Shiny 应用程序出错：找不到功能

Question

这是一个闪亮的应用程序，可根据用户输入输出图表和表格。一旦用户单击“开始”，值就会更新。

我犹豫不决是对每个变量使用“eventReactive”，如 pt_class、arm、freq 等，还是在开始时使用“observeEvent”来捕获“go”的点击一次。我选择了后者，但我无法理解为什么会出现此错误：

Warning: Error in freq: could not find function "freq"
  72: observeEventHandler [~/ShinyApp/app.R#108]
   1: runApp 

正如您在下面的代码中看到的，我已经定义了“freq”...... 提前致歉，因为该应用程序依赖于其他 python 脚本，但如果需要诊断问题，我很乐意分享它们。

ui <- navbarPage(numericInput(inputId = "vl",
                             "Viral load threshold (copies/mL):", value = 1000, min=50, max=10000000),
                             radioButtons("one_or_duration", "Duration at or above viral load threshold:",
                                          c("A single measurement","Multiple measurements")),
                             radioButtons("pt_class", "Time of treatment:",
                             c("All study participants","Early treated participants","Chronic treated participants")),
                             br(),
                             radioButtons("nnrti", "Include participants on NNRTIs?",
                                          c("No, exclude participants on NNRTIs","Yes, include participants on NNRTIs")),
                             radioButtons("freq", "Expected frequency of post-treatment controllers:",
                                          c("Same frequency as observed by authors","Input expected frequency")),
                             actionButton(inputId="go",label="Go!"),
                             
                             mainPanel(
                             plotOutput(outputId = "graph"), DT::dataTableOutput(outputId="table")))

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

  observeEvent(input$go,{

  one_or_duration <- 
              if(input$one_or_duration == "A single measurement"){
              "single"}
              else if(input$one_or_duration == "Multiple measurements"){
              "multiple"}
  
  nnrti <- 
    if(input$nnrti == "Yes, include participants on NNRTIs"){
      "yes"}
    else if(input$nnrti == "No, exclude participants on NNRTIs"){
      "no"}
  
  freq <- 
    if(input$freq == "Same frequency as observed by authors"){
      "same"}
    else if(input$freq == "Input expected frequency"){
      "diff"}
  
  pt_class <- 
    if(input$pt_class == "All study participants"){
      "all"}
    else if(input$pt_class == "Early treated participants"){
      "early"}
    else if(input$pt_class == "Chronic treated participants"){
      "chronic"}
 
  ptcs_plus_ncs <- 
    if (freq() == "same"){do_this
}
        
  
})}

shinyApp(ui = ui, server = server)

Answer 1

在当前的形式中，我无法运行您的代码，因此我无法更深入地研究问题。

然而，乍一看，R 会遇到上述错误，因为您没有将

freq

定义为反应式，但仍将其称为

freq()

，这会导致 R 查找名为

freq

的函数。这同样适用于其他一些变量，例如

pt_class()

、

one_or_duration()

、

nnrti()

、

arm()

等

带有

observeEvent(input$go,{

的部分有点问题，看来你不需要 if 子句。而是在 UI 输入值中使用命名向量。例如代替

radioButtons("one_or_duration", "Duration at or above viral load threshold:",
             c("A single measurement","Multiple measurements"))

写

radioButtons("one_or_duration", "Duration at or above viral load threshold:",
             c("A single measurement" = "single",
               "Multiple measurements" = "multiple"))

然后你就不需要这部分了

one_or_duration <- 
              if(input$one_or_duration == "A single measurement"){
              "single"}
              else if(input$one_or_duration == "Multiple measurements"){
              "multiple"}

后来，不再使用

one_or_duration()

（它不是反应式的，不能通过添加括号来调用），只需使用 input$one_or_duration 。顺便说一句，您不需要使输入变量具有反应性，因为它们已经是反应性的。

这肯定不能解决代码的所有问题，但它可能是一个开始。