R 如何在一个闪亮的应用程序中下载同一文件中的两个不同数据帧

我有一个基本的闪亮应用程序，我想在其中下载一个文件，其中包含两个不同的数据帧iris，mtcars。这可能吗？我不在乎哪一个会先显示还是第二个。在下面的vesrion中，文件被破坏了，但我这样添加它是为了更清楚地说明我想要什么

### ui.R

library(shiny)
pageWithSidebar(
  headerPanel('Iris k-means clustering'),
  sidebarPanel(
  uiOutput("ex") ,
  uiOutput("down")


  ),
  mainPanel(
    uiOutput('plot')

  )
)
#server.r
function(input, output, session) {
  output$ex<-renderUI({
      radioButtons("extension","File Format", choices = c("txt","csv","tsv","json"))

  })
  output$down<-renderUI({

      #Download files with quotes or not depending on the quote=input$quotes which has value TRUE or FALSE.
      output$downloadData <- downloadHandler(
        filename = function() {
          paste("file", input$extension, sep = ".")
        },

        # This function should write data to a file given to it by
        # the argument 'file'.
        content = function(file) {
          sep <- switch(input$extension,"txt"=",", "csv" = ",", "tsv" = "\t","json"=",")
          # Write to a file specified by the 'file' argument
          write.table(data.frame(iris,mtcars), file, sep = sep,
                      row.names = FALSE) 

        }

      )
      downloadButton("downloadData", "Download")
  })

}

---

正如@r2evans正确指出的那样，您只需在第一次调用后将append=TRUE添加到all write.table，以在一个文件中下载多个数据帧

服务器.r

---

由于帧不太可能是可rbind的不兼容维度，因此需要编写.tableiris，。。。然后编写.tablemtcars，append=TRUE，…。您的代码似乎无法工作。我只是得到了应用程序标题，没有任何功能。如果你删除mtcars并在浏览器中打开它，它就可以正常工作。它符合r2evans的建议。谢谢

server <- function(input, output, session) {
  output$ex<-renderUI({
    radioButtons("extension","File Format", choices = c("txt","csv","tsv","json"))

  })
  output$down<-renderUI({
    output$downloadData <- downloadHandler(

      #FileName
      filename = function() {
        paste("file", input$extension, sep = ".")
      },

      # This function should write data to a file given to it by
      # the argument 'file'.
      content = function(file) {
        sep <- switch(input$extension,"txt"=",", "csv" = ",", "tsv" = "\t","json"=",")

        write.table(iris, file, sep = sep, row.names = FALSE)
        write.table(mtcars, file, sep = sep, row.names = FALSE, append = TRUE)       

      }

    )
    downloadButton("downloadData", "Download")
  })

}