Web Apps in R Using Shiny

• A web application framework for R
• Written by Joe Cheng and RStudio
• First CRAN package up in 2012
• Delivers interactive experience over the web, all written in R!
• Ready for the enterprise

1. R and RStudio
2. Intermediate Understanding of R
   • Import/Export data, dplyr, ggplot
3. HTML, CSS, JavaScript not required, but helpful
4. Strategy for sharing (Markdown/Pres, Hosted/Private)

The shiny package!

Create a folder for your app and put all related files inside that folder. At minimum every Shiny app contains 2 parts:

1. A UI (client-side). Specified in a file called ui.R
2. Server Logic (server-side). Specified in a file called server.R

Take the bare minimum and add the following three items to your folder:

1. A file called global.R - Main location for loading packages, sharing data between ui and server sides, etc. ¹
2. A folder called www - Main location for all web resources in your application. If you would like to enforce a global standard of styling, then create a .css file containing a style sheet language for formatting.²
3. A folder called data - Main location for all data that your app uses. Especially important if not connecting to a database.

A ui.R file - holds the client-side logic

A server.R file - holds the server-side logic

shiny::runGitHub(repo = "com.packtpub.intro.r.bi",
                 username = "StevenMMortimer",
                 subdir = "Chapter8-ShinyDashboards/Ch8-BasicShinyApp")

reactivity

In the ui.R:

In the server.R:

1. One folder with ui.R, server.R, and other files and folders
   • All client-side elements go in ui.R
   • All server-side logic goes in server.R
2. Inputs and Outputs passed between
   • ui.R provides input$ that server.R accesses
   • server.R provides output$ that ui.R displays
3. reactivity invalidates cached values on server when inputs change¹

Shiny includes a grid-based layout framework based on the Bootstrap project.¹

The head tag - The head tag identifies a portion of the web page, usually not visible to the user, which contains the application title, icon, metadata, and scripts.

tags$head(
  tags$link(rel = "stylesheet", type = "text/css", 
            href = "app-styling.css")
)

The progress wheel - Lets the user know that app is processing their input.

shinysky::busyIndicator(text = "Calculation in progress ... ", wait = 0)

Custom JavaScript¹ & shinyjs - Extends interactivity and experience

Google Analytics Tracking - Setup an account and Google will give you Javascript snippet to embed to track users.

tags$script("
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-XXXXXXXX-1', 'auto');
ga('send', 'pageview');
")

Connecting to a database - Just like connecting to database from R or RStudio…

library(RPostgreSQL)
con <- dbConnect(dbDriver("PostgreSQL"), dbname = "postgres",
                 host = "localhost", port = 5432,
                 user = "user", password = 'password')
app_dat <- dbGetQuery(conn=con, statement="SELECT * FROM app.dat")
dbDisconnect(con)

shinyServer(function(input, output) {
...

The DT package - Highly interactive, functional tables based on

More examples available on https://rstudio.github.io/DT/

• Located on GitHub, in a Gist, or archived (e.g. .tar.gz)

Those options explained in more detail here

shiny::runGitHub(repo = "com.packtpub.intro.r.bi",
                 username = "StevenMMortimer",
                 subdir = "Chapter8-ShinyDashboards/Ch8-CampaignCreatorApp")

• Hosted For Free by Shinyapps.io

https://reportmort.shinyapps.io/campaign-creator-app/

• Hosted on a private server