Shiny

Shiny is an R package that makes it easy to build interactive web apps straight from R. You can host standalone apps on a webpage or embed them in R Markdown documents or build dashboards. You can also extend your Shiny apps with CSS themes, htmlwidgets, and JavaScript actions.

Shiny App

Anatomy of an App

library(shiny)

shinyApp(
  ui = list(),
  
  server = function(input, output, session) {
  
  }
)

Demo 01 - A Basic Example

library(tidyverse)
library(shiny)
d = readr::read_csv(here::here("data/weather.csv"))

shinyApp(
  ui = fluidPage(
    titlePanel("Temperature Forecasts"),
    sidebarLayout(
      sidebarPanel(
        radioButtons(
          "city", "Select a city",
          choices = c("Chicago", "Durham", "Sedona", "New York", "Los Angeles")
        ) 
      ),
      mainPanel( 
        plotOutput("plot")
      )
    )
  ),
  server = function(input, output, session) {
    output$plot = renderPlot({
      d |>
        filter(city %in% input$city) |>
        ggplot(aes(x=time, y=temp, color=city)) +
        geom_line()
    })
  }
)

Your turn - Exercise 01

Copy the code from the previous slide (or open exercises/ex01.R) and try running it using the Run App button.

Check that you are able successfully run the shiny app and are able to interact with it.

• If everything is working try modifying the code (e.g. try adding or removing a city from radioButtons()).

• What happens if you add a city that is not in the weather.csv data set to the radio button input?

Troubleshooting

A couple of quick tips:

• If the app can’t find the data, make sure you have opened the workshop’s RStudio project

• Make sure you have the latest versions of shiny and tidyverse installed

• If you are stuck, ask a neighbor for help and/or raise your hand and myself or a TA will come by