r - Shiny :仅在文件上传后显示按钮

Question

我正在尝试Shiny，我喜欢它。我构建了一个小应用程序，学生可以在其中上传一个csv文件，然后选择一个因变量和自变量，然后R计算线性回归。它工作正常。我将其上传到：

http://carlosq.shinyapps.io/Regresion

[如果需要，可以使用this file对其进行测试。 “啤酒”是因变量，除“ id”之外的其余变量都是自变量]

这是server.R：

# server.R
library(shiny)

shinyServer(function(input, output) {

  filedata <- reactive({
    infile <- input$file1
    if (is.null(infile)){
      return(NULL)      
    }
    read.csv(infile$datapath)
  })

  output$dependent <- renderUI({
    df <- filedata()
    if (is.null(df)) return(NULL)
    items=names(df)
    names(items)=items
    selectInput("dependent","Select ONE variable as dependent variable from:",items)
  })


  output$independents <- renderUI({
    df <- filedata()
    if (is.null(df)) return(NULL)
    items=names(df)
    names(items)=items
    selectInput("independents","Select ONE or MANY independent variables from:",items,multiple=TRUE)
  })


  output$contents <- renderPrint({
    input$action
    isolate({   
      df <- filedata()
      if (is.null(df)) return(NULL)
      fmla <- as.formula(paste(input$dependent," ~ ",paste(input$independents,collapse="+")))
      summary(lm(fmla,data=df))
    })   
  })

}) 

这是ui.R：

# ui.R
library(shiny)

shinyUI(fluidPage(
  titlePanel("Multiple Linear Regression"),
  sidebarLayout(
    sidebarPanel(
      fileInput('file1', 'Choose CSV File',
                accept=c('text/csv', 
                         'text/comma-separated-values,text/plain', 
                         '.csv')),

      tags$hr(),
      uiOutput("dependent"),
      uiOutput("independents"),
      tags$hr(),
      actionButton("action", "Press after reading file and selecting variables")

    ),
    mainPanel(
      verbatimTextOutput('contents')
    )
  )
))

我的问题是：我要使按钮“在读取文件并选择变量后按”的外观以成功上传为条件。

我尝试使用此处包含的建议：

Make conditionalPanel depend on files uploaded with fileInput

但是我只是无法使其工作。

我感谢您的帮助。

Answer 1

这段代码对我有用

用户界面

 # ui.R
library(shiny)

shinyUI(fluidPage(
  titlePanel("Multiple Linear Regression"),
  sidebarLayout(
    sidebarPanel(
      fileInput('file1', 'Choose CSV File',
                accept=c('text/csv', 
                         'text/comma-separated-values,text/plain', 
                         '.csv')),

      tags$hr(),
      uiOutput("dependent"),
      uiOutput("independents"),
      tags$hr(),
      uiOutput('ui.action') # instead of conditionalPanel
    ),
    mainPanel(
      verbatimTextOutput('contents')
    )
  )
))

服务器

# server.R
library(shiny)

shinyServer(function(input, output) {

  filedata <- reactive({
    infile <- input$file1
    if (is.null(infile)){
      return(NULL)      
    }
    read.csv(infile$datapath)
  })

  output$dependent <- renderUI({
    df <- filedata()
    if (is.null(df)) return(NULL)
    items=names(df)
    names(items)=items
    selectInput("dependent","Select ONE variable as dependent variable from:",items)
  })


  output$independents <- renderUI({
    df <- filedata()
    if (is.null(df)) return(NULL)
    items=names(df)
    names(items)=items
    selectInput("independents","Select ONE or MANY independent variables from:",items,multiple=TRUE)
  })


  output$contents <- renderPrint({
    input$action
    isolate({   
      df <- filedata()
      if (is.null(df)) return(NULL)
      fmla <- as.formula(paste(input$dependent," ~ ",paste(input$independents,collapse="+")))
      summary(lm(fmla,data=df))
    })   
  })


  output$ui.action <- renderUI({
    if (is.null(input$file1)) return()
    actionButton("action", "Press after reading file and selecting variables")
  })

})