rstudio-snippets.Rmd

# RStudio code snippets

In RStudio, __code snippets__ are text macros that you can use to insert bits of commonly used code. Here, we'll walk you through the creation of two snippets:

* A snippet to add in `library(tidyverse)`
* A snippet to start an R script

You can use the same process to create any snippet you want.

## `tv` snippet

* Go to _Tools_ > _Global Options..._ > _Code_, and find the _Snippets_ section. 
* Make sure _Enable code snippets_ is checked.
* Click on _Edit Snippets..._.

```{r echo=FALSE, image_dpi=125}
knitr::include_graphics("images/rstudio-snippets/preferences_wizard.png")
```

* Scroll down to the bottom of the snippet editor to add your snippet.
* Paste in the following code to create a `library(tidyverse)` snippet named `tv`:

```{}
snippet tv
  library(tidyverse)
```

Note that every line after `snippet [snippet name]` must start with a single tab.

```{r echo=FALSE, image_dpi=125}
knitr::include_graphics("images/rstudio-snippets/tv_snippet.png")
```

* Click _Save_ and exit the _Preferences_ window.

Now, you can use your snippet. In the console, an RMarkdown document, or an R script, type `tv` then hit tab. `library(tidyverse)` should appear.

## `rscript` snippet

We used a script template to create the scripts in our [example project](https://github.com/dcl-docs/project-example). Each script has a section for parameters and a section for code, separated by a line. There are spots for the description, author, and version.  

Here's what the script template looks like:

```{r, eval=FALSE}
# Description

# Author: Name
# Version: 2021-09-08

# Packages
library(tidyverse)

# Parameters

#===============================================================================

# Code
```

Because the script template has elements for the user to fill in, the `rscript` snippet is going to be more complicated than the `tv` snippet.

* Follow the steps from the previous section to open the snippet editor.
* Paste in the following code to create a snippet named `rscript`:

```{r, eval=FALSE}
snippet rscript
  # ${1:Description}
	
  # Author: ${2:Name}
  # Version: `r Sys.Date()`
	
  # Packages
  library(tidyverse)
	
  # Parameters
	
  # ============================================================================
	
  ${3:# Code}
```

```{r echo=FALSE, image_dpi=125}
knitr::include_graphics("images/rstudio-snippets/rscript_snippet.png")
```

The `${}` components create variables. As you'll see later, when you use the snippet, you can tab through these variables to fill them in. The numbers inside the `{}`s define the order in which you can tab through them.

* Click _Save_ and exit the _Preferences_ window.

Now, you can use your snippet. 

* Type `rscript` and then hit tab. The script template should appear.
* Fill in your variables (if the snippet has any). You can tab to automatically move the cursor to the next variable. 

```{r echo=FALSE, image_dpi=125}
knitr::include_graphics("images/rstudio-snippets/rscript_snippet_done.png")
``` 

You shouldn't have to type out `rscript` everytime you want to use the snippet. If you type out a portion of `rscript`, the name of the snippet should appear and you can hit tab to select the snippet.

```{r echo=FALSE, image_dpi=125}
knitr::include_graphics("images/rstudio-snippets/rscript_snippet_popup.png")
```