R 闪亮：仅在上传文件后显示按钮

我正在尝试闪亮，我喜欢它。我构建了一个小应用程序，学生上传一个csv文件，然后选择一个因变量和自变量，然后R计算一个线性回归。它很好用。我已上载至：

[如果需要，可以使用来测试它。“beer”是因变量，除“id”之外的其他变量是独立变量]

这是服务器。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))
    })   
  })

}) 

我的问题是：我想让“读取文件并选择变量后按”按钮的外观以成功上传为条件

我尝试使用此处包含的建议：

但我就是做不到

---

我感谢您的帮助。

此代码对我有效

用户界面

服务器.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))
    })   
  })


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

}) 

#server.R
图书馆（闪亮）
shinyServer（功能（输入、输出）{
filedata以下是基于Marat提供的所有建议的ui.R和server.R的最终版本

首先是ui.R

# ui.R

library(shiny)

shinyUI(fluidPage(
  titlePanel("Multiple Linear Regression with R/Shiny"),
  sidebarLayout(
    sidebarPanel(
      p("Please upload a CSV formatted file with your data."),
      fileInput('file1', label='Click button below to select the file in your computer.',
                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(
      p("Here's the output from your regression:"),
      verbatimTextOutput('contents')
    )
  )
))

和服务器.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$ui.action <- renderUI({
    if (is.null(filedata())) return()
    actionButton("action", "Run regression")
  })

  output$dependent <- renderUI({
    df <- filedata()
    if (is.null(df)) return(NULL)
    items=names(df)
    names(items)=items
    selectInput("dependent","Now 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","Also select ONE or MANY independent variables in the box below. You can change your selection several times:",items,multiple=TRUE)
  })


  output$contents <- renderPrint({
    if (is.null(input$action)) return()
    if (input$action==0) return()
    isolate({
      df <- filedata()
      if (is.null(df)) return(NULL)
      fmla <- as.formula(paste(input$dependent," ~ ",paste(input$independents,collapse="+")))
      summary(lm(fmla,data=df))
    })
  })


}) 

#server.R
图书馆（闪亮）
shinyServer（功能（输入、输出）{
filedata谢谢你，Marat。我尝试了你的解决方案。它使按钮看起来不一样…这很好。但上传文件后它不会出现。我估计你的服务器。R文件中有一行检查文件上传是否成功。@user23438，我无法使用
条件面板
获得解决方案，因为我不知道如何正确设置
条件
。我编辑了答案，该答案现在基于uiOutput。再次感谢Marat为您提供的时间。您的新解决方案使我更接近解决方案。现在按钮出现在正确的时刻，但它会对我的输出$contents产生问题。在此之前，我将本节中的代码包装为“隔离（{}）”这是由input$action激活的。现在input$action不见了，因为按钮不见了。我可以去掉isolate，但在选择正确的变量之前它会打印垃圾。如果要防止在output$contents中过早输出，可以在那里插入两个检查：替换
input$action
为
If（is.null（输入$action））return（）
和
if（输入$action==0）return（）
# ui.R

library(shiny)

shinyUI(fluidPage(
  titlePanel("Multiple Linear Regression with R/Shiny"),
  sidebarLayout(
    sidebarPanel(
      p("Please upload a CSV formatted file with your data."),
      fileInput('file1', label='Click button below to select the file in your computer.',
                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(
      p("Here's the output from your regression:"),
      verbatimTextOutput('contents')
    )
  )
))

# server.R

library(shiny)

shinyServer(function(input, output) {

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

  output$ui.action <- renderUI({
    if (is.null(filedata())) return()
    actionButton("action", "Run regression")
  })

  output$dependent <- renderUI({
    df <- filedata()
    if (is.null(df)) return(NULL)
    items=names(df)
    names(items)=items
    selectInput("dependent","Now 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","Also select ONE or MANY independent variables in the box below. You can change your selection several times:",items,multiple=TRUE)
  })


  output$contents <- renderPrint({
    if (is.null(input$action)) return()
    if (input$action==0) return()
    isolate({
      df <- filedata()
      if (is.null(df)) return(NULL)
      fmla <- as.formula(paste(input$dependent," ~ ",paste(input$independents,collapse="+")))
      summary(lm(fmla,data=df))
    })
  })


})