Download multi-plots in PDF

server.r

library(shiny)
library(ggplot2)
shinyServer(function(input,output)({
  

  # downloadHandler contains 2 arguments as functions, namely filename, content
  output$down <- downloadHandler(
    filename =  function() {
      paste("multiplot.pdf")
    },
    # content is a function with argument file. content writes the plot to the device
    content = function(file) {
      pdf(file) # open the pdf device
      
      ## Plot multiple using par for multi-plots
      par(mfrow=c(1,2))
      print(ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() + labs("mtcars plot1"))
      print(ggplot(mtcars, aes(x=factor(am), y=mpg)) + geom_boxplot() + labs("mtcars plot2"))
      ## Uncomment the below if you want to experiment with base plot system
#       plot(mtcars$mpg, mtcars$cyl)
#       plot(mtcars$cyl, mtcars$hp)
      dev.off()  # turn the device off
    } 
  )
  
}))

ui.r

library(shiny)
shinyUI(fluidPage(
  titlePanel("Download PDF with multi plots in Shiny - an example"),
  sidebarLayout(
    sidebarPanel(
      downloadButton(outputId = "down", label = "Download the plot")
      ),
    mainPanel()
  )
  
))