Question

我有一个双头闪亮的滑块输入，如下所示：

sliderInput(inputId = "years",
                             label="Choose base year and target year",
                             min = 2015,
                             max = 2060,
                             value = c(2015,2060),
                             step = 1,
                             sep = ""
                 )

用户上载值后，我想将滑块的下端固定为某个值；上端应仍可移动。我尝试通过使用updateSliderInput函数并仅为“值”属性提供一个值来实现这一点（因此，该滑块应成为常规的单端滑块）：

  observeEvent(upload(), {
    updateSliderInput(session, inputId = "years", min = base_year(), max = 2060, value = 2060)
  })

但是，这行不通；滑块仍然是双端的，并且两个手柄都设置为2060。如何将双端滑块转换为常规滑块？

亲切的问候，

Requin

Answer 1

这是另一个更接近您的问题的解决方案，只需按一下按钮即可触发一次：

library(shiny)

ui <- fluidPage(
  uiOutput("Slider_UI"),
  conditionalPanel("input.fixLower == 0", {actionButton("fixLower", "Fix lower range")})
)

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

  fixedLower <- reactiveVal()

  observeEvent(input$fixLower, {
    fixedLower(min(isolate({input$years})))
  }, once = TRUE)

  output$Slider_UI <- renderUI({
    if(is.null(fixedLower())){
      sliderInput(inputId = "years",
                  label="Choose base year and target year",
                  min = 2015,
                  max = 2060,
                  value = c(2015, 2060),
                  step = 1,
                  sep = ""
      )
    } else {
      sliderInput(inputId = "years",
                  label="Choose base year and target year",
                  min = fixedLower(),
                  max = 2060,
                  value = fixedLower(),
                  step = 1,
                  sep = ""
      )
    }
  })

}

shinyApp(ui = ui, server = server)

如@DSGym所建议，以下是使用renderUI的示例：

library(shiny)

ui <- fluidPage(
  radioButtons(inputId="type_select", label="Select slider type", choices = list("Standard slider", "Range slider")),
  uiOutput("Slider_UI")
)

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

  output$Slider_UI <- renderUI({
    req(input$type_select)

    if(input$type_select == "Range slider"){
      presetValues <- c(2015, 2060)
    } else {
      presetValues <- 2060
    }

    sliderInput(inputId = "years",
                label="Choose base year and target year",
                min = 2015,
                max = 2060,
                value = presetValues,
                step = 1,
                sep = ""
    )
  })

}

shinyApp(ui = ui, server = server)

闪亮的updateSliderInput：将双端滑块转换为单端滑块

1 个答案: