waitress.md

The Waitress

The waitress will let you display loading bars on the entire screen or specific elements only.

How to

Note that the waitress is a reference class.

1. Place use_waitress anywhere in your UI.
2. Set up the waitress in your server with call_waitress or Waitress$new().
3. Programatically call the set, inc, and auto methods.
4. Don't forget to programatically hide the loading screen with the close method.

See ?waitress for the documentation.

Make sure you include the dependencies with useWaitress.

Plot

The waitress can be applied to a specific element or the whole page. Note that call_waitress and Waitress$new() takes a CSS selector, so if you want to apply it to a plot use #plotId.

library(shiny)
library(waiter)

ui <- fluidPage(
  useWaitress(),
  plotOutput("plot", width = 400)
)

server <- function(input, output){
  
  waitress <- Waitress$new("#plot") # call the waitress
  
  output$plot <- renderPlot({
    
    for(i in 1:10){
      waitress$inc(10) # increase by 10%
      Sys.sleep(.3)
    }
    
    hist(runif(20))
    waitress$close() # hide when done
	})

}

shinyApp(ui, server)

Selector

Because the waitress takes a selector, we can apply it to different parts of the page, using a class or any other selector, like the nav. Note that you can set the range of the progress bar when you initialise it, you are not limited to percentages.

library(shiny)
library(waiter)

ui <- navbarPage(
  "Waitress on nav",
  tabPanel(
    "home",
    useWaitress(),
    plotOutput("plot")
  )
)

server <- function(input, output){
  
  # now waitress ranges from 0 to 100
  waitress <- Waitress$new("nav", theme = "overlay", min = 0, max = 10)
  
  output$plot <- renderPlot({
    
    for(i in 1:10){
      waitress$inc(1) # increase by 10%
      Sys.sleep(.5)
    }
    
    hist(runif(100))
    waitress$close() # hide when done
  })

}

shinyApp(ui, server)

Page

If you do not specify a selector to call_waitress then it is applied to the whole page. Note that you can change the color of the waitress in use_waitress.

library(shiny)
library(waiter)

ui <- fluidPage(
  useWaitress(color = "#7F7FFF"),
  h2("waitress on entire page"),
  actionButton("load", "load")
)

server <- function(input, output){
  
  waitress <- Waitress$new(theme = "overlay-percent") # call the waitress
  
  observeEvent(input$load, {
    waitress$
      auto(percent = 5, ms = 150) # increase by 5 % every 150 ms
      Sys.sleep(3.5)
      waitress$close()
	})

}

shinyApp(ui, server)

Infinite

An infinite loading bar is useful when you cannot compute increments.

library(shiny)
library(waiter)

ui <- fluidPage(
  useWaitress(),
  actionButton("btn", "render"),
  plotOutput("plot", width = 400)
)

server <- function(input, output){
  
  waitress <- Waitress$new("#btn", theme = "overlay", infinite = TRUE)
  
  output$plot <- renderPlot({
    input$btn

    waitress$start()
    
    Sys.sleep(3)
    
    hist(runif(100))
    waitress$close() # hide when done
  })

}

shinyApp(ui, server)

Notifications

You can also use the waitress to display notifications.

library(shiny)
library(waiter)

ui <- fluidPage(
  useWaitress(),
  actionButton("btn", "render"),
  plotOutput("plot", height = "90vh")
)

server <- function(input, output){
  
  waitress <- Waitress$new(theme = "overlay-percent", min = 0, max = 10)
  
  output$plot <- renderPlot({
    input$btn

    # use notification
    waitress$notify()
    
    for(i in 1:10){
      waitress$inc(1) # increase by 10%
      Sys.sleep(.3)
    }
    
    hist(runif(100))
    waitress$close() # hide when done
  })

}

shinyApp(ui, server)

Message

You can also layer a message on the waitress.

library(shiny)
library(waiter)

ui <- fluidPage(
  useWaitress(),
  plotOutput("plot")
)

server <- function(input, output){
  
  waitress <- Waitress$new("#plot") # call the waitress
  
  output$plot <- renderPlot({
    waitress$start(h3("Loading Stuff..."))
    
    for(i in 1:10){
      waitress$inc(10) # increase by 10%
      Sys.sleep(.3)
    }
    
    plot(runif(100))
    waitress$close() # hide when done
  })

}

shinyApp(ui, server)

On render

Like the waiter, the waitress can be hidden when the element (plot, table, etc.) which it covers is rendered.

library(shiny)
library(waiter)

ui <- fluidPage(
  useWaitress(),
  actionButton("btn", "Render"),
  plotOutput("plot", width = 400)
)

server <- function(input, output){
  
  waitress <- Waitress$new("#plot", hide_on_render = TRUE) # call the waitress
  
  output$plot <- renderPlot({
    input$btn

    waitress$start()
    
    for(i in 1:10){
      waitress$inc(10) # increase by 10%
      Sys.sleep(.3)
    }
    
    plot(runif(100))
	})

}

shinyApp(ui, server)

httr

Use instead of httr::progress, replace it with httr_progress.

library(httr)
library(shiny)
library(waiter)

cap_speed <- config(max_recv_speed_large = 10000)

ui <- fluidPage(
  useWaitress(),
  actionButton(
    "dl",
    "Download"
  ),
  plotOutput("plot")
)

server <- function(input, output){
  w <- Waitress$new("#plot")

  dataset <- eventReactive(input$dl, {
    x <- GET(
      "http://httpbin.org/bytes/102400", 
      httr_progress(w), 
      cap_speed
    )

    runif(100)
  })

  output$plot <- renderPlot(plot(dataset()))
}

shinyApp(ui, server)

Progress

You can use withProgressWaitress, setProgressWaitress, and incProgressWairess, they are used in a similar fashion as withProgress, setProgress, and incProgress from shiny.

library(shiny)
library(waiter)

ui <- fluidPage(
  useWaitress(),
  br(),
  actionButton(
    "load",
    "Load stuff"
  )
)

server <- function(input, output) {
  observeEvent(input$load, {
    withProgressWaitress({
      for (i in 1:15) {
        incProgressWaitress(1)
        Sys.sleep(0.25)
      }
    }, selector = "#load", max = 15, theme = "overlay-percent")
  })
}

shinyApp(ui, server)