Question

我有一个允许用户上传数据的应用程序，然后有一个操作按钮来触发一些计算。然后，我有一些进度条向用户显示该过程将花费多长时间。计算完成后，我想添加一个下载按钮，以便用户可以下载计算结果。

我不确定如何访问在观察事件函数中创建的数据表，以便可以在downloadhandler函数中使用它？

这是我的代码：

server <- function(input, output) {
  options(shiny.maxRequestSize=200*1024^2)

  file_name <- reactive({
    inFile <- input$file1

    if (is.null(inFile))
      return(NULL)

    return (stringi::stri_extract_first(str = inFile$name, regex = ".*(?=\\.)"))
  })

  output$myFileName <- renderText({ paste("Claim data selected:",file_name()) })

  mydata <- reactive({
    inFile <- input$file1
    if (is.null(inFile))
      return(NULL)
    tbl <- read.csv(inFile$datapath,sep=";")
    return(tbl)
  })

  output$my_output_data <- DT::renderDataTable({
    mydata() },
    options = list(
      lengthChange = FALSE,
      autowidth = TRUE,
      columnDefs = list(list(width = '70%', targets = 1)))
  )

  output$summary <- renderText({    
    dt.size <- nrow({mydata()})
    paste("There are",dt.size,"records.", sep =" ")
  })

  observeEvent(input$goButton1,{
    output$table1 <- DT::renderDataTable({
    withProgress(message = 'Calculation in progress...',
                 value = 0, {function1({mydata()},progress=TRUE)})
  })

  output$table1 <- DT::renderDataTable(function1({mydata()}))

  output$downloadData <- downloadHandler(
    filename = function() { 
      paste("DLR result-", Sys.Date(), ".csv", sep="")
    },
    content = function(file) {
      #fwrite("output$table 1 should be here", file)
  })  

})

}

Answer 1

给定代码的问题是data.table库中的fread函数采用了data.frame或data.table参数。在这里，您给了它一个DT javascript DataTable对象。我的代码使用基本R data.frames而不是data.table，但是您应该能够对其进行相应的调整。

library(shiny)
library(shinydashboard)

ui = dashboardPage(
    dashboardHeader(title = "File Download"),
    dashboardSidebar(),
    dashboardBody(
        fluidPage(
            fluidRow(
                box(width=12,
                    title = "UploadDownload",
                    fileInput("file1", label="File1 upload"),
                    downloadButton("downloadData", "Download")
                )
            ),
            fluidRow(
                box(width=12,
                    title = "DataTable", 
                    textOutput("myFileName"),
                    DT::dataTableOutput("my_output_data")
                )
            )
        )
    )
)

server = function(input, output) {

    file_name = reactive({
        req(input$file1)
        return(gsub("\\..*$", "", input$file1$name))
    })

    output$myFileName = renderText({ 
        paste("Claim data selected:",file_name()) 
    })

    mydata = reactive ({
        req(input$file1) 
        tbl = read.csv(input$file1$datapath)
        return(tbl)

    })

    mydata2 = reactive ({
       tbl = mydata() 
       # a calculation that will take some time
        withProgress(message="Adding another column", detail="this may take some time", 
                     {
                         n = dim(tbl)[2]
                         tbl$newcolumn = NULL
                         for (i in 1:n) {
                             tbl$newcolumn[i] = sample.int(10,1)
                             incProgress(1/n)
                             Sys.sleep(5/n)
                         }
                     })
    })

    output$my_output_data = DT::renderDataTable(
        mydata(),
        options = list(
            lengthChange=FALSE,
            autowidth=TRUE,
            columnDefs=list(list(width='70%', targets=1))
        )
    )

    output$downloadData = downloadHandler(
        filename = function() {
            paste("DLR results-", Sys.Date(), ".csv", sep="")
        },
        content = function(file) {
            write.csv(mydata2(), file)
        }
    )

}

shinyApp(ui, server)

在观察事件中使用带有数据框的下载按钮

1 个答案: