闪亮的应用程序 - 在 if-then 语句中嵌入反应式表达式

Question

我很难在 Shiny Apps 中使用反应式表达。我正在从滑块输入创建一个饼图。这一切都很好，但是，标签重叠。为了避免这种情况，当输入为零时，我想要标签“”。困难在于我无法在 if-then 语句中嵌入反应式表达式。

这是一个 MWE...

文件“ui.R”...

library(shiny)

shinyUI(fluidPage(

  titlePanel("Exposure to English calculator"),

  sidebarLayout(
    sidebarPanel(

      h3("Sleeping"),

      sliderInput("sleep", "How long does your child sleep every day?",
                               min=0, max=15, value=0, step = 0.5),

    h3("School"),
    sliderInput("school", "How long does your child spend in school?",
                min = 0, max = 50, value=0, step = 0.5)
    ),

    mainPanel(
      plotOutput("plot")
    )



  )
))

文件服务器.R...

library(shiny)

values <- c(1,2)

# Define server logic for slider examples
shinyServer(function(input, output) {


  total_sleep <- reactive({7*input$sleep})

  pieLabels<-c("sleep", "school", "other")

  if(total_sleep() == 0) {
    pieLabels[1] <- ""
  }

  output$plot <- renderPlot({ 

    pie(c(total_sleep(), input$school, 50),
        labels = pieLabels,
        col = c("deepskyblue", "orange"),
        height = 1500
    )

  })


})

编译由于“if”表达式而崩溃，即使我在它后面加上了括号，以表明它是从反应式表达式派生的。

提前致谢。

Answer 1

您可以将所有total_sleep 代码和条件语句放在renderPlot 函数中：

library(shiny)

app <- shinyApp(
  ui = shinyUI(fluidPage(
    titlePanel("Exposure to English calculator"),
    sidebarLayout(
      sidebarPanel(
        h3("Sleeping"),
        sliderInput("sleep", "How long does your child sleep every day?",
                    min=0, max=15, value=0, step = 0.5),
        h3("School"),
        sliderInput("school", "How long does your child spend in school?",
                    min = 0, max = 50, value=0, step = 0.5)
      ),
      mainPanel(
        plotOutput("plot")
      )
    )
  )),
  server = shinyServer(function(input, output) {
    output$plot <- renderPlot({ 
      total_sleep <- 7*input$sleep
      pieLabels<-c("sleep", "school", "other")
      if(total_sleep == 0) {
        pieLabels[1] <- ""
      }
      pie(c(total_sleep, input$school, 50),
          labels = pieLabels,
          col = c("deepskyblue", "orange")
      )
    })
  }))

runApp(app)

请注意，我从 pie 中删除了 height，因为该参数不存在并且会发出警告。