具有进度条的R Shiny Async [英] R Shiny Async with Progress Bar

问题描述

Shiny中的异步处理应该具有长期运行的功能，并将控制权交还给用户.但是，最好还是让用户知道计算在后台运行.我无法弄清楚如何构造异步进程以在后台运行并仍然显示进度指示器.以下是我一直在尝试的示例代码.我认为进度指示器是一个问题，但是表的创建似乎也无法用于异步处理.

Async processing in Shiny is supposed to take a long-running function and give control back to the user. However, it would still be nice to let the user know that the computation is running in the background. I cannot figure out how to structure the async process to run in the background and still display a progress indicator. Below is the example code I've been fiddling with. I think the progress indicator is one issue, but also the creation of the table doesn't seem to be working with async processing.

library(shiny)
library(future)
library(promises)
plan(multiprocess)

shinyApp(
  ui = basicPage(
    tableOutput('table'),
    actionButton('goTable', 'Go table')
  ),

  server = function(input, output, session) {

    table_data <- reactive({

      # make reactive to button click
      input$goTable

      # Create a Progress object
      progress <- shiny::Progress$new()
      progress$set(message = "Building Table", value = 0)
      # Close the progress when this reactive exits (even if there's an error)
      on.exit(progress$close())

      # build up the table data
      future({
        this_dat <- NULL
        for(i in 1:5){
          Sys.sleep(1)
          this_dat <- rbind(this_dat, data.frame(i=i))
          # increment progress
          progress$inc(1/5)
        }
      })
      return(this_dat)
    })

    output$table <- renderTable({
       table_data()
    })    
  }
)

推荐答案

签出ipc软件包:

## Only run examples in interactive R sessions
if (interactive()) {
library(shiny)
library(future)
plan(multiprocess)
ui <- fluidPage(
  actionButton("run","Run"),
  tableOutput("dataset")
)

server <- function(input, output, session) {

  dat <- reactiveVal()
  observeEvent(input$run, {
    progress <- AsyncProgress$new(session, min=1, max=15)
    future({
      for (i in 1:15) {
        progress$set(value = i)
        Sys.sleep(0.5)
      }
      progress$close()
      cars
    }) %...>% dat
    NULL
  })

  output$dataset <- renderTable({
    req(dat())
  })
}

shinyApp(ui, server)
}

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