server.r

library(shiny)
library(data.table)
# use the below options code if you wish to increase the file input limit, 
# in this example file input limit is increased from 5MB to 9MB
 options(shiny.maxRequestSize = 700*1024^2)

shinyServer(function(input,output){
  
  # This reactive function will take the inputs from UI.R and use them for read.table() to read the data from the file. It returns the dataset in the form of a dataframe.
  # file$datapath -> gives the path of the file
  data <- reactive({
    file1 <- input$file
    if(is.null(file1)){return()} 
    fread(input=file1$datapath, sep="auto", header = input$header, stringsAsFactors = input$stringAsFactors)
    
  })
  
  # this reactive output contains the summary of the dataset and display the summary in table format
  output$filedf <- renderTable({
    if(is.null(data())){return ()}
    input$file
  })
  
  # this reactive output contains the summary of the dataset and display the summary in table format
  output$sum <- renderTable({
    if(is.null(data())){return ()}
    summary(data())
    
     })
  
  # This reactive output contains the dataset and display the dataset in table format
  output$table <- renderTable({
    if(is.null(data())){return ()}
    data()
  })
  
  # the following renderUI is used to dynamically generate the tabsets when the file is loaded. Until the file is loaded, app will not show the tabset.
  output$tb <- renderUI({
    if(is.null(data()))
      h5("Powered by", tags$img(src='RStudio-Ball.png', heigth=200, width=200))
    else
      tabsetPanel(tabPanel("About file", tableOutput("filedf")),tabPanel("Data", tableOutput("table")),tabPanel("Summary", tableOutput("sum")))
  })
})

ui.r

library(shiny)
shinyUI(fluidPage(
  titlePanel("File Input"),
  sidebarLayout(
    sidebarPanel(
      fileInput("file","Upload the file"), # fileinput() function is used to get the file upload contorl option
      helpText("Default max. file size is 5MB"),
      tags$hr(),
      h5(helpText("Select the read.table parameters below")),
      checkboxInput(inputId = 'header', label = 'Header', value = FALSE),
      checkboxInput(inputId = "stringAsFactors", "stringAsFactors", FALSE),
      br(),
      radioButtons(inputId = 'sep', label = 'Separator', choices = c(Comma=',',Semicolon=';',Tab='\t', Space=''), selected = ',')
      ),
    mainPanel(
      uiOutput("tb")
      
# use below code if you want the tabset programming in the main panel. If so, then tabset will appear when the app loads for the first time.
#       tabsetPanel(tabPanel("Summary", verbatimTextOutput("sum")),
#                   tabPanel("Data", tableOutput("table")))
      )
    
    )
  ))