闪亮：仅在文件上传后显示按钮

Question

我正在试用 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，然后选择因变量和自变量，然后 R 计算线性回归。它工作正常。我把它上传到：

http://carlosq.shinyapps.io/Regresion

[你可以用this file测试一下。 "beer" 是因变量，除 "id" 之外的其余变量是自变量]

这里是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))
    })   
  })

})

这里是 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：我想让按钮的外观 "Press After Reading File and selecting variables " 以上传成功为条件。

我已尝试使用此处包含的建议：

Make conditionalPanel depend on files uploaded with fileInput

但我就是做不到。

我很感激任何帮助。

Answer 1

这段代码对我有用

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(),
      uiOutput('ui.action') # instead of conditionalPanel
    ),
    mainPanel(
      verbatimTextOutput('contents')
    )
  )
))

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))
    })   
  })


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

})

Answer 2

根据 Marat 提供的所有建议，working ShinyApp 和 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$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))
    })
  })


})

再次感谢马拉特的帮助。

闪亮：仅在文件上传后显示按钮

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