r - 如何在 shiny 中创建一个简单的下拉菜单？

Question

因此，在我 Shiny 的应用程序的 tabsetpanel 内的三个选项卡面板中，我有三个下载按钮。有什么办法我不能创建下拉菜单而不是这些选项卡面板？我不想弄乱输出，只是以下拉菜单而不是选项卡面板的形式组织下面的代码。

tabsetPanel(tabPanel("download 1", downloadBttn("downloadData",size="sm","Download1"),tabPanel("download 2",downloadBttn("downloadData",size="sm","Download2"),tabPanel("download 3",downloadBttn("downloadData",size="sm","Download3"))

Answer 1

使用选择输入，以便用户只需从下拉框中选择要下载的数据。无需单独的选项卡即可下载数据

library(shiny)

ui <- fluidPage(
  selectInput("download", "Select Data to download", choices = c("euro", "mtcars", "iris")),
  downloadButton("downloadData")
)

server <- function(input, output, session) {

  dataDownload <- reactive({
    switch(input$download,
           "euro" = euro,
           "mtcars" = mtcars,
           "iris" = iris)
  })

  output$downloadData <- downloadHandler(
    filename = function() {
      paste(input$download, ".csv", sep = "")
    },
    content = function(file) {
      write.csv(dataDownload(), file, row.names = FALSE)
    }
  )

}

shinyApp(ui, server)