基于用户选择的输入数量的条件面板

Question

我正在尝试根据在多个 = TRUE 的 selectInput 中选择的条目数来填充不同数量的字段。因此，如果选择了“numfields”输入中的 1 个条目，则会出现第一个 conditionalPanel，依此类推。我现在所拥有的内容显示了我希望在没有任何用户输入的情况下成为有条件的输入。

  a <- c("A","B","C")

  Choices <- as.character(a)

  ui <- fluidPage(
    fluidRow(
      selectInput(inputId = "numfields", label = "Select Entries", choices = Choices, multiple = TRUE, selectize = TRUE),
      conditionalPanel(
          condition = "count(input$numfields) >= 1",
          textInput(inputId = "field1", label = "First One", value = "")
        ),
      conditionalPanel(
        condition = "count(input$numfields) >= 2",
        textInput(inputId = "field2", label = "Second One", value = "")
      ),
      conditionalPanel(
        condition = "count(input$numfields) >= 3",
        textInput(inputId = "field3", label = "Third One", value = "")
      )
      )
    )

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

  shinyApp(ui=ui, server=server)

另外，在相关的注释中，Shiny 自动默认没有为 selectInput 字段选择任何条目，其中 multiple = TRUE。有没有办法让它像 multiple = FALSE 一样选择第一个条目？

感谢您的帮助，谢谢。

Answer 1

这里是通过服务器的另一种解决方案。 显而易见的解决方案是renderUI()，但如果你想使用condtionalPanel()：

a <- c("A","B","C")

Choices <- as.character(a)

ui <- fluidPage(
  fluidRow(
    selectInput(inputId = "numfields", label = "Select Entries", choices = Choices, multiple = TRUE, selectize = TRUE),
    conditionalPanel(
      condition = "output.check > 0",
      textInput(inputId = "field1", label = "First One", value = "")
    ),
    conditionalPanel(
      condition = "output.check >= 2",
      textInput(inputId = "field2", label = "Second One", value = "")
    ),
    conditionalPanel(
      condition = "output.check >= 3",
      textInput(inputId = "field3", label = "Third One", value = "")
    )
  )
)

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

  output$check <- reactive({
    length(input$numfields)
  })

  outputOptions(output, 'check', suspendWhenHidden=FALSE)    
}

shinyApp(ui=ui, server=server)

Answer 2

您可以使用selected = 参数在selectInput() 中设置默认选择：

selectInput(inputId = "numfields", 
            label = "Select Entries", 
            choices = Choices, 
            multiple = TRUE, 
            selectize = TRUE, 
            selected = 'A')

conditionalPanel() 中的 condition = 参数采用解释为 JS 而不是 R 的文字。

要检查输入的“计数”，您应该使用input.numfields.length：

conditionalPanel(
  condition = "input.numfields.length >= 1",
  textInput(inputId = "field1", label = "First One", value = "")
)

下面是完整的ui：

ui <- fluidPage(
  fluidRow(
    selectInput(inputId = "numfields", 
                label = "Select Entries", 
                choices = Choices, 
                multiple = TRUE, 
                selectize = TRUE, 
                selected = 'A'),
    conditionalPanel(
      condition = "input.numfields.length >= 1",
      textInput(inputId = "field1", label = "First One", value = "")
    ),
    conditionalPanel(
      condition = "input.numfields.length >= 2",
      textInput(inputId = "field2", label = "Second One", value = "")
    ),
    conditionalPanel(
      condition = "input.numfields.length >= 3",
      textInput(inputId = "field3", label = "Third One", value = "")
    )
  )
)