使用反应性创建的闪亮对象作为另一个反应性事件的输入。

Question

我的闪亮的应用程序使用DT库呈现动态数据框架。用户可以通过单击选择所需的行。选择行后，应用程序以数据帧的形式显示并下载转置行。但是，在这样做时(显示和下载)，我遇到了以下错误：

误差 Warning: Error in [.data.frame: undefined columns selected [No stack trace available]

以下是详细的步骤

1. 获取的数据(例如从某个网站)
2. 用户通过单击行来选择行，然后单击actionButton()将它们标记为“第一个组”
3. 用户清除前面的选择，并重复与“步骤-2”相同的步骤来创建第二个组。
4. clean()函数将转置数据帧(Rowname将变成列名)，然后根据用户选择的row.names()对数据框架进行子集。

可复制代码并添加注释

library(shiny)
library(DT)

temp_func <- function(){
  x <- mtcars
  y = x[,1]
  return(list(complete_df = as.data.frame(x), column1 = as.data.frame(y)))
}

clean <- function(df, g1, g2){
  x1 <- (mtcars)
  df_g1 <- subset(df, select = as.vector(g1))
  df_g2 <- subset(df, select = as.vector(g2))
  df_new <- cbind(df_g1, df_g2)
  return(as.data.frame(df_new))
}

# UI
ui <- shinyUI({
  fluidPage(
    actionButton("fetch", label = "Step1-Fetch data first"),
    DT::dataTableOutput("table"),br(),
    tags$h5("Selected for Group-1"), verbatimTextOutput("Group1"),br(),
    tags$h5("Selected for Group-2"),verbatimTextOutput("Group2"),hr(),br(),
    tags$h4("Follow Steps: "),
    actionButton("selG1", label = "Step-2: Mark as  Group-1"),
    actionButton("clear", label = "Step-3: Clear Selection"),
    actionButton("selG2", label = "Step-4: Mark as Group-2"),
    actionButton("cleanIt", "Step-5: Clean Dataframe"),
    DT::dataTableOutput("table2"),
    downloadButton("down", "Step-6: Download cleaned dataframe")
    )})

# Server
server <- Main_Server <- function(input,output,session){
  
  # Reactive Values
  values <- reactiveValues(table = NULL)
  group1 <- reactiveValues(Group1 = NULL)
  group2 <- reactiveValues(Group2 = NULL)
  clean_df <- reactiveValues(df = NULL)
  
  # fetchEvent (Consider temp_func() is fetching data from website)
  observeEvent(input$fetch, {values$table <- temp_func()})
  
  # Rendering table for display
  output$table <- renderDT({datatable(values$table$complete_df)})
  
  # Selection Event (Gorup1)
  observeEvent(input$selG1, {group1$Group1 <- rownames(values$table$complete_df[as.numeric(input$table_rows_selected),])})
  
  # Reset selections
  observeEvent(input$clear, {output$table <- renderDT({datatable(values$table$complete_df)})})
  
  # Selection Event (Gorup1)
  observeEvent(input$selG2, {group2$Group2 <- rownames(values$table$complete_df[as.numeric(input$table_rows_selected),])})
  
  # Print Events
  output$Group1 <- renderPrint({group1$Group1})
  output$Group2 <- renderPrint({group2$Group2})
  
  # observeEvent
  observeEvent(input$cleanIt, {clean_df$df <- clean(values$table$complete_df, group1$Group1, group2$Group2)
  })
  
  # Rendering table for display
  output$table2 <- renderDT({datatable(clean_df$df$df_new)})
  
   # Combined Download
  output$down <- downloadHandler(
    filename = function() { "File.csv"},
    content = function(file) {write.csv(clean_df$df$df_new, file)})
  
}

# Run-app
shinyApp(ui, server)

Answer 1

您的子设置是错误的；g1和g2是行名，但是您在subset中使用了它，它需要列名(因此您得到了错误消息)。因此，我更改了clean函数。由于您没有堆栈跟踪，所以您的错误消息并不能提供很好的信息。如果您想获得堆栈跟踪，应该在RStudio中使用闪亮的App (参见6.2.1末尾的这里 )。用这个，我得到了

Warnung: Error in [.data.frame: undefined columns selected
  78: stop
  77: [.data.frame
  75: subset.data.frame
  73: clean [C:\Users\jhage\Documents\Programmierung\Shiny_tests\app_2\shinytest7/app.R#12]
  72: observeEventHandler [C:\Users\jhage\Documents\Programmierung\Shiny_tests\app_2\shinytest7/app.R#63]
   1: runApp

所以更容易调试。

修正后的代码：

library(shiny)
library(DT)

temp_func <- function(){
  x <- mtcars
  y = x[,1]
  return(list(complete_df = as.data.frame(x), column1 = as.data.frame(y)))
}

clean <- function(df, g1, g2){
  df_selection <- df[c(which(rownames(df) == g1), which(rownames(df) == g2)),  ]
  df_new <- t(df_selection)
  return(as.data.frame(df_new))
}

# UI
ui <- shinyUI({
  fluidPage(
    actionButton("fetch", label = "Step1-Fetch data first"),
    DT::dataTableOutput("table"),br(),
    tags$h5("Selected for Group-1"), verbatimTextOutput("Group1"),br(),
    tags$h5("Selected for Group-2"),verbatimTextOutput("Group2"),hr(),br(),
    tags$h4("Follow Steps: "),
    actionButton("selG1", label = "Step-2: Mark as  Group-1"),
    actionButton("clear", label = "Step-3: Clear Selection"),
    actionButton("selG2", label = "Step-4: Mark as Group-2"),
    actionButton("cleanIt", "Step-5: Clean Dataframe"),
    DT::dataTableOutput("table2"),
    downloadButton("down", "Step-6: Download cleaned dataframe")
  )})

# Server
server <- Main_Server <- function(input,output,session){
  
  # Reactive Values
  values <- reactiveValues(table = NULL)
  group1 <- reactiveValues(Group1 = NULL)
  group2 <- reactiveValues(Group2 = NULL)
  clean_df <- reactiveValues(df = NULL)
  
  # fetchEvent (Consider temp_func() is fetching data from website)
  observeEvent(input$fetch, {values$table <- temp_func()})
  
  # Rendering table for display
  output$table <- renderDT({datatable(values$table$complete_df)})
  
  # Selection Event (Gorup1)
  observeEvent(input$selG1, {group1$Group1 <- rownames(values$table$complete_df[as.numeric(input$table_rows_selected),])})
  
  # Reset selections
  observeEvent(input$clear, {output$table <- renderDT({datatable(values$table$complete_df)})})
  
  # Selection Event (Gorup1)
  observeEvent(input$selG2, {group2$Group2 <- rownames(values$table$complete_df[as.numeric(input$table_rows_selected),])})
  
  # Print Events
  output$Group1 <- renderPrint({group1$Group1})
  output$Group2 <- renderPrint({group2$Group2})
  
  # observeEvent
  observeEvent(input$cleanIt, {clean_df$df <- clean(values$table$complete_df, group1$Group1, group2$Group2)
  })
  
  # Rendering table for display
  output$table2 <- renderDT({datatable(clean_df$df$df_new)})
  
  # Combined Download
  output$down <- downloadHandler(
    filename = function() { "File.csv"},
    content = function(file) {write.csv(clean_df$df$df_new, file)})
  
}

# Run-app
shinyApp(ui, server)

顺便看一看selection参数的datatable，您可以设置它，只有一行可以选择，然后您不需要在您的应用程序中的“撤消”按钮。