Introduction to Shiny Apps

Shiny is an R package that allows you to build interactive web applications directly from R. It is widely used for data visualization and reporting.

Installing and Loading Shiny

Before using Shiny, install and load the package.

install.packages('shiny')
library(shiny)

Basic Structure of a Shiny App

A Shiny app consists of two main parts:

• UI (User Interface): Defines the layout and appearance.
• Server: Contains the logic and computations.

Creating a Simple Shiny App

Use shinyApp() to create a basic interactive application.

library(shiny)
ui <- fluidPage(
  titlePanel('Hello Shiny!'),
  sidebarLayout(
    sidebarPanel(sliderInput('num', 'Choose a number:', 1, 100, 50)),
    mainPanel(textOutput('value'))
  )
)
server <- function(input, output) {
  output$value <- renderText({ paste('You selected:', input$num) })
}
shinyApp(ui = ui, server = server)

Adding Reactive Elements

Reactive expressions update automatically when inputs change.

server <- function(input, output) {
  reactive_text <- reactive({ paste('Your number squared is:', input$num^2) })
  output$value <- renderText({ reactive_text() })
}

Creating Interactive Plots

Use renderPlot() to display interactive plots.

server <- function(input, output) {
  output$plot <- renderPlot({
    hist(rnorm(input$num), col='blue', main='Random Histogram')
  })
}

Running a Shiny App

Save your script as app.R and run it using shiny::runApp().

Deploying a Shiny App

Shiny apps can be deployed online using shinyapps.io or hosted on a Shiny server.

Summary

In this lesson, you learned:

• How to create and structure a Shiny app.
• How to use reactive elements for interactivity.
• How to deploy a Shiny app online.