Building apps

Building Web Applications with Shiny in R

Kaelen Medeiros

Data Scientist

Explore Life Expectation vs. GDP per Capita

An app displaying an interactive scatterplot of life expectation vs. gdp per capita for a selected continent and year

Explore Life Expectation vs. GDP per Capita

An app displaying an interactive table of life expectation, population, and gdp per capita for a selected continent and year

Building Shiny apps: 4 steps

Add inputs (UI)
Add outputs (UI/Server)
Update layout (UI)
Update outputs (Server)

Step 1: Add inputs (UI)

ui <- fluidPage(
  titlePanel("Life Expectation vs. GDP Per Capita"),

  selectInput('continent', 'Select Continent', unique(gapminder$continent)),

  sliderInput('year', 'Select Year', 1952, 2007, 1990, step = 5)
)

server <- function(input, output, session){

}
shinyApp(ui = ui, server = server)

An app displaying controls for selecting a continent and year

Step 2: Add outputs (UI)

ui <- fluidPage(
  titlePanel("Life Expectation vs. GDP Per Capita"),
  selectInput('continent', 'Select Continent', unique(gapminder$continent)),
  sliderInput('year', 'Select Year', 1952, 2007, 1990, step = 5),

  plotOutput('plot'),
  DT::DTOutput('table')

)

Step 2: Add outputs (Server)

server <- function(input, output, session){

  output$plot <- renderPlot({
    ggplot()
  })

  output$table <- DT::renderDT({
    gapminder
  })

}

An app displaying an empty plot and interactive table along with controls for selecting a continent and year

Step 3: Update layout (UI)

ui <- fluidPage(
  titlePanel("Life Expectation vs. GDP Per Capita"),

  sidebarLayout(

    sidebarPanel(
      selectInput('continent', 'Select Continent', unique(gapminder$continent)),
      sliderInput('year', 'Select Year', 1952, 2007, 1990, step = 5)
    ),

    mainPanel(
      plotOutput('plot'),
      DT::DTOutput('table')
    )

  )
)

Step 3: Update layout (UI)

ui <- fluidPage(
  titlePanel("Life Expectation vs. GDP Per Capita"),

  sidebarLayout(

    sidebarPanel(
      selectInput('continent', 'Select Continent', unique(gapminder$continent)),
      sliderInput('year', 'Select Year', 1952, 2007, 1990, step = 5)
    ),

    mainPanel(
      tabsetPanel(
        tabPanel("Plot", plotOutput('plot')),
        tabPanel("Table", DT::DTOutput('table'))
      )
    )

  )
)

An app displaying an interactive table of life expectancy, population, and gdp per capita for a selected continent and year

Step 4: Update outputs (Server)

server <- function(input, output, session){
  output$plot <- renderPlot({

    data <- gapminder %>% 
      filter(year == input$year) %>% 
      filter(continent == input$continent)
    print(data)
    ggplot(data, aes(x = gdpPercap, y = lifeExp)) +
      geom_point()

  })
  output$table <- DT::renderDT({

    gapminder %>% 
      filter(year == input$year) %>%
      filter(continent == input$continent) 
  })

}

An app displaying an interactive scatterplot of life expectancy vs. gdp per capita for a selected continent and year, in a tab

Let's practice!

Building Web Applications with Shiny in R