Shiny R Zip multiple PDFS for download

问题:

I am sorry if this too simple... I need to zip a number of generated pdfs for uses to download. I tried to use Zip function, but failed with error:

Warning: running command '"zip" -r9X "pdfs.zip" "plot_1.pdf" "plot_2.pdf" "plot_3.pdf" "plot_4.pdf" "plot_5.pdf" ' had status 127
Error opening file: 2
Error reading: 6

Below is my code and any suggestions are welcomed (based on shiny app : disable downloadbutton) :

UI.R

library(shiny)

shinyUI(fluidPage(
  singleton(tags$head(HTML(
'
  <script type="text/javascript">
    $(document).ready(function() {
      // disable download at startup. data_file is the id of the downloadButton
      $("#data_file").attr("disabled", "true").attr("onclick", "return false;");

      Shiny.addCustomMessageHandler("download_ready", function(message) {
        $("#data_file").removeAttr("disabled").removeAttr("onclick").html(
          "<i class=\\"fa fa-download\\"></i>Download " + message.fileSize + " ");
      });
    })
  </script>
'
))),
  tabsetPanel(
    tabPanel('Data download example',
      actionButton("start_proc", h5("Click to start processing data")),
      hr(),

      downloadButton("data_file"),
      helpText("Download will be available once the processing is completed.")
    )
  )
))

Server UI.R

library(shiny)

get_a_pdf_plot <- function(my_i){
      pdf(paste("plot_", my_i, sep=""))
      plot(1:my_i*5, 1:my_i*5,
           xlim = c(1, my_i*5),
           ylim = c(1, my_i*5),
           main = paste("1:", my_i, sep = ""))
      dev.off()
}


shinyServer(function(input, output, session) {

  observe({
    if (input$start_proc > 0) {
      Sys.sleep(2)
      session$sendCustomMessage("download_ready", list(fileSize= "Ready"))
    }
  })

  output$data_file <- downloadHandler(
       filename = 'pdfs.zip',
       content = function(fname) {
        fs <- c()
        tmpdir <- tempdir()
        setwd(tempdir())
        print (tempdir())

        for (i in c(1,2,3,4,5)) {
          path <- paste("plot_", i, ".pdf", sep="")
          fs <- c(fs, path)
          get_a_pdf_plot(i)
        }
        print (fs)
        zip(zipfile="pdfs.zip", files=fs)
       }
  )
})

回答1:

In get_a_pdf_plot you have ommitted the .pdf

get_a_pdf_plot <- function(my_i){
  pdf(paste("plot_", my_i,".pdf", sep=""))
  plot(1:my_i*5, 1:my_i*5,
       xlim = c(1, my_i*5),
       ylim = c(1, my_i*5),
       main = paste("1:", my_i, sep = ""))
  dev.off()
}

In your downloadHandler your need to prompt shiny on the download type:

 output$data_file <- downloadHandler(
    filename = 'pdfs.zip',
    content = function(fname) {
      fs <- c()
      tmpdir <- tempdir()
      setwd(tempdir())
      print (tempdir())

      for (i in c(1,2,3,4,5)) {
        path <- paste("plot_", i, ".pdf", sep="")
        fs <- c(fs, path)
        get_a_pdf_plot(i)
      }
      print (fs)
      zip(zipfile="pdfs.zip", files=fs)
    },
    contentType = "application/zip"
  )

回答2:

This gist helped me setup the export. It runs out of the box on a Mac. Windows required downloading Rtools and pointing to the zip in Rtools (from this question). I've not had problems yet.

Sys.setenv(R_CMDZIP = 'C:/Rtools/bin/zip')

The ?zip documentation mentions "On Windows, the default relies on a zip program (for example that from Rtools". If you point to a zip executable for your favorite zip program I'm sure it'll work similarly (if you don't want to download Rtools).