Introduction to Shiny

Building Interactive Web Applications in R

NING LI

2023-04-07

Agenda

  • Introduction to Shiny

  • Shiny architecture

  • Creating a simple Shiny app

  • Advanced features

  • Summary and Q&A

Introduction to Shiny

  • Shiny is an open-source R package developed by RStudio that allows developers to build interactive web apps straight from R.

  • It simplifies the process of integrating R code with HTML.

  • It doesn’t require knowledge of HTML or JavaScript, although such knowledge can enhance customization.

Shiny Architecture

  • Shiny apps consist of two main components: the UI (User Interface) and the server.

  • The UI defines the layout and appearance of the app.

  • The server contains the instructions required to build the app.

UI

Creating a Simple Shiny App - UI

Code

# load shiny package
library("shiny")

# Define UI
ui <- fluidPage(
  titlePanel("My first Shiny App"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("obs", "Number of observations:", min = 0, max = 1000, value = 500)
    ),
    mainPanel(plotOutput("distPlot"))
  )
)

Outline

  • fluidPage(): creates a new page that automatically adjusts its layout to the browser’s dimensions.

  • titlePanel(): sets the title.

  • sidebarLayout(), sidebarPanel(): create a sidebar.

  • sliderInput(): creates an interactive slider.

Server

Creating a Simple Shiny App - Server

Code

# Define server logic 
server <- function(input, output) {
  output$distPlot <- renderPlot({
    hist(rnorm(input$obs))
  })
}

Outline

  • server: This function contains the processing logic of the app.

  • output$distPlot: The output object is modified to include a plot named distPlot.

  • renderPlot(): This function is used to render the plot.

  • hist(rnorm(input$obs)): Generate a histogram based on the input value from the slider.

Running the App

# Run the application 
shinyApp(ui = ui, server = server)
  • shinyApp(): This function takes the UI and server to start the Shiny app.

Advanced Features

  • Reactivity: One of the key features of Shiny is its built-in reactivity. This means when an input changes, the output changes automatically in response.

  • Widgets: Shiny includes a variety of widgets for inputs like checkboxes, sliders, and more.

  • Customization: With knowledge of HTML, CSS, and JavaScript, you can customize the appearance and functionality of your Shiny app far beyond the basic capabilities.

Summary

  • Shiny is a powerful tool for creating interactive web applications using R.

  • Shiny apps have two components, a UI and a server.

  • Reactive programming in Shiny allows for automatic updates when inputs change.

Q&A

  • Now that we’ve covered the basics of Shiny and how to create an app, let’s open the floor for discussion.

  • Any queries, doubts, or ideas you’d like to share or discuss? Let’s dive into it!

Reference

https://datalabzone.com