R 闪亮：updateSelectInput不会针对不同的selectInput条件进行更新

根据第一个selectInput函数中选择的绘图类型，更新侧栏中（可选）数据框的列名时出现问题。 ColName只更新一次，这意味着x变量仅对第一种打印类型可见，y或Difference变量仅对第二种打印类型有效。第三种打印类型不提供任何选择

PS：从今天开始，我是stackoverflow新手-我希望下面的示例提供足够的信息。提前谢谢

ui <- fluidPage(
sidebarLayout(
sidebarPanel(
  selectInput(inputId = "plottype",
              label = "Choose your favorite plot type",
              choices = c("Histogram" = 1,
                          "Scatterplot" = 2,
                          "Whatever" = 3)),
  conditionalPanel(
    condition = "input.plottype == 1",
    selectInput(inputId = "x_var",
                label = "X-variable",
                choices = ""),
    uiOutput("choose_columns_1")),

  conditionalPanel(
    condition = "input.plottype == 2",
    selectInput(inputId = "x_var",
                label = "X-variable",
                choices = ""),
    selectInput(inputId = "y_var",
                label = "Y-variable",
                choices = ""),
    selectInput(inputId = "fill",
                label = "Distinguish",
                choices = ""),
    uiOutput("choose_columns_2")),

  conditionalPanel(
    condition = "input.plottype == 3",
    selectInput(inputId = "x_var",
                label = "X-variable",
                choices = ""),
    selectInput(inputId = "y_var",
                label = "Y-variable",
                choices = ""),
    selectInput(inputId = "fill",
                label = "Distinguish",
                choices = ""),
    uiOutput("choose_columns_3"))),

  mainPanel()
  )
 )

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

getData <- reactive({
if(is.null(input$file1)) return(mtcars)
req(input$file1)
req(input$sep)
req(input$quote)
read.csv(input$file1$datapath,
         header = TRUE,
         sep = input$sep,
         quote = input$quote)
})

observe({
dsnames <- names(getData())
cb_options <- list()
cb_options[dsnames] <- dsnames
updateSelectInput(session, "x_var",
                  label = "X-variable",
                  choices = cb_options,
                  selected = "")
updateSelectInput(session, "y_var",
                  label = "Y-variable",
                  choices = cb_options,
                  selected = "")
updateSelectInput(session, "fill",
                  label = "Distinguish",
                  choices = cb_options,
                  selected = "")
})



output$choose_columns_1 <- renderUI({
if(is.null(input$dataset))
  return()
colnames <- cb_options
updateSelectInput(session, "x_var",
                  label = "X-variable",
                  choices = colnames,
                  selected = "")
})


output$choose_columns_2 <- renderUI({
if(is.null(input$dataset))
  return()
colnames2 <- cb_options
updateSelectInput(session, "x_var",
                  label = "X-variable",
                  choices = colnames2,
                  selected = "")
updateSelectInput(session, "y_var",
                  label = "Y-variable",
                  choices = colnames2,
                  selected = "")
updateSelectInput(session, "fill",
                  label = "Distinguish",
                  choices = colnames2,
                  selected = "")
})

output$choose_columns_3 <- renderUI({
if(is.null(input$dataset))
  return()
colnames3 <- cb_options
updateSelectInput(session, "x_var",
                  label = "X-variable",
                  choices = colnames3,
                  selected = "")
updateSelectInput(session, "y_var",
                  label = "Y-variable",
                  choices = colnames3,
                  selected = "")
updateSelectInput(session, "fill",
                  label = "Distinguish",
                  choices = colnames3,
                  selected = "")
})

}

shinyApp(ui, server)

ui您可以尝试（使用三个数据集模拟您的需求）：

data\u set您看到了吗：内容来自哪里？@MLavoie谢谢您的评论！我已经看到了上面的链接，我的代码也包含了observe函数。我通过指定colname修改了链接中的这段代码，因为我想根据用户可以自己读取的数据集动态更改colname。“内容”是一个遗留的代码内容，现在被“cb_选项”替换，但仍然不起作用。如果查看文档
updateSelectInput（）
未在被动参数中使用，对不起，我不理解。你能告诉我更多或者举个简单的例子吗？谢谢在
选择input
中，您不提供任何选择。如果您添加选项，您的代码将正常工作。不清楚您为什么需要
updateSelectInput
。非常感谢您提供的代码。我的问题是，对于不同的条件面板，它仍然不能使用相同的uiOutput。例如，如果您将
uiOutput（“x_var”）
添加到ui中的最后一个条件面板（绘图类型2和3）。您需要在原始帖子中更加具体。代码按照您的要求执行。同一个uiOutput不能使用两次。啊！我不知道我不能使用相同的uiOutput两次！非常感谢你！帮了很多忙！
data_sets <- c("mtcars", "morley", "rock")

ui = fluidPage(
   sidebarLayout(
     sidebarPanel(
       uiOutput("choose_dataset"),
       selectInput(inputId = "plottype",
                   label = "Choose your favorite plot type",
                   choices = c("Histogram" = 1,
                               "Scatterplot" = 2,
                               "Whatever" = 3)),
       conditionalPanel(
         condition = "input.plottype == 1", uiOutput("x_var")),
       conditionalPanel(
         condition = "input.plottype == 2 || input.plottype == 3",
       uiOutput("y_var"), uiOutput("fill"))

     ),
     mainPanel()
   )
 )

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

   output$choose_dataset <- renderUI({
     selectInput("dataset", "Data set", as.list(data_sets))
   })


   output$x_var <- renderUI({
     # If missing input, return to avoid error later in function
     if(is.null(input$dataset))
       return()

     # Get the data set with the appropriate name
     dat <- get(input$dataset)
     colnames <- names(dat)

     # Create the checkboxes and select them all by default
     selectInput(inputId = "x_var",
                 label = "X-variable", 
                        choices  = colnames,
                        selected = colnames)
   })


   output$y_var <- renderUI({
     # If missing input, return to avoid error later in function
     if(is.null(input$dataset))
       return()

     # Get the data set with the appropriate name
     dat <- get(input$dataset)
     colnames <- names(dat)

     # Create the checkboxes and select them all by default
     selectInput(inputId = "y_var",
                 label = "Y-variable", 
                 choices  = colnames,
                 selected = colnames)
   })

   output$fill <- renderUI({
     # If missing input, return to avoid error later in function
     if(is.null(input$dataset))
       return()

     # Get the data set with the appropriate name
     dat <- get(input$dataset)
     colnames <- names(dat)

     # Create the checkboxes and select them all by default
     selectInput(inputId = "fill",
                 label = "Distinguish", 
                 choices  = colnames,
                 selected = colnames)
   })

}

 shinyApp(ui = ui, server = server)