A Shiny example using a sliderInput in a sidebar layout with pre-processing done in global.R.

global.R

# Define a dataset globally which will be available 
# both to the UI and to the server.

# Rely on the 'WorldPhones' dataset in the datasets
# package (which generally comes preloaded).
library(datasets)


# Trim out the non-consecutive year from
# the 'WorldPhones' dataset (the first row).
myData <- WorldPhones[-1,]

server.R

library(shiny)

# Define a server for the Shiny app
shinyServer(function(input, output) {
  
  # Fill in the spot we created for a plot
  output$phonePlot <- renderPlot({
    
    # Render a barplot
    barplot(myData[as.character(input$year),]*1000, 
            main=paste("Phones in", input$year),
            ylab="Number of Telephones",
            xlab="Region",
            ylim=c(0,max(myData)*1000))
  })
})

ui.R

library(shiny)

# Store the years for the data as a numeric
years <- as.numeric(rownames(myData))

# Define the overall UI
shinyUI(
  
  # Use a fluid Bootstrap layout
  fluidPage(    
    
    # Give the page a title
    titlePanel("Telephones Around the World"),
    
    sidebarLayout(      
      
      # Define the sidebar with one input
      sidebarPanel(
        sliderInput("year", "Year:", 
                    min=min(years),
                    max=max(years),
                    value=min(years),
                    format="####",
                    animate=TRUE
                  ),
        hr(),
        helpText("Data from AT&T (1961) The World's Telephones.")
      ),
      
      # Create a spot for the barplot
      mainPanel(
        plotOutput("phonePlot")  
      )
      
    )
  )
)