无法动态填充下拉菜单在R闪亮 [英] Cannot populate drop down menu dynamically in R shiny

问题描述

我试图使用R Shiny创建一个APP。我想上传数据（.csv文件）。然后，我想在下拉菜单中填充CSV文件中的列名称。我不能这样做。

I am trying to create an APP using R Shiny. I want to upload data (.csv file). Then I want to populate the column names in CSV file in a drop down menu. I am unable to do that.

请参考以下代码：

----服务器。 r -----

---- server.r -----

library(shiny)
options(shiny.maxRequestSize = 32*1024^2)


shinyServer(


function(input, output){ 

data <- reactive({
  file1 <- input$file
  if(is.null(file1)){return()} 
  read.table(file=file1$datapath,head=TRUE,sep=",")

})

output$sum <- renderTable({
  if(is.null(data())){return ()}
  summary(data())

})

output$table <- renderTable({
  if(is.null(data())){return ()}
  data()
})

# the following renderUI is used to dynamically generate the tabsets when the file is loaded. Until the file is loaded, app will not show the tabset.
output$tb <- renderUI({
  if(is.null(data()))
    h5("no file loaded")
  else
    tabsetPanel(tabPanel("Data", tableOutput("table")),tabPanel("Summary", tableOutput("sum")))
})

   output$col <- renderUI({

  selectInput("phenomena", "Select the Phenomena",  names(data))
  })

})  

----- ui.R -----

----- ui.R -----

 library(shiny)


 shinyUI(fluidPage(

 titlePanel("Hotspot Analysis of EnviroCar Data"),
 sidebarLayout(
 sidebarPanel(

  # uploading the file 
   fileInput("file","Upload *.csv file"), # fileinput() function is used to get the file upload contorl option

  uiOutput("col")


),

mainPanel(  uiOutput("tb") )

)

))

推荐答案

我想问题出在 server.R ：

selectInput("phenomena", "Select the Phenomena",  names(data))

这里，你使用没有括号的 data ，所以你实际获得的是函数的源代码 data ， names（data）是 NULL 。我想你所需要的是用 names（data（））替换名称（数据）。

Here, you're using data without parentheses so what you actually obtain is the source code of the function data, and names(data) is NULL. I think all you need is to replace names(data) by names(data()).

这篇关于无法动态填充下拉菜单在R闪亮的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！