在Shiny中上传多个文件，处理文件，查找结果并返回下载 [英] Uploading multiple files in Shiny, process the files, rbind the results and return a download

问题描述

我需要上传多个csv文件(虚拟多个文件)，并对每个文件进行一些操作，然后将结果数据帧合并为一个数据帧，然后将输出下载为csv文件.我的原始R代码可以工作，但是我需要将其放到发亮的位置以便自动执行该过程，但是以某种方式，当我上传两个文件时，出现了此错误:下标超出范围".帮助将不胜感激.这是我原始的原始R代码，可以正常工作:

I need to upload multiple csv files (dummy multiple files) and apply some operations to each of the files, and then merge the resultant dataframes into one dataframe and download the output as csv file. My raw R code works but I need to put it on shiny in order to automate the process, but somehow when I uploaded two files, I got this error: "subscript out of bounds". Help will be appreciated. This is my original raw R Code that worked:

 files = list.files("G:/JSON to CSV/merge")
 numfiles = nrow(inFile)
 kata_csv1 = list()
 for (i in 1:numfiles)
 {
   kata_csv = function(y){
   JSON_csv = read.csv(y, header = TRUE)
   lastrow = nrow(JSON_csv)
   shift = function(x, n){
    c(x[-(seq(n))], rep(NA, n))
    }
  JSON_csv$companyID1 = shift(JSON_csv$companyID1, 1)
  JSON_csv = JSON_csv[-lastrow, ]
  JSON_csv 
  }
 kata_csv1[[i]] = kata_csv(files[i])
 }

 myMergedData = do.call(rbind, kata_csv1)
 write.csv(myMergedData, "myMergedData.csv", row.names=FALSE)

这是我的Shiny代码不起作用:

Here is my Shiny code that did not work:

UI.R:

  ui <- fluidPage(
   fluidPage(
     titlePanel("MY CSV FILES MERGER"),
     sidebarLayout(
       sidebarPanel(
         fileInput("file1",
              "Choose CSV files from directory",
              multiple = TRUE,
              accept=c('text/csv', 
                       'text/comma-separated-values,text/plain', 
                       '.csv')),
         downloadButton('downloadData', 'Download')
       ),
       mainPanel(
         tableOutput('contents')
       )
     )
   )
 )

Server.R:

 library(shiny)
 library(dplyr)
 function(input, output) {
   getData <- reactive({
     inFile <- input$file1
     if (is.null(inFile)){
     return(NULL)
     } else {
  numfiles = length(inFile) 
  kata_csv1 = list()
  for (i in 1:numfiles)
  {

      JSON_csv = read.csv(input$file1[[i, 'datapath']], header = TRUE)
      lastrow = nrow(JSON_csv)
      shift = function(x, n){
        c(x[-(seq(n))], rep(NA, n))
      }
      JSON_csv$companyID1 = shift(JSON_csv$companyID1, 1)
      kata_csv1[[i]] = JSON_csv[-lastrow, ]

    }
    do.call(rbind, kata_csv1)
   }
   })
   output$contents <- renderTable( 
   getData() 
   )
   output$downloadData <- downloadHandler(
    filename = function() { 
    paste("data-", Sys.Date(), ".csv", sep="")
   },
   content = function(file) { 
   write.csv(getData(), file, row.names=FALSE)   
  })
  }

推荐答案

该错误是因为要计算为numfiles = length(inFile)的numfiles为您提供inFile数据框中的列数.相反，您必须使用numfiles = nrow(inFile)，因为数据框中的行数为您提供了已上传的文件数.

The error is because the numfiles that you are calculating as numfiles = length(inFile) gives you the number of column in your inFile dataframe. You'll instead have to use numfiles = nrow(inFile) as the number of rows in the dataframe gives you the number of files that you have uploaded.

: 对我有用的代码是:

: The code that is working for me is:

 library(shiny)
  library(dplyr)
 server <-  function(input, output) {
    getData <- reactive({
      inFile <- input$file1
      if (is.null(inFile)){
        return(NULL)
      }else {
        # browser()
        numfiles = nrow(inFile) 
        kata_csv1 = list()


        for (i in 1:numfiles)
        {

          JSON_csv = read.csv(input$file1[[i, 'datapath']], header = TRUE)
          lastrow = nrow(JSON_csv)
          shift = function(x, n){
            c(x[-(seq(n))], rep(NA, n))
          }
          JSON_csv$companyID1 = shift(JSON_csv$companyID1, 1)
          kata_csv1[[i]] = JSON_csv[-lastrow, ]

        }
        # browser()
        do.call(rbind, kata_csv1)
      }
    })
    output$contents <- renderTable( 
      getData() 
    )
    output$downloadData <- downloadHandler(
      filename = function() { 
        paste("data-", Sys.Date(), ".csv", sep="")
      },
      content = function(file) { 
        write.csv(getData(), file, row.names=FALSE)   
      })
  }

 shinyApp(ui = ui, server = server)

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