Shiny Example 07_widgets

server.R

library(shiny)
library(datasets)

# Define server logic required to summarize and view the selected dataset
shinyServer(function(input, output) {
  
  # Return the requested dataset
  datasetInput <- reactive({
    switch(input$dataset,
           "rock" = rock,
           "pressure" = pressure,
           "cars" = cars)
  })
  
  # Generate a summary of the dataset
  output$summary <- renderPrint({
    dataset <- datasetInput()
    summary(dataset)
  })
  
  # Show the first "n" observations
  output$view <- renderTable({
    head(datasetInput(), n = input$obs)
  })
})

ui.R

library(shiny)

# Define UI for dataset viewer application
shinyUI(fluidPage(
  
  # Application title.
  titlePanel("More Widgets"),
  
  # Sidebar with controls to select a dataset and specify the number
  # of observations to view. The helpText function is also used to 
  # include clarifying text. Most notably, the inclusion of a 
  # submitButton defers the rendering of output until the user 
  # explicitly clicks the button (rather than doing it immediately
  # when inputs change). This is useful if the computations required
  # to render output are inordinately time-consuming.
  sidebarLayout(
    sidebarPanel(
      selectInput("dataset", "Choose a dataset:", 
                  choices = c("rock", "pressure", "cars")),
      
      numericInput("obs", "Number of observations to view:", 10),
      
      helpText("Note: while the data view will show only the specified",
               "number of observations, the summary will still be based",
               "on the full dataset."),
      
      submitButton("Update View")
    ),
    
    # Show a summary of the dataset and an HTML table with the requested
    # number of observations. Note the use of the h4 function to provide
    # an additional header above each output section.
    mainPanel(
      h4("Summary"),
      verbatimTextOutput("summary"),
      
      h4("Observations"),
      tableOutput("view")
    )
  )
))