• Shiny is a web application framework for R.
• Shiny allows you to create a graphical interface so that users can interact with your visualizations, models, and algorithms without needed to know R themselves.
• Using Shiny, the time to create simple, yet powerful, web-based interactive data products in R is minimized.
• Shiny is made by the fine folks at R Studio.

Shiny doesn't really require it, but as with all web programming, a little knowledge of HTML, CSS and Javascript is very helpful.

• HTML gives a web page structure and sectioning as well as markup instructions
• CSS gives the style
• Javscript for interactivity

Shiny uses Bootstrap (no relation to the statistics bootstrap) style, which (to me) seems to look nice and renders well on mobile platforms.

If you're interested in learning more about HTML, CSS, and Javascript we recommend any one of the following resources:

• Mozilla Developer Network Tutorials
• HTML & CSS from Khan Academy
• Tutorials from Free Code Camp

• Make sure you have the latest release of R installed
• If on Windows, make sure that you have Rtools installed
• install.packages("shiny")
• library(shiny)
• Great tutorial at http://shiny.rstudio.com/tutorial/
• Basically, this lecture is walking through that tutorial offering some of our insights

A shiny project is a directory containing at least two files:

• ui.R (for user interface) controls how your app looks.
• server.R that controls what your app does.

library(shiny)
shinyUI(fluidPage(
  titlePanel("Data science FTW!"),
  sidebarLayout(
    sidebarPanel(
      h3("Sidebar Text")
    ),
    mainPanel(
      h3("Main Panel Text")
    )
  )
))

library(shiny)
shinyServer(function(input, output) {

})

• In R, change to the directories with these files and type runApp()
• or put the path to the directory as an argument
• It should open a browser window with the app running

Shiny provides several wrapper functions for using standard HTML tags in your ui.R, including h1() through h6(), p(), a(), div(), and span().

• See ?builder for more details.

library(shiny)
shinyUI(fluidPage(
  titlePanel("HTML Tags"),
  sidebarLayout(
    sidebarPanel(
      h1("H1 Text"),
      h3("H3 Text"),
      em("Emphasized Text")
    ),
    mainPanel(
      h3("Main Panel Text"),
      code("Some Code!")
    )
  )
))

Now that you've played around with customizing the look of your app, let's give it some functionality! Shiny provides several types of inputs including buttons, checkboxes, text boxes, and calendars. First let's experiment with the slider input. This simple app will display the number that is selected with a slider.

library(shiny)
shinyUI(fluidPage(
  titlePanel("Slider App"),
  sidebarLayout(
    sidebarPanel(
      h1("Move the Slider!"),
      sliderInput("slider1", "Slide Me!", 0, 100, 0)
    ),
    mainPanel(
      h3("Slider Value:"),
      textOutput("text")
    )
  )
))

library(shiny)
shinyServer(function(input, output) {
  output$text <- renderText(input$slider1)
})

ui.R

• sliderInput() specifies a slider that a user can manipulate
• testOutput() displays text that is rendered in server.R

server.R

• renderText() transforms UI input into text that can be displayed.

Notice that in ui.R input and output names are assigned with strings (sliderInput("slider1",..., textOutput("text")) and in server.R those components can be accessed with the $ operator: output$text <- renderText(input$slider1).

Allowing users to manipulate data and to see the results of their manipulations as a plot can be very useful. Shiny provides the plotOutput() function for ui.R and the renderPlot() function for sever.R for taking user input and creating plots.

library(shiny)
shinyUI(fluidPage(
  titlePanel("Plot Random Numbers"),
  sidebarLayout(
    sidebarPanel(
      numericInput("numeric", "How Many Random Numbers Should be Plotted?", 
                   value = 1000, min = 1, max = 1000, step = 1),
      sliderInput("sliderX", "Pick Minimum and Maximum X Values",
                  -100, 100, value = c(-50, 50)),
# ...

# ...
      sliderInput("sliderY", "Pick Minimum and Maximum Y Values",
                  -100, 100, value = c(-50, 50)),
      checkboxInput("show_xlab", "Show/Hide X Axis Label", value = TRUE),
      checkboxInput("show_ylab", "Show/Hide Y Axis Label", value = TRUE),
      checkboxInput("show_title", "Show/Hide Title")
    ),
    mainPanel(
      h3("Graph of Random Points"),
      plotOutput("plot1")
    )
  )
))

library(shiny)
shinyServer(function(input, output) {
  output$plot1 <- renderPlot({
    set.seed(2016-05-25)
    number_of_points <- input$numeric
    minX <- input$sliderX[1]
    maxX <- input$sliderX[2]
    minY <- input$sliderY[1]
    maxY <- input$sliderY[2]
# ...

# ...
    dataX <- runif(number_of_points, minX, maxX)
    dataY <- runif(number_of_points, minY, maxY)
    xlab <- ifelse(input$show_xlab, "X Axis", "")
    ylab <- ifelse(input$show_ylab, "Y Axis", "")
    main <- ifelse(input$show_title, "Title", "")
    plot(dataX, dataY, xlab = xlab, ylab = ylab, main = main,
         xlim = c(-100, 100), ylim = c(-100, 100))
  })
})

ui.R

• numericInput() allows the user to enter any number
• checkboxInput() creates boxes that can be checked
• plotOutput() displays a plot

server.R

• renderPlot() wraps the creation of a plot so it can be displayed

• Reactivity
• Advanced UI
• Interactive Graphics

• OpenCPU by Jerome Ooms, is a really neat project providing an API for calling R from web documents