R Shiny stability testing

server.R

require(shiny)

# inbuilt dataset
diamonds = ggplot2::diamonds[,c(1,5,7)]

# csv datasets to input via front-end
for(i in 1:3){
    dat <- diamonds[sample(1:nrow(diamonds), 200),]
    write.table(dat, paste0('dat',i,'.csv'), sep=',',row.names=F, col.names=T)
}
diamonds = diamonds[sample(1:nrow(diamonds),200),]

# global variables
inbuilt = FALSE   # whether currently using inbuilt data or not
datapath = ''     # to chech current against previous to see if new dataset input

# secondary plot functions
emptyplot <- function() plot(0, xlim=c(0,100), ylim=c(0,100), col=NA, axes=FALSE, xlab=NA, ylab=NA)

welcome <- function(){
    emptyplot()
    text(10,80,"Please input CSV file data with 3 numerical columns", cex=2, pos=4)
    text(10,65,"Use the inbuilt dataset and the csv files in the app folder..", cex=1.5, pos=4)
    text(10,50,"check app's reliability and how often commands fail", cex=1.5, pos=4)
    text(10,35,"output to PDF", cex=1.5, pos=4)
    text(10,20,"how stable is the app for you?", cex=1.5, pos=4)
}

shinyServer(function(input, output, session) {
  
  # REACTIVE FUNCTION
  plotInput = reactive({

    # import data from inbuilt (internal) or a user-input CSV
    # first must check if reactive is triggered by new data or not:
    newdata = FALSE               # initialise variables
    pagereset = FALSE

    if(input$inbuilt != inbuilt){ # inbuilt data option toggled
        if(input$inbuilt) {       # inbuilt selected
            inbuilt <<- TRUE      # update global
            d <<- diamonds
            newdata = TRUE
        } else{                   # inbuilt de-selected. 
            inbuilt <<- FALSE     # update global
            d <<- NULL            # return splashscreen
            pagereset = TRUE    # would now crash so refresh app instead
        }
    } else {                      # input doesn't relate to inbuilt dataset
        if(!input$inbuilt){       # inbuilt unselected
            if(is.null(input$file1)) { # if null no input received yet
                d = NULL          # so reactive will return splash-screen
            } else {              # data has been input before
                if(input$file1$datapath != datapath){  # new dataset just received
                    datapath <<- input$file1$datapath  # update global
                    d <<- read.csv(datapath, header=TRUE, sep = ',') # update global
                    newdata = TRUE
                    #Sys.sleep(2) # allow file-upload aanimation to finish
                    # reset file handler in page
                    session$sendCustomMessage(type = "resetFileInputHandler", "file1")
                } else NULL    # new input not dataset-related
            }
        }
    }

    # reset/null javascript command - to reset app after inbuilt
    # dataset is de-selected, as the script crashes otherwise..
    reset_js = ifelse(pagereset, "window.location.reload()", '')
    reset_js = paste("<script>", reset_js,";</script>")
    if(pagereset) {
        plot(0, xlim=c(0,100), ylim=c(0,100), col=NA, axes=FALSE, xlab=NA, ylab=NA)
        return(reset_js) # reset instruction
    }

    # no data input so return splash-screen
    if(is.null(d)) {
        welcome()
        return(reset_js)
    }

    # NORMAL PLOT
    
    # # stroke around polygons
    if(input$border != 'none') border = input$border else border = NA

    # PDF handling (save file locally to be passed forward)
    if(input$returnpdf){
        pdf("plot.pdf", width=as.numeric(input$w), height=as.numeric(input$h))
        symbols(d[[1]], d[[2]], circles=sqrt(d[[3]]), inches=as.numeric(input$inches), 
            bg='#ff000020', fg=border)
        dev.off()
    }

    # run plot
    symbols(d$carat, d$depth, circles=sqrt(d$price), inches=as.numeric(input$inches),
            bg='#ff000020', fg=border)
    return(reset_js)
  }) # end reactive

    # OUTPUT ELEMENTS
    
    # PDF file
    output$pdflink = downloadHandler(
      filename = "shiny_plot.pdf", # default browser save filename
      content = function(file) file.copy("plot.pdf", file) # call pre-saved pdf
    )

    # plot
    output$plot = renderPlot({ plotInput() })

    # reset instruction
    output$reset = renderText({ plotInput() })
})

ui.R

require(shiny)

fluidPage(
  titlePanel("Stability testing"),
  sidebarLayout(
    sidebarPanel(

      # this css just resets the CSV upload function
      tags$head(
        tags$style(type="text/css", ".shiny-bound-input { width: 40px; }"),
        tags$script('
          Shiny.addCustomMessageHandler("resetFileInputHandler", function(x) {      
          var id = "#" + x + "_progress";
          var idBar = id + " .bar";
          $(id).css("visibility", "hidden");
          $(idBar).css("width", "0%");
          });
        ')
      ),

      # inputs
      h4('Input options'),
      p("Chose inbuilt dataset or upload a CSV:"),
      checkboxInput('inbuilt', 'Inbuilt dataset (app resets when de-selected)', FALSE),
      fileInput('file1', '', accept = 'text/comma-separated-values'),

      # plot layout
      h4('Plot options'),
      selectInput(inputId="border", label="Outline colour:", choices=list(black='black', white='white', none='none'), width=150, selected='black'),
      br(),
      sliderInput(inputId="inches", label = "Circle size (higher values can crash the app)", min=0.05, max=.5, value=.2, width=150),

      # PDF output
      br(),
      h4('PDF output'),
      p("Buggy: plot disappears, but link still downloads last plot. Sometimes after download app crashes"),
      checkboxInput('returnpdf', 'Save plot to PDF?', FALSE),
      strong("PDF size (inches):"),
      textInput(inputId = "w", label = "width: ", value = "12"),
      textInput(inputId = "h", label = "height: ", value = "9"),
      br(),
      downloadButton('pdflink', label = "Download")
    ),

    mainPanel(
      htmlOutput('reset'), # reset command (when inbuild dataset de-selected)
      imageOutput('plot')
    )
  )
)