根据Shiny R中的单选按钮显示滑块输入

Question

我如何使滑块（例如，将其称为“分割mtcars wt”）弹出以显示选项b单选按钮，然后将x除以选项b的aes（来自mtcars数据集的wt）以除以该值在下面的可复制示例中？然后，如果选择了选项单选按钮，请再次隐藏该滑块。我看过几个Stack溢出帖子，但它们没有帮助。我收到选项b的NULL输出错误。

library(shiny)
library(ggplot2)
options(warn=-1)

#ui.r
ui <- pageWithSidebar(
  headerPanel("many plots app"),

  sidebarPanel(
    sliderInput("width", "Plot Width (%)", min = 0, max = 100, value = 100), 
    sliderInput("height", "Plot Height (px)", min = 0, max = 800, value = 800),
    uiOutput("filter_plot")

  ),

  mainPanel(
    uiOutput("plot")
  )
)
#server.r
server <- function(input, output, session) {

  options(warn = -1) #This doesn't stop console warning to stop

  output$filter_plot<-renderUI({
    radioButtons("rd","Select Option",choices = c("a",
                                                  "b",
                 selected = "a"))
  })

output$plot <- renderUI({
    if(input$rd=="a"){
      output$plot1<- renderPlot({
        ggplot2::ggplot(mtcars, aes(mpg, cyl))+ geom_point()
      })
      plotOutput("plot1", width = paste0(input$width, "%"), height = input$height)
    }
    else if(input$rd=="b"){
      output$plot2<- renderPlot({
        ggplot2::ggplot(mtcars, aes(wt, qsec))+ geom_line()

      })
      plotOutput("plot2", width = paste0(input$width, "%"), height = input$height)
    }
  })
}
shinyApp(ui = ui, server = server)

谢谢你！

如果可以的话，请再帮一个忙，尽管我已经隐藏了它们，但为什么控制台中仍会发出警告。我的应用程序可以运行，但是警告在那里：

#Warning: Error in if: argument is of length zero
#  96: renderUI [C:/Users/YOU/Documents/DIRECTORY/xyz.R#443]
#  95: func
#  82: origRenderFunc
#  81: output$plot
#  1: runApp

Answer 1

从单选按钮输入中选择“ b”时，您可以使用conditionalPanel显示/隐藏sliderInput。

为了避免警告，您可以在req(input$rd)语句中使用if之前要求它。

让我知道这是否是您要记住的行为。

library(shiny)
library(ggplot2)
options(warn=-1)

#ui.r
ui <- pageWithSidebar(
  headerPanel("many plots app"),

  sidebarPanel(
    sliderInput("width", "Plot Width (%)", min = 0, max = 100, value = 100), 
    sliderInput("height", "Plot Height (px)", min = 0, max = 800, value = 800),
    uiOutput("filter_plot"),
    conditionalPanel(
      "input.rd == 'b'",
      sliderInput("sl_wt", "Divide Weight", min = 1, max = 10, value = 5)
    )
  ),

  mainPanel(
    uiOutput("plot")
  )
)
#server.r
server <- function(input, output, session) {

  options(warn = -1) #This doesn't stop console warning to stop

  output$filter_plot<-renderUI({
    radioButtons("rd","Select Option",choices = c("a",
                                                  "b",
                                                  selected = "a"))
  })

  output$plot1<- renderPlot({
    ggplot2::ggplot(mtcars, aes(mpg, cyl))+ geom_point()
  })

  output$plot2<- renderPlot({
    ggplot2::ggplot(mtcars, aes(wt/input$sl_wt, qsec))+ geom_line()
  })

  output$plot <- renderUI({
    req(input$rd)
    if(input$rd=="a"){
      plotOutput("plot1", width = paste0(input$width, "%"), height = input$height)
    }
    else if(input$rd=="b"){
      plotOutput("plot2", width = paste0(input$width, "%"), height = input$height)
    }
  })
}
shinyApp(ui = ui, server = server)