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r - R Shiny验证列号输入文件

问题描述

我正在复制 Shiny File Upload 应用程序的示例。如您所见，我为文件类型添加了验证功能。我还设置了固定的列名，因为我希望用户最多只能上传 5 列的日期。

现在，当用户上传的文件的列数超过允许的列数时，将显示 R 消息： more columns than column names.

我想要一个 validate/require 函数来检查列数并显示更用户友好的消息。我的想法是使用 validate 函数，(ncol(input$file1)<=5)==TRUE但不知何故，这似乎不起作用。任何人都知道如何检查输入文件上的列数并更改显示的用户消息？（如果它可以用 Shinyalert 完成，那就太棒了！）。

最后，我还在努力找出如何将表格包装在我以后可以回忆的反应性数据框周围。

提前致谢！

library(shiny)
library(tools)

ui <- fluidPage(

  # App title ----
  titlePanel("Uploading Files"),

  # Sidebar layout with input and output definitions ----
  sidebarLayout(

    # Sidebar panel for inputs ----
    sidebarPanel(

      # Input: Select a file ----
      fileInput("file1", "Choose CSV File",
                multiple = FALSE,
                accept = c("text/csv",
                           "text/comma-separated-values,
                           text/plain",
                           ".csv")),

      # Horizontal line ----
      tags$hr(),

      # Input: Select separator ----
      radioButtons("sep", "Separator",
                   choices = c(Comma = ",",
                               Semicolon = ";",
                               Tab = "\t"),
                   selected = ","),

      # Input: Select quotes ----
      radioButtons("quote", "Quote",
                   choices = c(None = "",
                               "Double Quote" = '"',
                               "Single Quote" = "'"),
                   selected = '"'),

      # Horizontal line ----
      tags$hr(),

      # Input: Select number of rows to display ----
      radioButtons("disp", "Display",
                   choices = c(Head = "head",
                               All = "all"),
                   selected = "head")

    ),

    # Main panel for displaying outputs ----
    mainPanel(

      # Output: Data file ----
      tableOutput("contents")

    )

  )
)

server <- function(input, output) {

  output$contents <- renderTable({

    # input$file1 will be NULL initially. After the user selects
    # and uploads a file, head of that data file by default,
    # or all rows if selected, will be shown.

    req(input$file1)

    # when reading semicolon separated files,
    # having a comma separator causes `read.csv` to error
    tryCatch(
      {
        df <- read.csv(input$file1$datapath,
                       header = F,
                       sep = input$sep,
                       quote = input$quote,
                       col.names = c("COL1","COL2","COL3","COL4","COL5"),
                       check.names = F)
      },

      validate(
        need(file_ext(input$file1$datapath) %in% c(
          'text/csv',
         'text/comma-separated-values',
          'text/tab-separated-values',
          'text/plain',
          'csv'
        ), "Data was not recognized. Please use a CSV file!")),

      error = function(e) {
        # return a safeError if a parsing error occurs
        stop(safeError(e))
      }
    )

    if(input$disp == "head") {
      return(head(df))
    }
    else {
      return(df)
    }

  })

}

shinyApp(ui,server)

标签： rshinyshinyalert

解决方案

我尝试构建一个示例程序，用户只能上传只有 5 列的 csv 数据集。您可以根据您的要求进行更改。

用户界面

library(shiny)
library(shinydashboard)
library(shinyjs)
library(shinyalert)


dashboardPage(
   dashboardHeader(title = "Basic dashboard"),
   dashboardSidebar(
      sidebarMenu(
         menuItem("Dashboard", tabName = "dashboard", icon = icon("dashboard"))
      )
   ),
   dashboardBody(
      useShinyalert(),
      tabItems(
         tabItem(tabName = "dashboard",
                 fluidRow(
                           column(3,

                                     fileInput("file1", "Choose CSV File",
                                               multiple = FALSE,
                                               accept = c("text/csv",
                                                          "text/comma-separated-values,
                                                            text/plain",
                                                          ".csv"))
                                  )

                        ),
                 fluidRow(
                    tableOutput("contents")
                        )
                 )
      )
   )
)

服务器.R

library(shiny)
library(shinydashboard)


shinyServer(function(input,output){

  output$contents <- renderTable({
    inFile <- input$file1

    if (is.null(inFile))
    {
      returnValue()
    }
    else
    {
      data<-read.csv(inFile$datapath)
      if(ncol(data)<5)
      {
        shinyalert("Column Error","Uploaded Data has less than 5 Col",type="error")
        returnValue()
      }
      else if(ncol(data)>5)
      {
        shinyalert("Column Error","Uploaded Data has more than 5 Col",type = "error")
        returnValue()
      }
      else
      {
        return(data)
      }
    }

  })

})

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