R 在不从0开始的闪亮应用程序中设置移动v_线

我有以下闪亮的应用程序，它允许您过滤图形的一部分，并允许您启动计数器：

library(shiny)


UI <- fluidPage(

  div(style="display:inline-block",numericInput("start_time", "Starting time:", 1, min = 1, max = 100)),
  div(style="display:inline-block",numericInput("stop_time", "Stop time:", 5, min = 1, max = 100)),

  actionButton("start_counter","Start the counter"),

  plotOutput("plot_timeseries", width = "500px", height = "300px"),
  plotOutput("plot_timeseries2", width = "500px", height = "300px")

)


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

  counter <- reactiveVal(1)
  action <- reactiveVal(FALSE)

  # When goButton is clicked, set action() from FALSE to TRUE or the other way around.
  observeEvent(input$start_counter,
               {
                 action(!action())
               })

  # Add an oberserver that invalidates every second, and increments the counter if action()==TRUE
  observe({ invalidateLater(1000, session)
    isolate({
      if(action())
      {
        # Add 1 to our counter
        counter(counter() + 1) 
      }
    })
  })

  pp <- eventReactive(c(input$start_time, input$stop_time, counter()), {
    ggplot(mtcars, aes(x=wt, y=mpg)) +
      geom_point(size=2, shape=23) +
      scale_x_continuous(limits = c(input$start_time, input$stop_time)) +
      geom_vline(xintercept = counter())
  })

  output$plot_timeseries <- renderPlot({

    pp()  

  })

  output$plot_timeseries2 <- renderPlot({

    ggplot(mtcars, aes(x=wt, y=mpg)) +
      geom_point(size=2, shape=23) +
      geom_vline(xintercept =  counter())

  })

}


shinyApp(ui = UI, server = Server)

---

关于我应该做什么来实现我的目标有什么想法吗？

正如错误所说，您只能在反应上下文中使用

input$start\u time

，即

reactive（）

或

observe（）

或类似的内容

最简单的方法是将

计数器（输入$start\u time）

移动到

observe（）

函数中，如下所示：

observe({
    counter(input$start_time)
})

---

与反应式表达式不同，观察者使用急切求值，这意味着当依赖项发生变化时，会立即重新执行。这意味着此代码块将在任何

renderPlot

函数之前立即运行并更新

计数器的值，并且每当
input$start\u time
的值发生变化时，它将立即运行。
这里是实现所需的一种方法。我修改了你的代码，只是在代码上写着
modified
或
ADDED
的地方

现在，我已将vline设置为在您按下重置按钮时移动到开始时间。只要开始时间改变，您也可以重置该行，如果这是您想要的行为。只需将
observeEvent
更改为：

  # ADDED - if start time changes, reset the counter.
  observeEvent(input$reset_counter,
               {
                 counter(input$start_time)
               })

希望这有帮助



库（闪亮）
图书馆（GG2）
用户界面
Error in .getReactiveEnvironment()$currentContext() : 
Operation not allowed without an active reactive context. (You tried to do 
something that can only be done from inside a reactive expression or observer.)

observe({
    counter(input$start_time)
})

  # ADDED - if start time changes, reset the counter.
  observeEvent(input$reset_counter,
               {
                 counter(input$start_time)
               })

library(shiny)
library(ggplot2)

UI <- fluidPage(

  div(style="display:inline-block",numericInput("start_time", "Starting time:", 1, min = 1, max = 100)),
  div(style="display:inline-block",numericInput("stop_time", "Stop time:", 5, min = 1, max = 100)),

  actionButton("start_counter","Start the counter"),
  actionButton("reset_counter","Reset the counter"), # ADDED


  plotOutput("plot_timeseries", width = "500px", height = "300px"),
  plotOutput("plot_timeseries2", width = "500px", height = "300px")

)


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

  counter <- reactiveVal(1)
  action <- reactiveVal(FALSE)

  # When goButton is clicked, set action() from FALSE to TRUE or the other way around.
  observeEvent(input$start_counter,
               {
                 action(!action())
               })

  # Add an oberserver that invalidates every second, and increments the counter if action()==TRUE
  observe({ invalidateLater(1000, session)
    isolate({
      if(action() & counter() < input$stop_time) # MODIFIED - stop at stop time.
      {
        # Add 1 to our counter
        counter(counter() + 1) 
      }
      else # ADDED - to stop the timer from running when we modify the start or stop time.
      {
        action(FALSE) 
      }
    })
  })

  # ADDED - if start time changes, reset the counter.
  observeEvent(input$reset_counter,
               {
                 counter(input$start_time)
               })

  pp <- eventReactive(c(input$start_time, input$stop_time, counter()), {
    ggplot(mtcars, aes(x=wt, y=mpg)) +
      geom_point(size=2, shape=23) +
      scale_x_continuous(limits = c(input$start_time, input$stop_time)) +
      geom_vline(xintercept = counter())
  })

  output$plot_timeseries <- renderPlot({

    pp()  

  })

  output$plot_timeseries2 <- renderPlot({

    ggplot(mtcars, aes(x=wt, y=mpg)) +
      geom_point(size=2, shape=23) +
      geom_vline(xintercept =  counter())

  })

}


shinyApp(ui = UI, server = Server)