R shiny: reset plot to default state

Question

This is a follow up to my question here.

I have a plot that is displayed when I start the shiny app, then I want to run some code which \"animates\" some sampling fr

Answer 1

As per my comment in your previous question I have done the changes by adding plot1<<-NULL inside the observeEvent and then again render the original plot.

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

    plot1 <- NULL
    count <- 0

    output$plot1 <- renderPlot({
      plot1 <<- ggplot(data, aes(x=x, y=y)) + geom_point(colour="red") + theme_bw()
      plot1 <<- plot1 + geom_vline(xintercept = mean(data$x), size=1.1, colour="red")
      plot1
    })

    observeEvent(input$button,{
      plot1 <<- NULL

      output$plot1 <- renderPlot({
        plot1 <<- ggplot(data, aes(x=x, y=y)) + geom_point(colour="red") + theme_bw()
        plot1 <<- plot1 + geom_vline(xintercept = mean(data$x), size=1.1, colour="red")
        plot1
      })

      count <<- 0
      output$plot1 <- renderPlot({

        count <<- count+1
        invalidateLater(500, session,  count < input$surveys)
        data$sampled <- "red"
        sample.rows <- sample(data$ID, input$n)
        data$sampled[sample.rows] <- "green"

        plot1 <<- plot1 + geom_point(x=data$x, y=data$y, colour=data$sampled, size=2)

        sample.mean.x <- mean(data$x[sample.rows])

        plot1 <<- plot1 + geom_vline(xintercept = sample.mean.x, colour="green")

        plot1

      })
    })
  }

In the above case you do not need the reset button. In case if you want a reset button you can put the plot<<-NULL and renderPlot inside the observeEvent of the reset button. Something like this:

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

    plot1 <- NULL
    count <- 0

    output$plot1 <- renderPlot({
      plot1 <<- ggplot(data, aes(x=x, y=y)) + geom_point(colour="red") + theme_bw()
      plot1 <<- plot1 + geom_vline(xintercept = mean(data$x), size=1.1, colour="red")
      plot1
    })

    observeEvent(input$button,{

      count <<- 0
      output$plot1 <- renderPlot({

        count <<- count+1
        invalidateLater(500, session,  count < input$surveys)
        data$sampled <- "red"
        sample.rows <- sample(data$ID, input$n)
        data$sampled[sample.rows] <- "green"

        plot1 <<- plot1 + geom_point(x=data$x, y=data$y, colour=data$sampled, size=2)

        sample.mean.x <- mean(data$x[sample.rows])

        plot1 <<- plot1 + geom_vline(xintercept = sample.mean.x, colour="green")

        plot1

      })
    })


    observeEvent(input$reset,{

      plot1<<- NULL


      output$plot1 <- renderPlot({
        plot1 <<- ggplot(data, aes(x=x, y=y)) + geom_point(colour="red") + theme_bw()
        plot1 <<- plot1 + geom_vline(xintercept = mean(data$x), size=1.1, colour="red")
        plot1
      })


    })

  }

Hope this helps!