R Shiny Download GGPLOT demo

server.r

library(shiny)
library(ggplot2)
shinyServer(function(input,output)({
  # x contains all the observations of the x variable selected by the user. X is a reactive function
  x <- reactive({
    iris[,as.numeric(input$var1)]
  })
  # x contains all the observations of the y variable selected by the user. Y is a reactive function
  y <- reactive({
    iris[,as.numeric(input$var2)]
    
  })
  # xl contains the x variable or column name of the iris dataset selected by the user
  xl <- reactive({
    names(iris[as.numeric(input$var1)])
    })
  # yl contains the y variable or column name of the iris dataset selected by the user
  yl <- reactive({
    names(iris[as.numeric(input$var2)])
  })
  
  # render the plot so could be used to display the plot in the mainPanel
  output$plot <- renderPlot({
    # plot(x=x(), y=y(), main = "iris dataset plot", xlab = xl(), ylab = yl())
    ggplot(iris, aes(x=x(), y=y())) + geom_point(shape=1) # ploting through GGPLOT
  })
  
  # downloadHandler contains 2 arguments as functions, namely filename, content
  output$down <- downloadHandler(
    filename =  function() {
      paste("iris", input$var3, sep=".")
    },
    # content is a function with argument file. content writes the plot to the device
    content = function(file) {
      if(input$var3 == "png")
        png(file) # open the png device
      else
        pdf(file) # open the pdf device
      # plot(x=x(), y=y(), main = "iris dataset plot", xlab = xl(), ylab = yl()) # draw the plot
      print(ggplot(iris, aes(x=x(), y=y())) + geom_point(shape=1)) # for GGPLOT
      dev.off()  # turn the device off
    
    } 
)
  
  
  
}))

ui.r

library(shiny)
shinyUI(fluidPage(
  titlePanel("Download base plot in Shiny - an example"),
  sidebarLayout(
   sidebarPanel(
      selectInput(inputId = "var1", label = "Select the X variable", choices = c("Sepal.Length" = 1, "Sepal.Width" = 2, "Petal.Length" = 3, "Petal.Width" = 4)),
      selectInput(inputId = "var2", label = "Select the Y variable", choices = c("Sepal.Length" = 1, "Sepal.Width" = 2, "Petal.Length" = 3, "Petal.Width" = 4), selected = 2),
      radioButtons(inputId = "var3", label = "Select the file type", choices = list("png", "pdf"))
),
    mainPanel(
      plotOutput("plot"),
      downloadButton(outputId = "down", label = "Download the plot")
      )
    )
  
  ))

Neat! Thank you for sharing te code for your download button.
In my case, I would like to specify the width and height using a variable I made elsewhere. The variable name is called plotWidth and plotHeight. I have tried:

pdf(file, width = plotWidth, height = plotHeight) but that did not work (although using pdf(file, width = 10, height = 5) works fine). Any suggestions?

The code I use to output the plot to the UI is:
output$facetedPlots <- renderPlot({ if (is.null(v$facetedPlots)) return() v$facetedPlots }, height = plotHeight, width = plotWidth )

And the currently working code for the download button is:
output$downPDF <- downloadHandler( filename = function() { paste("FACS Plot.pdf") }, # content is a function with argument file. content writes the plot to the device content = function(file) { pdf(file) # open the pdf device print(v$facetedPlots) # for GGPLOT dev.off() # turn the device off } )