如何通过在R Shiny中循环读取.csv文件来动态生成dataTableOutput？

Question

I have a function that generates "n" dataframes and saves it in a location as csv files and the function returns the file name of the saved CSVs.

I wish to take those csv files, read it using read.csv() and then display it on the UI using renderUI and renderDataTable()

While the code below has no syntax errors, but nothing is getting displayed on the screen.

Please suggest an appropriate method by which the tables generated in one part of the server.R can be used in output and display those data tables on the UI.

The code for the function is below :

Function

GenerateData <- function(){
   #********************************************************************
   # some sample data (originally, my data comes from an external souce)
   #--------------------------------------------------------------------
   a <- 1:10
   b<- 21:30
   c<-41:50
   sampleDat1 <- data.frame(a,b,c)
   sampleDat2<- data.frame(c,a,b,a)
   NumOfDataFrames <- 2
   #--------------------------------------------------------------------
   FilePath <- "D:/FolDerName/"
   FullPath<-WriteStatement <- NULL
   for(i in 1:NumOfDataFrames){

      FullPath[i]<-paste0(FilePath,"sampleDat",i,".csv")
      WriteStatement[i]<-paste0("write.csv(sampleDat",i,",file = '",FullPath[i],"')")
      eval(parse(text=WriteStatement[i]))
   }
   return(FullPath)

}

The UI.r

library(shiny)
shinyUI(

   fluidPage(

      # Application title

      navbarPage("Sample Data Display",
                 tabPanel("Data",
                          sidebarLayout(
                             sidebarPanel(
                                titlePanel("Sample"),
                                numericInput("sample1",label = "Some Label",value = 20),
                                numericInput("sample2",label = "Some Other Label",value = 20)
                             ),
                             mainPanel(
                                uiOutput("result")

                             )
                          )
                 )
      )
   )
)

The server.R

library(shiny)

GenerateData <- function(){
   #********************************************************************
   # already mentioned above, please copy the contents to server.R
   #--------------------------------------------------------------------


}
shinyServer(function(input, output,session) {
   dataSrc <- reactive({
      paths <- GenerateData()
      return(paths)
   })
   output$result <- renderUI({
      dataTab1<-NULL
      MyFilePath <- dataSrc()
      for (i in 1:length(MyFilePath)){
         dataTab1 <- read.csv(MyFilePath[i])
         # print(dataTab1)
         renderDataTable(dataTab1)
         dataTab1<-NULL

      }

   })
}
)

---

Answer 1

You can try

1) use list of df

GenerateData <- function(){
  #********************************************************************
  # some sample data (originally, my data comes from an external souce)
  #--------------------------------------------------------------------
  a <- 1:10
  b<- 21:30
  c<-41:50
  sampleDat1 <- data.frame(a,b,c)
  sampleDat2<- data.frame(c,a,b,a)
  NumOfDataFrames <- 2
  ls_df=list(sampleDat1,sampleDat2)
  names(ls_df)=c("sampleDat1","sampleDat2")
  #--------------------------------------------------------------------
  FilePath <- "C:\\12324\\files\\"
  FullPath=character()
  for(i in 1:length(ls_df)){
    FullPath[i]<-paste0(FilePath,names(ls_df)[i],".csv")
    write.csv(x=ls_df[[i]],file = FullPath[[i]])
  }
  return(FullPath)

}

2) Server.R( create dinamic ui and render DT in two step)

shinyServer(function(input, output,session) {
  dataSrc <- reactive({
    paths <- GenerateData()
    return(paths)
  })
  output$result <- renderUI({
    MyFilePath <- dataSrc()
    lapply(1:length(MyFilePath),function(i)dataTableOutput(paste0('tbl',i)))
  })
  observe({
    MyFilePath <- dataSrc()
    lapply(1:length(MyFilePath),function(i) output[[paste0("tbl",i)]]<-renderDataTable(read.csv(MyFilePath[i])))

  })
}
)