Shiny R Zip multiple PDFS for download - r

Question

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)
}
)
})

Answer 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"
)

Answer 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).