Use Progressr in Shiny Apps: Plug-in Backward-Compatible Replacement for shiny::withProgress()

A plug-in, backward-compatible replacement for shiny::withProgress().

withProgressShiny(
  expr,
  ...,
  message = NULL,
  detail = NULL,
  inputs = list(message = NULL, detail = "message"),
  env = parent.frame(),
  quoted = FALSE,
  handlers = c(shiny = handler_shiny, progressr::handlers(default = NULL))
)

Arguments

expr, ..., env, quoted: Arguments passed to shiny::withProgress() as is.
message, detail: (character string) The message and the detail message to be passed to shiny::withProgress().
inputs: (named list) Specifies from what sources the Shiny progress elements 'message' and 'detail' should be updated. Valid sources are "message", "sticky_message" and "non_sticky_message", where "message" is short for c("non_sticky_message", "sticky_message"). For example, inputs = list(message = "sticky_message", detail = "message") will update the Shiny 'message' component from sticky messages only, whereas the 'detail' component is updated using any message.
handlers: Zero or more progression handlers used to report on progress.

Value

The value of shiny::withProgress.

Requirements

This function requires the shiny package and will use the handler_shiny() progressr handler internally to report on updates.

Examples

library(shiny)
library(progressr)

app <- shinyApp(
  ui = fluidPage(
    plotOutput("plot")
  ),

  server = function(input, output) {
    output$plot <- renderPlot({
      X <- 1:15
      withProgressShiny(message = "Calculation in progress",
                        detail = "Starting ...",
                        value = 0, {
        p <- progressor(along = X)
        y <- lapply(X, FUN=function(x) {
          Sys.sleep(0.25)
          p(sprintf("x=%d", x))
        })
      })
      
      plot(cars)

      ## Terminate the Shiny app
      Sys.sleep(1.0)
      stopApp(returnValue = invisible())
    })
  }
)

local({
  oopts <- options(device.ask.default = FALSE)
  on.exit(options(oopts))
  if (interactive()) print(app)
})