Question

该代码仅在我添加变量并首次删除时才起作用。删除该变量后，它返回到选择“添加到地块”中，然后无法将其添加回去，我想当我更新updateSelectInput时，出现了问题。加selectRemove为空时需要删除。如何通过两种方式进行更新？

library(shiny)

mtcars_1 <- mtcars[,c("mpg", "disp", "hp", "drat", "wt", "qsec")]

runApp(list(
  ui=pageWithSidebar(headerPanel("Adding and Removing Variables"),

                     sidebarPanel(

                       selectInput(inputId = "selectAdd", label = "Add to the plot",
                                   choices = c(names(mtcars_1)),
                                   selected = names(mtcars_1)[1]),

                       actionButton(inputId = "add", label = "Add to the plot")
                     ),


                     mainPanel(
                       textOutput("text"),hr(),
                       uiOutput("remove_list")
                     )
  ),

  server=function(input, output, session) {

    rv <- reactiveValues(add_v = c())
    observeEvent(input$add,{
      rv$add_v <- rbind(rv$add_v,input$selectAdd)
    })

    rv <- reactiveValues(rem_v = c())
    observeEvent(input$remove,{
      rv$rem_v <- rbind(rv$rem_v,input$selectRemove)
    })

    observe({
      value_add <- c(names(mtcars_1)[!names(mtcars_1) %in% rv$add_v ],rv$rem_v)
      value_rem <-c(rv$add_v[! rv$add_v %in% rv$rem_v])

      updateSelectInput(session,"selectAdd",choices = value_add)
      updateSelectInput(session,"selectRemove",choices = value_rem)
    })

    output$remove_list <- renderUI({

      if(length(rv$add_v) > 0){
        tagList(
          selectInput(inputId = "selectRemove", label = "Remove to the plot",
                      choices = c(rv$add_v),
                      selected = rv$add_v[1]),

          actionButton(inputId = "remove", label = "Remove to the plot")
        )
      }

    })

    output$text <- renderText({
      c(rv$add_v[! rv$add_v %in% rv$rem_v])

    })

  }))

Answer 1

欢迎来到stackoverflow！

您快到了-但是，您对reactiveValues的更新逻辑还不完整。对于每个按钮单击，您都必须将一个对象添加到一个值，然后将其从另一个值中删除。请检查以下内容：

library(shiny)

mtcars_1 <- mtcars[, c("mpg", "disp", "hp", "drat", "wt", "qsec")]

runApp(list(
  ui = pageWithSidebar(
    headerPanel("Adding and Removing Variables"),
    sidebarPanel(
      selectInput(
        inputId = "selectAdd",
        label = "Add to the plot",
        choices = names(mtcars_1),
        selected = names(mtcars_1)[1]
      ),
      actionButton(inputId = "add", label = "Add to the plot")
    ),
    mainPanel(textOutput("text"), hr(),
              uiOutput("remove_list"))
  ),

  server = function(input, output, session) {

    rv <- reactiveValues(add_v = NULL, rem_v = names(mtcars_1))

    observeEvent(input$add, {
      rv$rem_v <- setdiff(rv$rem_v, input$selectAdd)
      rv$add_v <- union(rv$add_v, input$selectAdd)
    })

    observeEvent(input$remove, {
      rv$add_v <- setdiff(rv$add_v, input$selectRemove)
      rv$rem_v <- union(rv$rem_v, input$selectRemove)
    })

    observe({
      updateSelectInput(session, "selectAdd", choices = rv$rem_v)
      updateSelectInput(session, "selectRemove", choices = rv$add_v)
    })

    output$remove_list <- renderUI({
      if (length(rv$add_v) > 0) {
        tagList(
          selectInput(
            inputId = "selectRemove",
            label = "Remove to the plot",
            choices = c(rv$add_v),
            selected = rv$add_v[1]
          ),
          actionButton(inputId = "remove", label = "Remove to the plot")
        )
      }
    })

    output$text <- renderText({
      c(rv$add_v[!rv$add_v %in% rv$rem_v])
    })

  }
))

在Shiny中添加和删除元素

1 个答案: