滑块输入延迟

2023年8月3日 209次阅读

有没有办法让
sliderInput在更改相应的输入$变量之前等待几秒钟？我有一个控制图表的栏,需要在价值变化时重新渲染.我知道使用提交按钮的解决方法,我希望避免需要它. 最佳答案 您可以使用invalidateLater.它可以以一种天真但简洁的方式完成：

library(shiny)
shinyApp(
  server = function(input, output, session) {
      values <- reactiveValues(mean=0)

      observe({
        invalidateLater(3000, session)
        isolate(values$mean <- input$mean)
      })

      output$plot <- renderPlot({
          x <- rnorm(n=1000, mean=values$mean, sd=1)
          plot(density(x))
      })
  },
  ui = fluidPage(
    sliderInput("mean", "Mean:", min = -5, max = 5, value = 0, step= 0.1),
    plotOutput("plot")
  )
)

此方法的问题在于,在更改滑块输入时会触发执行,并且会触发invalidate事件.如果这就是问题,那么您可以尝试更复杂的方法来检查值是否已更改以及已查看的时间值.

library(shiny)
library(logging)
basicConfig()

shinyApp(
  server = function(input, output, session) {
      n <- 2 # How many times you have to see the value to change
      interval <- 3000 # Set interval, make it large so we can see what is going on

      # We need reactive only for current but it is easier to keep
      # all values in one place
      values <- reactiveValues(current=0, pending=0, times=0)

      observe({
        # Invalidate 
        invalidateLater(interval, session)

        # Isolate so we don't trigger execution
        # by changing reactive values
        isolate({
            m <- input$mean

            # Slider value is pending and not current
            if(m == values$pending && values$current != values$pending) {
                # Increment counter
                values$times <- values$times + 1
                loginfo(paste(values$pending, "has been seen", values$times, "times"))

                # We've seen value enough number of times to plot
                if(values$times == n) {
                    loginfo(paste(values$pending, "has been seen", n, "times. Replacing current"))
                    values$current <- values$pending
                }

            } else if(m != values$pending) { # We got new pending
                values$pending <- m
                values$times <- 0
                loginfo(paste("New pending", values$pending))
            }
        })
      })

      output$plot <- renderPlot({
          x <- rnorm(n=1000, mean=values$current, sd=1)
          plot(density(x))
      })
  },
  ui = fluidPage(
    sliderInput("mean", "Mean:", min = -5, max = 5, value = 0, step= 0.1),
    plotOutput("plot")
  )
)
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