20-packages.Rmd

# Packages

> A package is just a lightweight set of conventions that unlock useful tools and workflows.

## Package Structure

The most simple package contains a `DESCRIPTION` file, housing metadata about the package (e.g. name and authors), and an `R/` directory where `.R` files with function definitions live. 

Packages may also contain:

* A `data/` directory, which holds reference datasets.
* A `tests/` directory, which holds unit-tests that are used to ensure code works as expected.
* A `vignettes/` directory, which holds long-form documentation.
* More! Read Hadley Wickham and Jenny Bryan's **amazing** book, [R Packages](https://r-pkgs.org)

## Benefits

In general, packages are beneficial for easily sharing your work. Packages provide a common organizational structure and offer improved workflow for loading and launching Shiny applications.

## Converting an existing app

1. Call [`usethis::create_package("pick-a-path")`](https://r-pkgs.org/whole-game.html#create_package). This will create the package directory and skeleton. 
2. Remove any `library()` or `require()` calls, in favor of `usethis::use_package("name")`.
3. If your app uses modules, place related ones in individual `.R` files with `usethis::use_r("module-category")`. 
4. Wrap core app inside a function and place within a `.R` file, e.g:

```{r greeting-app, eval = FALSE}

greetingApp <- function() {
# define a user-interface with two elements: a text input with an ID, 
# label, and initial value; define a textOutput that 
# returns the input + greeting
ui <- fluidPage(
  textInput(inputId = "nameInput", 
            label = "What is your name?", 
            value = "World"),
  textOutput("name")
)

# define the server side logic to manipulate the inputs
server <- function(input, output, session) {
  # define the output that concatenates the strings 
  # "Hello, " + user input + "."
  output$name <- renderText({paste0("Hello, ", input$nameInput, ".")})
}

# run the application
shinyApp(ui, server)
}
```

5. Call `devtools::load_all()` and your function -- `greetingApp()` to say hello to your package!

## Example: shinysurveys

> shinysurveys provides easy-to-use, minimalistic code for creating and deploying surveys in Shiny.

### Installation

You can install {shinysurveys} via CRAN or GitHub and load it as follows:

``` {.r}
# Install released version from CRAN
install.packages("shinysurveys")

# Or, install the development version from GitHub
remotes::install_github("jdtrat/shinysurveys")

# Load package
library(shinysurveys)
```

### Demo

A survey made with shinysurveys package might look like this:

![](https://www.jdtrat.com/project/shinysurveys/shinysurveys-final-demo.gif)
You can run a demo survey with the function `shinysurveys::demo_survey()`.

### Let's take a look!

* Live walk-through of creating an app with shinysurveys, how everything is packaged together, and more!


## Meeting Videos

### Cohort 1

`r knitr::include_url("https://www.youtube.com/embed/IRkgCUvvFQ4")`

<details>
  <summary> Meeting chat log </summary>
  
```
00:16:10	Russ Hyde:	Hi everyone
00:25:15	Robert Overman:	In the past the app itself had to be put into the inst folder of the package
00:27:41	Robert Overman:	So now being able to put it into the R folder makes things a lot easier, than having to do the odd reference back to runapp having it find the source file location to pull the server and ui
00:37:53	Jonathan Trattner:	https://github.com/jdtrat/shinysurveys
```
</details>


### Cohort 3

`r knitr::include_url("https://www.youtube.com/embed/CDSDAVye-Fk")`

<details>
  <summary>Meeting chat log</summary>
```
00:46:57	Brendan Lam:	Your tutorial was helpful, thanks!
```
</details>


### Cohort 4

`r knitr::include_url("https://www.youtube.com/embed/_POCL1OHvyw")`

<details>
  <summary>Meeting chat log</summary>
```
00:33:30	Lydia Gibson:	Hello
00:34:25	Trevin Flickinger:	start
00:50:01	Trevin Flickinger:	“Using @import is not generally considered best practice, but it makes sense here”
01:07:08	Lydia Gibson:	Need to drop for another meeting. See you next week
01:08:22	Trevin Flickinger:	Lydia dropped off the call
01:16:21	Trevin Flickinger:	stop
```
</details>


### Cohort 5

`r knitr::include_url("https://www.youtube.com/embed/URL")`

<details>
  <summary>Meeting chat log</summary>
```
LOG
```
</details>