AE 21: Building a Shiny weather app

Suggested answers

Application exercise
Answers
Modified

April 17, 2026

Exercise 01

library(tidyverse)
library(shiny)
library(bslib)

d <- read_csv(here::here("data/weather.csv"))

ui <- page_sidebar(
  title = "Temperatures at Major Airports",
  sidebar = sidebar(
    radioButtons(
      inputId = "name",
      label = "Select an airport",
      choices = c(
        "Hartsfield-Jackson Atlanta",
        "Raleigh-Durham",
        "Denver",
        "Los Angeles",
        "John F. Kennedy",
        "Savannah"
      )
    )
  ),
  plotOutput("plot")
)

server <- function(input, output, session) {
  output$plot <- renderPlot({
    d |>
      filter(name %in% input$name) |>
      ggplot(mapping = aes(x = date, y = temp_avg)) +
      geom_line()
  })
}

shinyApp(ui = ui, server = server)

Exercise 02

library(tidyverse)
library(shiny)
library(bslib)

d <- read_csv(here::here("data/weather.csv"))

ui <- page_sidebar(
  title = "Temperatures at Major Airports",
  sidebar = sidebar(
    selectInput(
      inputId = "name",
      label = "Select an airport",
      choices = c(
        "Hartsfield-Jackson Atlanta",
        "Raleigh-Durham",
        "Denver",
        "Los Angeles",
        "John F. Kennedy"
      ),
      multiple = TRUE
    )
  ),
  plotOutput("plot")
)

server <- function(input, output, session) {
  output$plot <- renderPlot({
    d |>
      filter(name %in% input$name) |>
      ggplot(mapping = aes(x = date, y = temp_avg, color = name)) +
      geom_line()
  })
}

shinyApp(ui = ui, server = server)

Exercise 03

library(tidyverse)
library(shiny)
library(bslib)

d <- read_csv(here::here("data/weather.csv"))

d_vars <- c(
  "Average temp" = "temp_avg",
  "Min temp" = "temp_min",
  "Max temp" = "temp_max",
  "Total precip" = "precip",
  "Snow depth" = "snow",
  "Wind direction" = "wind_direction",
  "Wind speed" = "wind_speed",
  "Air pressure" = "air_press"
)

ui <- page_sidebar(
  title = "Weather Forecasts",
  sidebar = sidebar(
    radioButtons(
      "name",
      "Select an airport",
      choices = c(
        "Raleigh-Durham",
        "Houston Intercontinental",
        "Denver",
        "Los Angeles",
        "John F. Kennedy"
      )
    ),
    selectInput(
      "var",
      "Select a variable",
      choices = d_vars,
      selected = "temp_avg"
    )
  ),
  plotOutput("plot"),
  tableOutput("minmax")
)

server <- function(input, output, session) {
  output$plot <- renderPlot({
    d |>
      filter(name %in% input$name) |>
      ggplot(mapping = aes(x = date, y = .data[[input$var]])) +
      geom_line() +
      labs(title = str_c(input$name, "-", input$var))
  })

  output$minmax <- renderTable({
    d |>
      filter(name %in% input$name) |>
      mutate(
        year = year(date) |> as.integer()
      ) |>
      summarize(
        `min avg temp` = min(temp_min),
        `max avg temp` = max(temp_max),
        .by = year
      )
  })
}

shinyApp(ui = ui, server = server)

Acknowledgments