style="text-align:right;"> Petal.Length </th>
   <th style="text-align:right;"> Petal.Width </th>
   <th style="text-align:left;"> Species </th>
  </tr>
 </thead>
<tbody>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 5.1 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 3.5 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.4 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 4.9 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 3.0 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.4 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 4.7 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 3.2 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.3 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 4.6 </td>
   <td style="text-align:right;font-weight: bold;"> 3.1 </td>
   <td style="text-align:right;"> 1.5 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 5.0 </td>
   <td style="text-align:right;font-weight: bold;"> 3.6 </td>
   <td style="text-align:right;"> 1.4 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 5.4 </td>
   <td style="text-align:right;font-weight: bold;"> 3.9 </td>
   <td style="text-align:right;"> 1.7 </td>
   <td style="text-align:right;"> 0.4 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
</tbody>
</table>

---

## Show R objects as tables

Add extra headers

````r
```{r}
knitr::kable(head(iris)) %>%
  kable_styling(font_size = 10) %>%
  row_spec(1:3, color = "white", background = "red") %>%
  column_spec(1:2, bold = TRUE) %>%
  add_header_above(c("Sepal" = 2, "Petal" = 2, " " = 1))
```
````

<table class="table" style="font-size: 10px; margin-left: auto; margin-right: auto;">
 <thead>
<tr>
<th style="border-bottom:hidden; padding-bottom:0; padding-left:3px;padding-right:3px;text-align: center; " colspan="2"><div style="border-bottom: 1px solid #ddd; padding-bottom: 5px; ">Sepal</div></th>
<th style="border-bottom:hidden; padding-bottom:0; padding-left:3px;padding-right:3px;text-align: center; " colspan="2"><div style="border-bottom: 1px solid #ddd; padding-bottom: 5px; ">Petal</div></th>
<th style="border-bottom:hidden" colspan="1"></th>
</tr>
  <tr>
   <th style="text-align:right;"> Sepal.Length </th>
   <th style="text-align:right;"> Sepal.Width </th>
   <th style="text-align:right;"> Petal.Length </th>
   <th style="text-align:right;"> Petal.Width </th>
   <th style="text-align:left;"> Species </th>
  </tr>
 </thead>
<tbody>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 5.1 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 3.5 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.4 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 4.9 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 3.0 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.4 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 4.7 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;font-weight: bold;"> 3.2 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 1.3 </td>
   <td style="text-align:right;color: white !important;background-color: red !important;"> 0.2 </td>
   <td style="text-align:left;color: white !important;background-color: red !important;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 4.6 </td>
   <td style="text-align:right;font-weight: bold;"> 3.1 </td>
   <td style="text-align:right;"> 1.5 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 5.0 </td>
   <td style="text-align:right;font-weight: bold;"> 3.6 </td>
   <td style="text-align:right;"> 1.4 </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;font-weight: bold;"> 5.4 </td>
   <td style="text-align:right;font-weight: bold;"> 3.9 </td>
   <td style="text-align:right;"> 1.7 </td>
   <td style="text-align:right;"> 0.4 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
</tbody>
</table>

---

## Show R objects as tables

Conditional formatting

````r
```{r}
head(iris) %>%
mutate(
  Petal.Length = cell_spec(Petal.Length, "html", color = ifelse(Petal.Length > 1.4, "red", "blue"))
) %>%
kable(format="html", escape=FALSE) %>%
kable_styling("striped", full_width = F, font_size = 10)
```
````

<table class="table table-striped" style="font-size: 10px; width: auto !important; margin-left: auto; margin-right: auto;">
 <thead>
  <tr>
   <th style="text-align:right;"> Sepal.Length </th>
   <th style="text-align:right;"> Sepal.Width </th>
   <th style="text-align:left;"> Petal.Length </th>
   <th style="text-align:right;"> Petal.Width </th>
   <th style="text-align:left;"> Species </th>
  </tr>
 </thead>
<tbody>
  <tr>
   <td style="text-align:right;"> 5.1 </td>
   <td style="text-align:right;"> 3.5 </td>
   <td style="text-align:left;"> <span style="     color: blue !important;">1.4</span> </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 4.9 </td>
   <td style="text-align:right;"> 3.0 </td>
   <td style="text-align:left;"> <span style="     color: blue !important;">1.4</span> </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 4.7 </td>
   <td style="text-align:right;"> 3.2 </td>
   <td style="text-align:left;"> <span style="     color: blue !important;">1.3</span> </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 4.6 </td>
   <td style="text-align:right;"> 3.1 </td>
   <td style="text-align:left;"> <span style="     color: red !important;">1.5</span> </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 5.0 </td>
   <td style="text-align:right;"> 3.6 </td>
   <td style="text-align:left;"> <span style="     color: blue !important;">1.4</span> </td>
   <td style="text-align:right;"> 0.2 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
  <tr>
   <td style="text-align:right;"> 5.4 </td>
   <td style="text-align:right;"> 3.9 </td>
   <td style="text-align:left;"> <span style="     color: red !important;">1.7</span> </td>
   <td style="text-align:right;"> 0.4 </td>
   <td style="text-align:left;"> setosa </td>
  </tr>
</tbody>
</table>

---

## Hands on !

Modify the **.Rmd template**:

* Modify global options so blocks of code are always **tidy**.

* **plot(pressure)**: show code but hide plot.

* Format **summary(cars)** with **kable** and **{kableExtra}**: highlight in yellow the "Median" row.

* Add the **table of content** (toc) option in the YAML header

* Add any modification you want (text, formatting, ...)

* **knit** !

---

class: inverse, center, middle

# THANK YOU !

--
*slides created with the [xaringan package](https://github.com/yihui/xaringan)*