如何防止每个UI交互重绘多次闪亮阴影？

Question

在我的闪亮应用程序中，我有一个日期范围输入和一组复选框。复选框的选择取决于输入$ dateRange。每当日期范围发生变化时，我都会遇到一个问题，即该绘图正在重绘两次。第一次重新绘制它将使用新的日期范围，但是旧的复选框选项。然后更新复选框选项并再次绘制该图。

是否有任何方法可以防止重绘多次，只有在所有其他UI元素更新后才能绘制它？

server.R代码片断

# Check boxes for variants in run 
    output$choose_variants <- renderUI({ 
    # Get the variants associated with the run 
    dat <- loadVariants(input$dateRange[1], input$dateRange[2]) 
    if(is.null(dat)) 
     return() 

    # Create the checkboxes and select them all by default 
    checkboxGroupInput("variants", "Variants", 
         choices = dat$variant, 
         selected = dat$variant) 
    }) 

    # Output the data 
    output$plot1 <- renderPlot({ 
    runLocations <- loadRunsBetweenDates(input$dateRange[1], input$dateRange[2], input$variants) 
    #ggplot() 
    }) 

ui.R代码片段

sidebarPanel(
    dateRangeInput('dateRange', 
     label = 'Date range', 
     start = Sys.Date(), end = Sys.Date() 
    ), 
    uiOutput("choose_variants") 
), 

Answer 1

由于input$variants总是变化时的日期范围滑块改变，你可以让你的情节只依赖于input$variants。

# Output the data 
    output$plot1 <- renderPlot({ 

    # outside of isolate statement, so this plot becomes dependent on its value. 
    input$variants 

    # put this in an isolate block, so it doesn´t trigger an invalidation. 
    isolate(runLocations <- loadRunsBetweenDates(input$dateRange[1], input$dateRange[2], input$variants)) 
    #ggplot() 
    }) 

希望这有助于！

编辑：另类，根据病情在评论

您可以创建一个反应，并让你的情节只依赖于如下：

loadedVariants <- reactive({ 
    loadVariants(input$dateRange[1], input$dateRange[2]) 
    }) 

# Output the data 
    output$plot1 <- renderPlot({ 

    # outside of isolate statement, so this plot becomes dependent on its value. 
    loadedVariants() 

    # put this in an isolate block, so it doesn´t trigger an invalidation. 
    isolate(runLocations <- loadRunsBetweenDates(input$dateRange[1], input$dateRange[2], input$variants)) 
    #ggplot() 
    })