更新复选框组输入不适用于多个复选框

Question

为什么这个 updateCheckboxGroupInput() 代码在超过 1 个复选框被选中时不起作用。从上面的组中选择一个复选框时，下面的框应更新以显示更多特定的条目。但是如果在顶部选择了多个复选框，代码就会失败。任何人都知道问题可能是什么？

从这里或 bitbucket 复制：https://bitbucket.org/snippets/afolabicrystal/deyay5

  ui <- fluidPage(
p("The first checkbox group controls the second"),
checkboxGroupInput("inCheckboxGroup", "Device Class",
                   c("TV", "Mobile", "Tablet")),
checkboxGroupInput("inCheckboxGroup2", "Device Types",
                   c("Amazon TV", "Apple TV", "Android Phone", "iPhone", "iPad", "Android Tablet")))


  server <- function(input, output, session) {
observe({
  x <- input$inCheckboxGroup


  # Can also set the label and select items
  updateCheckboxGroupInput(session, "inCheckboxGroup2",
                           label = paste("Device Types", length(x)),
                           if ('TV' %in% x) {
                             choices = c("Amazon TV", "Apple TV")
                           } else if("Mobile" %in% x) {
                             choices = c("Android Phone", "iPhone")
                           } else if("Tablet" %in% x) {
                             choices = c("iPad", "Android Tablet")
                           } else if (all(c("TV","Mobile") %in% x)) {
                             choices = c("Amazon TV", "Apple TV", "Android Phone", "iPhone")
                           } else if (all(c("TV","Tablet") %in% x)) {
                             choices = c("Amazon TV", "Apple TV", "iPad", "Android Tablet")
                           } else if (all(c("Mobile","Tablet") %in% x)) {
                             choices = c("Android Phone", "iPhone", "iPad", "Android Tablet")
                           } else if (all(c("TV", "Mobile", "Tablet") %in% x)) {
                             choices = c("Amazon TV", "Apple TV", "Android Phone", "iPhone", "iPad", "Android Tablet")
                           } else {
                             choices = character(0)
                           },
                           selected = choices
  )
})
}
shinyApp(ui, server)

Answer 1

问题是您一直在使用 else if；一旦评估了其中一个 ifs，其余的就会被跳过。基本上你是在说：如果 x 为真，则执行 y。但是，如果 x 不为真（否则），检查 z 是否为真，等等...因此，如果 x 实际上为真，则永远不会评估 z。我希望这个解释有意义。

此外，您还可以通过检查三个条件（电视、手机和平板电脑）来简化代码，如果复选框被选中，则将选项添加到向量中。

下面给出了一个工作示例。希望这对您有所帮助！

ui <- fluidPage(
  p("The first checkbox group controls the second"),
  checkboxGroupInput("inCheckboxGroup", "Device Class",
                     c("TV", "Mobile", "Tablet")),
  checkboxGroupInput("inCheckboxGroup2", "Device Types",
                     c())
)


server <- function(input, output, session) {
  observe({
    x <- input$inCheckboxGroup

    choices=c()
    if ('TV' %in% x) 
      choices = c(choices,c("Amazon TV", "Apple TV"))
    if("Mobile" %in% x) 
      choices =c(choices, c("Android Phone", "iPhone"))
    if("Tablet" %in% x) 
      choices = c(choices,c("iPad", "Android Tablet"))

    updateCheckboxGroupInput(session, "inCheckboxGroup2",
                             label = paste("Device Types", length(x)),
                             choices=choices,
                             selected = choices
    )
  })
}
shinyApp(ui, server)

更新复选框组输入不适用于多个复选框

Update Checkbox Group Input Not Working for More than One Checkbox

r

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