问修复初始shinyr应用程序加载的selectInput错误

EN

plot_and_summary <- function(dat, col){
  summary <- dat %>% summarize_(mean = interp(~mean(x), x = as.name(col)),
                                sd = interp(~sd(x), x = as.name(col)))
  plot <- ggplot(dat, aes_string(x = col)) + geom_histogram()
  return(list(summary = summary, plot = plot))
} 


library(shiny)

# Define UI for application that draws a histogram
ui <- fluidPage(
  titlePanel(""),
  sidebarLayout(
    sidebarPanel(
      uiOutput("column_select"),
      submitButton("Submit")
    ),
    mainPanel(
      tableOutput("summary"),
      plotOutput("plot")
      )
  )

)

# Define server logic required to draw a histogram
server <- function(input, output){
  dat <- reactive({iris})


  output$column_select <- renderUI({selectInput("col", label = "select column", choices = as.list(names(dat())))})



  pas <- reactive({plot_and_summary(dat(), input$col)})
  output$plot <- renderPlot({pas()$plot})
  output$summary <- renderTable({pas()$summary})


}


shinyApp(ui = ui, server = server)