Question

我想知道如何显示经过多次修改的变量的值，我尝试使用future方法，但它不起作用。

library(shiny)

# library(ipc)
# library(future)
# library(promises)
# plan(multiprocess)

ui <- fluidPage(
  textOutput("t")
)

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

  status <- reactiveVal({NULL})
  observe({
      status("beginning")
      # a function that takes a lot of time
      Sys.sleep(2)
      status("End")
  })

  # observe({
  #   future({
  #     queue$producer$fireAssignReactive("var", 0)
  #     Sys.sleep(2)
  #     queue$producer$fireAssignReactive("var", 1)
  #   }); NULL
  # })

  output$t <- renderText(status())
}

shinyApp(ui, server)

Answer 1

此代码每两秒将“ var”增加1。这就是你想要的吗？

library(shiny)

# library(ipc)
# library(future)
# library(promises)
# plan(multiprocess)

ui <- fluidPage(
  textOutput("t")
)

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


  var <- reactiveVal(-1)


  # observer that invalidates every second. If timer is active, decrease by one.
  observe({
    invalidateLater(2000, session)
    isolate({
    var(var()+1)
      })
  })
  output$t <- renderText(var())
}

shinyApp(ui, server)

显示多次修改的变量的值

1 个答案: