r - Is there a way to display plots as they build in Shiny instead of waiting for all of them? -

i have shiny dashboard many plots, of take multiple seconds build. once last 1 builds, display. instead each plot display completes. understand r single-threaded, seems though there must way "return execution display code" or that.

this code demonstrates issue:

library(shiny)  ui <- fluidpage(   title = "page loading test"   , h1("page loading test")   , plotoutput("plot1")   , plotoutput("plot2")   , plotoutput("plot3")   , plotoutput("plot4") )  server <- function(input, output) {    output$plot1 <- renderplot({      sys.sleep(10)      plot(rnorm(50))    })     output$plot2 <- renderplot({      sys.sleep(10)      plot(rnorm(50))    })     output$plot3 <- renderplot({      sys.sleep(10)      plot(rnorm(50))    })     output$plot4 <- renderplot({      sys.sleep(10)      plot(rnorm(50))    }) }  shinyapp(ui = ui, server = server) 

the sleeps merely emulate slow execution.

it takes 40s page display. page take 10s display plot1, additional 10s display plot2, etc. there call updatepage() can called @ bottom of each plot function?

on page, have loading animations running user aware activity occurring, makes more obvious when load @ once.

i could, of course, have simpler page, wouldn't dashboard. :)

you can use reactivetimer() refresh page regularly.

and can save plots in list of plots print them @ each refresh.

i had reorder renderplot functions step iterator renders 1 plot @ time

also chose not start first render right away plot "loading" plots.

library(shiny)  ui <- fluidpage(    title = "page loading test"   , h1("page loading test")   , plotoutput("plot1")   , plotoutput("plot2")   , plotoutput("plot3")   , plotoutput("plot4") )  # loading plot plot(-1:1, -1:1, type = "n", xlab = "", ylab = "") text(0,0, "loading",cex = 5) loading <- recordplot()  plotlist <- vector("list",4)  step <- 0 # plot should rendered next  server <- function(input, output, session) {   autoinvalidate <- reactivetimer(10, session)   output$plot4 <- renderplot({autoinvalidate();     if(step>4){plotlist[[4]]}     else if(step==4){step <<- step+1     print("rendering step 4")     sys.sleep(10)     plotlist[[4]] <<- {plot(rnorm(50));recordplot()}} else loading   })   output$plot3 <- renderplot({autoinvalidate();     if(step>3){plotlist[[3]]}     else if(step==3){step <<- step+1     print("rendering step 3")     sys.sleep(10)     plotlist[[3]] <<- {plot(rnorm(50));recordplot()}} else loading   })   output$plot2 <- renderplot({autoinvalidate();     if(step>2){plotlist[[2]]}     else if(step==2){step <<- step+1     print("rendering step 2")     sys.sleep(10)     plotlist[[2]] <<- {plot(rnorm(50));recordplot()}} else loading   })   output$plot1 <- renderplot({autoinvalidate();     if(step>1){plotlist[[1]]}     else if(step==1){step <<- step+1     print("rendering step 1")     sys.sleep(10)     plotlist[[1]] <<- {plot(rnorm(50));recordplot()}} else {step <<-1;loading}   }) } shinyapp(ui = ui, server = server)